The Europaen Commission The Commission on the Protection of the Black Sea Against Pollution
BSC LogoEC Logo

Report Contents

Preface Chapter 1A Chapter 1B Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12
List of Tables List of Figures

State of Environment Report 2001 - 2006/7

Chief Editor, Prof. Dr. Temel Oguz, Institute of Marine Sciences, Middle East Technical University, Erdemli, Turkey

Chapter 9 - State of Marine Living Resources

State of the Environment of the Black Sea - 2009

CHAPTER 9 THE STATE OF MARINE LIVING RESOURCES (V. Shlyakhov & G. Daskalov)

V. A. Shlyakhov

YugNIRO, Kerch, Crimea, Ukraine

G. M. Daskalov

CEFAS Lowestoft laboratory, Lowestoft, Suffolk, UK

9.1. Introduction

In the context of this chapter, ?Marine living resources? (hereinafter it is referred to as MLR) comprise the populations (exploited, being exploited or being able to be exploited by humans) of finfishes (hereinafter ? fishes), mollusks, crustaceans, water plants and other living organisms inhabiting the Black Sea, excluding waterfowl and mammals. About 200 fish species, more than 500 mollusks species and water plants?macrophytes (red and brown algae as well as marine floral plants) inhabit the Black Sea. Among the whole specific diversity, the greatest economic value, however, is not more than two dozens of species that produce about 98% of catch in 1996 ? 2005 (Fig. 9.1). The rest 2% included commercially less important fishes, mollusks, crustaceans and other aquatic organisms. The main portion of catches falls into three groups ? anadromous, pelagic, and demersal fishes. In each of these groups, more than 90% of capture volume fall on several leading species. As a whole, the total mean annual catch of MLR in 1996 ? 2005 was at the level of 410 thousand tons varying annually between 330 thousand tons and 500 thousand tons, that is more than 30 thousand tons higher than the mean catch in 1989 ? 1995 (Fig. 9.2).

This chapter summarizes the state of marine living resources in the Black Sea during the last 10 years with respect to the previous decades. In particular, the state of MLR will be assessed for 1996 ? 2005 as compared with the earlier period to explain the changes occurred. The chapter was benefited from the data used for the TDA (Technical Task Team National Experts on Fisheries) Reports (2006), kindly submitted to the BSERP - PIU by the authors. Information on MLR catches of the Black Sea countries in 1989 ? 2005 was taken from the FAO statistical data base with some corrections made on the basis of TDA reports (2006) and the Black Sea Commission Information System data base.

9.2. The state of key anadromous fishes

The anadromous species of the Black Sea include the pontic shad (Alosa pontica) and three sturgeon species Acipenser gueldenstaedtii, Acipenser stellatus, Huso huso. Among fishes by the capture volume, anadromous fishes take the last place (Fig. 9.1), but their high consuming and economical value determines their specific role in the structure of the MLR. Their life cycle consists of marine period (wintering and fattening) and river period (spawning and migration of newly born juveniles into the sea). Stocks of anadromous fishes are formed mainly by the Danube populations. The catch data of anadromous fishes (Fig. 9.3) suggest decline of their commercial value in 1996 ? 2005 as compared with the previous period. Following the minimal catch occurred in 1999, nevertheless an increasing trend of annual catches was observed due particularly to the recovery of Pontic shad.

?

Fig. 9.1. Commercial exploitation of Marine Living Resources in the Black Sea in 1996 ? 2005.

Fig. 9.2. Total capture production of Marine Living Resources in the Black Sea in 1989 ? 2005.

9.2.1. Sturgeons

Out of six sturgeon species of family Acipenseridae inhabited the Black Sea and inflowing rivers, three species called the Russian sturgeon (A. gueldenstaedtii), starred sturgeon (A. stellatus) and beluga (Huso huso) are most common. They are large-sized fishes with long life cycle: beluga lives up to 100 years and reaches the weight more than 1 ton with length of 490 cm; for Russian sturgeon maximum recorded age is 37 years, the length is 236 cm and weight is 115 kg; starred sturgeon reaches the length of 218 cm, weight 54 kg and age 23 years old (Pirogovskiĭ et al., 1989; Popova et al., 1989; Vlasenko et al., 1989). Russian sturgeon and starred sturgeon feed mainly on benthic organisms, namely mollusks and Polychaetae. Beluga is a typical predator, feeding on fish exclusively. Anadromous sturgeons make extended migrations during their life from the sea into the rivers; larvae drift after hatching and juveniles in rivers; and back into the sea after completion of spawning.

Fig. 9.3. Total capture production of main anadromous fishes in the Black Sea during ?1989 ? 2005.

The main fattening and wintering grounds of the Danube and Dnieper populations of the Russian sturgeon and starred sturgeon as well as juveniles of beluga are the coastal waters of Ukraine. The Danube, the Dnieper and the Rioni Rivers offer most important habitats for their reproduction. Major part of the adult sturgeon populations in the sea comes from the Danube and Dnieper populations.? The Danube populations of Russian sturgeon, starred sturgeon and beluga are all abundant. Among Dnieper populations, the Russian sturgeon is the most abundant, artificial reproduction (restocking) play an important role for keeping its abundance above a certain level.? In Ukraine, restocking of sturgeons and releasing their fingerling into the wild is carried out in the Dnieper Sturgeons? Rearing Plant. From 1985 till 1995 this farm has released into the sea 1 ? 2.5 million juveniles per year (generally, Russian sturgeon) (Prodanov et al., 1997; Shlyakhov, 2003). The scale of sturgeons? restocking is the largest in the River Dnieper; however, it has the tendency to decrease up to 0.354 million individuals in 2005 and 0.118 million individuals in 2006 (Table 9.1).

According to the methodology described by Shlyakhov and Akselev (1993) and Shlyakhov (1994) and the results of bottom trawl surveys (1981, 1984, 1987, 1991, 1992, 1993, 1994, 1998, and 2002) that were undertaken on the wintering grounds in the Karkinitsky Bay in February-March, the Russian sturgeons? abundance acquired a continuous growth in 1981 ? 1993, but started decreasing in subsequent years (Fig. 9.4). On the contrary, the abundance of starred sturgeon remained more or less stable around 1.5 millions of individuals until 1994 and reduced gradually afterwards to less than 0.5 millions of individuals at the end of the 1990s and the early 2000s. The abundance of beluga juveniles decreased from 0.4 to around 0.1 million individuals, and then remained steady around 0.1 ? 0.15 million individuals up to 2002 that was about one third of the level in 1981. Thus, the total sturgeon abundance increased from 0.2 millions of individuals in 1966 ? 1974 (Ambroz, Kirilluk, 1979) to 5.3 ? 6.2 millions of individuals in 1992-93. This increase was due to population growth of Russian sturgeon under highly efficient protection measures and restocking. Starting by 1994, their total abundance however decreased gradually up to 2 millions individuals in 1998 and 1.5 millions of individuals in 2002.

Table 9.1. The total and individual populations of the Russian and Starred sturgeon and Beluga in the Rivers Dnieper and Danube in 1996 ? 2006, in million individuals per year. Data sources: for RO ? R. Reinartz (2002), for BG and UA ? BSIS (2007).

Year Country River Russian sturgeon Starred sturgeon Beluga Total

1996

RO

Danube

0.010

-

-

0.010

UA

Dnieper

?

?

-

4.018

1998

BG

Danube

0.001

-

?

0.001

1999

BG

Danube

0.027

-

0.003

0.030

2000

BG

Danube

0.020

-

0.001

0.021

RO

Danube

-

0.068

-

0.068

2001

BG

Danube

0.028

-

-

0.028

UA

Dnieper

2.370

-

-

2.370

2002

BG

Danube

0.022

-

-

0.022

UA

Dnieper

2.366

0.142

-

2.508

2003

BG

Danube

0.161

-

0.005

0.161

2004

BG

Danube

0.127

-

-

0.127

UA

Dnieper

1.071

-

-

1.071

2005

UA

Dnieper

0.354

-

-

0.354

2006

UA

Dnieper

0.112

0.006

-

0.118

The rejuvenation of sturgeon schools after 2000 was reflected in their smaller length-weight characteristics in the Ukrainian sector of the Danube. 82% of all analyzed fish samples corresponded to the range of 96 ? 105 cm and 4.96 kg in weight. The male:female ratio for both starred and Russian sturgeon schools was 82%:18%. At present starred sturgeon population corresponding to 60% of the total population at 7 years of age made the basis of sturgeons? catches in the Danube delta; other age groups as well as Russian sturgeon are found in smaller amounts in catches (Table 9.2).

The changes in Russian and starred sturgeon abundances in the Danube school (Fig. 9.4) imply larger amount of fishing of Russian sturgeon than starred sturgeon after 1993 ? 1994 that made the starred sturgeon progressively more predominant species forming almost 75% of the total population.

The fact that all acipenseriform species were included in the Convention of International Trade of Endangered Species (CITES Appendix II /Notification to the Parties No. 1998/13 Conservation of Sturgeons) since 1998 evidences an unfavorable state of sturgeon populations during the present decade although the data shown in Fig. 9.4 did not extend beyond 2002. In the opinion of the IUCN experts, stocks of migratory sturgeons in the Lower Danube River have been overexploited and a collapse of stocks was inevitable with the same rate of exploitation.

Fig. 9.4. The total abundance (in million of individuals) of three anadromous sturgeon species in the north-western Black Sea according to the data of YugNIRO trawl surveys and mathematical modeling (taken from Shlyakhov, 2003). Red bars: Russian sturgeon; blue bars: Starred sturgeon; yellow line: Beluga.

Table 9.2. Length-weight and age characteristics of mature Russian and starred sturgeons in the Ukrainian Danube in 2003

Age 6 7 8 9 10 11 12 13 14 15

Starred sturgeon

L (cm)

101.0

100.8

102.8

104.5

110.5

-

-

-

103.0

-

Weight(kg)

4.6

5.42

5.66

6.25

7.50

-

-

-

5.0

-

%

10.0

60.0

22.0

4.0

3.0

-

-

-

1.0

-

Russian sturgeon

L (cm)

-

-

110.0

112.7

113.5

114.8

115.9

116.5

117.0

126.0

Weight(kg)

-

-

8.50

9.93

10.43

10.68

11.57

14.00

14.00

16.50

%

-

-

4.0

12.0

16.0

20.0

28.0

8.0

4.0

8.0

Statistics on targeted and non-targeted fisheries comprise only officially documented catch or by-catch. ?Unreported? catch due to its hidden part during legal fisheries and from poachers? catch as well as dead fish which is not landed by some reasons (fish died in nets, discarded illegal catch, etc.) were not usually included in statistics, but their proportion may be much higher than the officially reported catch size. Therefore, any reliable assessment for the state of sturgeons need to include the contribution of unreported catch as published earlier by Prodanov et al. (1997); Navodaru et al. (1999); Shlyakhov et al. (2005).

Immediately after the USSR disintegration, the unreported catches increased up to 280 tons (in 1994) due to the illegal fishing of sturgeons? wintering aggregations in the Karkinitsky Bay (Zolotarev et al., 1996). 60 ? 70% of these poaching catches consisted of Russian sturgeon. The unreported catch of anadromous sturgeons was estimated as ~600 tons for 1995 that was 12 times more than the officially reported catch by all the Black Sea countries. This number is expected to be even higher since the calculations did not cover all areas of the sturgeons? fishery and no correction was made for fish death at sea. In the Sea of Azov, mean annual unreported catch of the Russian sturgeon was estimated as 2.0 ? 4.8 thousand tons for 1988 ? 1997 (Table 9.3). As depicted in Table 9.3, overfishing led to the collapse of the Azov Sea sturgeon stock and its fisheries within less than 10 years. It can?t be overcome till now in spite of the complete banning of commercial fisheries of Azov sturgeons after 2000 by the Russian Federation and Ukrainian authorities.

Table 9.3. Mean annual and unreported catches and total abundance of Russian sturgeon according to the data of trawl surveys in 1988 ? 2005 in the Sea of Azov (assessments of unreported catch were taken from Shlyakhov et al., 2005).

Years

Total abundance

(thousand individuals)

Catch, tons

Official

Unreported

1988-90

12606

772*

4814

1992-94

8264

1143*

3213

1995-97

4357

427

2040

1998-00

2785

156

984

2001-03

1757

6

109

2004-05

745

1

54

* - Russian sturgeon and starred sturgeon

According to the official statistics, the total catch of all three species of anadromous sturgeons in the Black Sea basin increased from 19 tons in 1994 to 211 tons in 2003 and then sharply declined to 42 ? 43 tons in 2004 ? 2005. This abrupt decline may be interpreted as an evidence of the stock collapse due to the recruitment failure.

Besides over-exploitation during the last 10 years, anadromous sturgeon populations were also adversely affected by habitat loss and habitat degradation as a consequence of? loss of shelters, feeding and reproduction habitats; alteration of the hydrological regime of surface and ground waters (loss of regular soil aeration and moistening), changes in the sediment regime (balance of erosion and sedimentation processes), loss of typical and rare habitats and species diversity especially in flood plains, reduced flood retention capacity resulting in increased flood hazards downstream of? dams, reduced self-purification capacity resulting in increased need for expensive water purification, reduced productivity (regular free nutrient input) for forestry, agriculture and fisheries, reduction of recreational value.

In accordance with the assessments of national experts, the three main threats for anadromous fishes are as follows.

Illegal fishing and use of destructive harvest techniques: Illegal fishing since 1993 was the major reason of overfishing of sturgeons, and perhaps the collapse of their stocks. Control of poaching in the former Soviet Union countries had no effect at all; responsible authorities were often engaged in illegal fishery (Toje and Knudsen, 2006).? In the opinion of IUCN experts, control of poaching and illegal caviar trade should be carried out via development and implementation of regional trade and law enforcement agreements; improvement of social and economic conditions of people; improvement enforcement of existing laws.

Loss of valuable spawning and nursery habitats in rivers and lagoons: Recovery of spawning and nursery habitat in rivers and lagoons in the nearest future is not realistic. Key habitats in the Danube, Dnieper, Rioni Rivers and in the Black Sea from catches or by-catches should be protected.

Modification in river flow regimes (including building of dams and drain of meadow): Reduction and loss of anadromous sturgeons may also be connected with dam constructions.? Prior to the dam construction, the Dnepr sturgeons were used to travel up to Mogilev (Belarus) and the major spawning area was extended from Kherson all over the lower Dnepr, including the Dnepr rapids. After construction of Kakhovka dam in 1956, the spawning area reduced to 75 km. Even in the vicinity of New Kakhovka and village Lvovo, conditions for spawning of sturgeons became unsuitable. Similarly, important spawning sites in the Middle Danube River were reduced after the construction of the Iron Gate Dam I in 1972. The Iron Gate Dam II in 1980 further reduced the migration potential of sturgeons. The dams in the Turkish Rivers Sakarya, Yesilirmak and Kizilirmak were the reason of complete loss of their significance for spawning of anadromous sturgeons.

Banning of commercial sturgeon fisheries by Turkey more than 15 years ago, Ukraine since 2000 and Romania since 2006 was an important step towards conservation of sturgeon stocks.? However, such measures as well as insufficiently developed restocking and inefficient control of poaching cannot solve this transboundary problem. Concerted actions of all Black Sea countries are necessary.

9.2.2. Pontic shad

Pontic shad (Alosa pontica) is an anadromous pelagic fish reaching the length of 45 cm, maturing at the age of 3-4 years. It is not found in the catches at the age older than 6-8 years. Mature Pontic shad feeds mainly on fish (anchovy, sprat), and to a lesser extent, crustaceans. It is considered that two populations of Pontic shad ? Don and Danube ones ? inhabit in the Azov and Black Seas. The Don populations winter in the eastern part of the sea from the Crimean coasts to Batumi and the Danube populations in the western part of the sea (Svetovidov, 1964). More recent studies suggested a possibility of wintering along the Turkish coasts (Prodanov et al., 1997). The Danube population migrates into the Danube, Dnieper and Dnestr Rivers for spawning in spring. Its fisheries are conducted both at sea during spring migration period in Bulgaria and Romania and during wintering phase in Turkey and in the western rivers by Bulgaria, Romania and Ukraine. Its fishery is almost absent in the territorial waters of Georgia and Russian Federation.

According to assessments by Ivanov and Beverton (1985) on the basis of analysis of age cohorts in the catches of Bulgaria, Romania and the former USSR for 1963 ? 1979, the Danube population of Pontic shad varied from 17 million individuals in 1968 to 114 million individuals in 1974. The corresponding stock was 3 and 20 thousand tons. In subsequent studies (Prodanov et al., 1997) high abundance of the Pontic shad in 1974 was estimated as 122 million individuals without including the Turkish catches and considering only the catches in the eastern part of the sea which possibly did not include the Danube school.

After the peak in 1974 ? 1975 till the early 1990s, the stock and catches of Pontic shad tended to reduced even excluding the Turkish catch. After 1989, the catch statistics also included the Turkish catches that accounted for 2 ? 4 thousand tons from 1989 to 1995 (Fig. 9.5). Intensification of catch in the Turkish waters was most likely due to the yearning of fishermen to compensate their losses as a result of collapses in anchovy and horse mackerel fisheries. The extensive harvesting then caused sharp drop in shad catches after 1994 to less than 500 tons in 1999 ? 2001. The Turkish catch increased again in 2005, exceeding 1 thousand tons. The catches of Bulgaria, Romania and Ukraine in 1989 ? 1998 were approximately at the same level of 1 thousand tons. It declined sharply in 1999 and acquired a slight recovery afterwards.

The Turkish Pontic shad fishery appears to introduce an important contribution to the sharp decline of the stock after 1995. The Danube population generally winters along both western and eastern coastal waters of Turkey. The Don population of Pontic shad also winters along the eastern Turkish coastal waters.? Younger year classes of these Pontic shad populations were therefore harvested in the Turkish waters during their overwintering phase, as their older age classes were caught along the coasts of Bulgaria, Romania and Ukraine during spawning migrations into the rivers, mainly the Danube. If that was the case, intensification of the Turkish fisheries on the Pontic shad caused depletion of the stock of potential breeders in 1990 ? 1995 that then became an important cause of stock and catch decline after 1995.

Fig. 9.5. Changes in Pontic shad catches in the Black Sea basin in 1989 ? 2005.

The stock assessment of the Danube shad at the level of 4 ? 6 thousand tons during 1989?1992 (Prodanov et al., 1997) might be an underestimation, since the analysis did not include the Turkish catch which in fact exceeded the total catch of Bulgaria, Romania and Ukraine in those years. The other source of underestimation was the correction for poaching in the Danube and adjacent coastal waters. Assessment for the abundance and biomass of the Danube population of shad in 1996 ? 2005 was not available. By analyzing of the composition and values of annual catches of Pontic shad by Odessa YugNIRO Centre, the shad biomass was assessed as ~1000 tons in 1998 ? 2004 except a temporary drop to ~500 tons in 2001in the Ukrainian sector of the Danube (Fig. 9.6). An implication of such rather uniform stock assessment is the importance of including the Turkish catch data into the stock estimation analysis without which it wouldn?t be possible to explain reliably the stock changes of Pontic shad over the basin.

The present state of the Danube population of Pontic shad should be regarded as unfavorable. Even taking into account unfortunate ecological changes due to the environmental factors such as lower water level, water temperature and pollution that could actually affect the success of the Danube shad reproduction, the most important cause of the stock decrease appears to be the overfishing mainly in the Danube Delta area (Radu, 2006). Indeed, poaching fishery for shad in the lower Danube for recent 10 years has become wide-scale, although it has not been assessed properly so far. Perhaps, marine fisheries of Turkey make a comparable contribution to the overexploitation of the Danube stock of shad.

The main threats for anadromous Pontic shad are almost the same as for sturgeons. The only additional point which might be added is the slightly better state of shad stock as compared with sturgeon due to their natural abilities for rapid recovery. Therefore, the regional level of fishery regulation should be sufficient to improve the Danube population of Pontic shad.

Fig. 9.6. Turkish and the sum of Bulgarian, Romanian and Ukranian catch variations of Pontic shad in the Black Sea as well as its biomass estimation in the Ukrainian Danube region.

9.3. The state of key pelagic fishes

Pelagic fishes, particularly their small-sized plankton-eating types are the most abundant in the Black Sea ichthyocenosis. This factor defines their leading role in fisheries. The main target species of fisheries is European anchovy (Engraulis encrasicolus), whose catch has varied from 31% in 1991 to 75% in 1995 of the total MLR harvest during the last 15 years. Mediterranean horse mackerel (Trachurus mediterraneus), European sprat (Sprattus sprattus), Atlantic bonito (Sarda sarda) and bluefish (Pomatomus saltatrix) are the major pelagics in terms of fishing value. The latter of these three species are large-sized predators which enter the Black Sea from the Marmara and Aegean Seas for feeding and spawning in spring and turn back for wintering in late autumn. The catch data suggest partial recovery of major pelagic species after the fishery collapse at 1991 (Fig. 9.7).

Fig. 9.7. Total catch of main pelagic fishes in the Black Sea during 1989 ? 2005.

9.3.1. Sprat

Sprat is a self sustaining, one of the most abundant and commercially important pelagic fish species in the Black Sea, and it serves an important food source for larger fishes (Ivanov and Beverton, 1985; Daskalov et al., 1996; Daskalov, 2002). It is distributed over the whole Black Sea, but its maximum abundance takes place in the northwestern region and shelf waters (Ivanov and Beverton, 1985; Fashchuk et al., 1995). In spring, schools migrate to coastal waters for feeding. In the summer, sprat stays under the seasonal thermocline forming dense aggregations near the bottom during the day and in the upper mixed layer during the night (Ivanov and Beverton, 1985).

Sprat reaches maturity at 1 year and reproduces during the whole year, but its peak spawning takes place between November and March. The spawning size is strongly controlled by winter hydroclimatic conditions and plankton blooms (Simonov et al., 1992; Daskalov, 1999). Its reproductive niche is therefore situated to ensure optimal concentration and retention for eggs and larvae. Eggs and larvae are mostly concentrated near the shelf edge and within the central cyclonic gyres with relatively stable subsurface layer (20 ? 50 m) (Arkhipov, 1993; Fashchuk et al., 1995).

Its recruitment population was found to be weakly dependent on the parental stock biomass and correlated negatively with SST and river discharge but correlated positively with the wind stress (Daskalov, 1999). Its spawning during the winter and spring in deeper layers was also relatively unaffected by M. leidyi because of its low biomass and therefore weak food competition and predation impacts on sprat eggs and larvae. In summer, the juvenile and adult sprat populations leave the upper warmed layer and thus avoid severe competition for food with other plankton-consumers including M. leidyi. During this period their preferred food consists mainly of the cold-water Calanus and Pseudocalanus copepod species living below the cold intermediate layer of the water column. It should be noted that this prey is also available to M. leidyi feeding as they migrate to the thermocline at night for their daily feeding where they can be consumed by the ctenophore. This can partly explain the reduction of the sprat stock in the early 1990s of the Mnemiopsis population outburst. As with the other commercial stocks, heavy overfishing took place before and during the M. leidyi outbreak as well, which should aggravated the stock depletion (Prodanov et al., 1997; Daskalov, 1998). In addition to M. leidyi, the jellyfish Aurelia aurita distributed in deeper waters has a strong trophic interference with sprat. This may explain the coincidence between the declining phase of sprat recruitment and biomass and the peak abundance of A. aurita during the 1980s (Daskalov, 2003; Shulman et al., 1994).

Sprat has always been subject to both artisanal and commercial mid-water trawl fisheries. The regular pre-recruit surveys were performed by the former USSR in collaboration with Bulgaria and Romania from the early 1960?s to 1993 (Tkacheva and Benko, 1979; Ivanov and Beverton, 1985; Arkhipov, 1993; Prodanov et al., 1997). The long-term monitoring of sprat fat content for at least 30 years has been performed by Shul?man et al. (1994). Data on catches (often monthly) have been collected by the countries since the early 20th century. Size and age compositions have been regularly assessed (weekly and monthly) based on samples from the commercial landings or research survey. CPUE has been monitored for different vessel type, fleets, and gear since the 1980s (Daskalov et al., 1996). Research surveys however have been limited in recent years because of financial constraints in many research institutes in the region.

Time-series of the main stock parameters based on catch-at-age stock assessment models (Daskalov et al., 1996; Daskalov 1998; Daskalov et al., 2007) are shown in Fig. 9.8. A quasi-decadal cyclic pattern dominates the recruitment abundance time series. Maxima of recruitment and biomass occurred in the mid-1970s and mid-1980s. Its maximum catch was recorded in 1989, leading to highest fishing mortality prior to the stock collapse. The combination of low recruitment and excessive fishing as well as the Mnemiopsis outburst were the major causes of the 1990 stock collapse since the survey indices, age and size composition consistently showed a drop in recruitment, biomass, mean size, and age (Daskalov and Prodanov, 1994; Prodanov et al., 1997; Daskalov, 1998).

After the 1990 stock collapse, sprat recruitment, biomass and catches started to increase, and the stock reached the previous peak-level recorded in the 1980s by the mid-1990s and even higher stock size at 2005. The catch, however, stayed at relatively low level because of the stagnated economies of Bulgaria, Romania and Ukraine, although the fishing mortality increased from 0.1 in 1990 to 0.3 in 2000. Consequently, the catch attained its former level in the 1980s after 1995 and reached ~70 000 tons in 2001 ? 2005. The decreasing CPUE and mean catch size in Bulgarian and Romanian fisheries in 2006 ? 2007 indicate that the current level of fishing pressure might be too strong for the size of exploited stock biomass and therefore further catch limitations may be needed.

Fig. 9.8. Time-series of recruitment, spawning stock biomass (SSB), catch and fishing mortality of Black Sea sprat.

9.3.2. Black Sea anchovy

Two different anchovy populations exist in the Black Sea: the Black Sea and the Azov Sea anchovies (Ivanov and Beverton, 1985). The latter reproduces and feeds in the Azov Sea and hibernates along the northern Caucasian and Crimean coasts. The stock of the former species is of bigger ecological and commercial importance and the information given below concerns only this stock. Anchovy plays a crucial role in the Black Sea pelagic food web as a prey of many predators such as bonito, blue fish, horse mackerel, dolphins, and the others. It is also an important consumer of zooplankton, especially when the stock is large; thus they act as a predator of zooplankton and competitor of other planktivores (Daskalov et al., 2007).

The Black Sea anchovy is distributed over the whole Black Sea. In October ? November, it migrates to the wintering grounds along the Anatolian and Caucasian coasts and forms dense wintering concentrations until March and becomes subject to intensive commercial fishery. It occupies its usual spawning and feeding habitats across the sea in the rest of the year with preferentially in the shelf areas including the northwestern part of the sea being the largest and most productive shelf (Faschuk et al., 1995; Daskalov, 1999).

Anchovy reaches maturity several months after spawning that takes place during the summer within the warm surface mixed layer in coastal and shelf waters (Arkhipov, 1993; Fashchuk et al. 1995).? Eggs and larvae are retained in coastal regions protected from offshore waters by thermohaline fronts. A large convergence zone formed in the northwestern and the western shelf (the main anchovy spawning area) due to the River Danube inflow favors fish offspring retention.

Anchovy is subject to both artisanal (with coastal trapnets and beach seines) and commercial purse-seines fishery on their wintering grounds. The total anchovy standing stock biomass (SSB) in the Black Sea until 1993 has been assessed using the catch-at-age data in the VPA method (Prodanov et al., 1997). Its more recent changes (after 1993) was estimated using a linear regression between logarithmically transformed SSB and CPUE data of the Turkish purse seine fleet and using the fishing mortality estimation as the ratio of landings and SSB (Daskalov et al., 2007).

Time-trajectories of abundance, catch and fishing mortality shown in Fig. 9.9 reveals pronounced decadal fluctuations as in the case of sprat. The increase in biomass and catch during the 1970s and 1980s was promoted by the expansion of powerful trawl and purse seine fishing fleets in Turkey and thus a steady increase in fishing effort (Anon, 1997; Gucu, 1997). During the years 1974 to 1980, the anchovy stock (largely formed by juveniles of the age 0.5 year) showed upward trend increasing from 800 to 1600 ? 1800 thousand tons. The anchovy catch also increased from 152 to 460 thousand tons but the rate of removal did not exceed 50% of the stock (Prodanov et al., 1997). After the 1981/82 fishing, the limit of fishing mortality for safe stock exploitation (F0.1) has been systematically exceeded (Shlyakhov et al., 1990), causing an average annual reduction of 7% over 1981-1986. The high catches were however maintained by the relatively large reproductive stock. First signs of overfishing appeared after 1984 (Shlyakhov et al., 1990) when anchovy shoals were difficult to be found and the fishery enterprises incurred losses. However, the real catastrophe happened after 1986, when the stock shrunk from 1200 to 500 thousand tons in two subsequent years. Catches during the 1986/87 and 1987/88 remained high, at the level of 452 ? 469 thousand tons, but in the following 1988/1989 fishing season the catch suddenly dropped to 188 thousand tons. The annual rate of stock reduction was 25% for 1987 and 44% for 1988 on average 29% for 1987 ? 1988. The fat content was lower by 40 ? 60% than the previous years. Then, the stock experienced an abrupt decline to less than 300 thousand tons in 1990 that was the lowest level over the period 1967 ? 1993. The fishing effort and fishing mortality also dropped subsequently because of decreasing profitability of fishing. During the collapse phase the size/age structure of the catch shifted toward a predominance of small, immature individuals (Prodanov et al. 1997; Gucu 1997; Mikhailov and Prodanov, 2002). In 1995 ? 2005, the stock partially recovered and catch increased to 300,000 ? 400,000 tons (Fig. 9.9), but because the fishing effort and catch remained relatively high (Zengin, 2003), the exploited biomass could not reach its levels in the 1980s. Anchovy compete for food with M. leidyi (Grishin et al., 1994) and this competition probably further affected the anchovy population growth (Oguz et al., 2008).

Fig. 9.9. Time-series of recruitment, spawning stock biomass (SSB), catch and fishing mortality of the Black Sea anchovy.

Simonov et al. (1992) and Panov and Spiridonova (1998) have found that anchovy abundance and aggregation behavior depended on hydro-climatic factors. They used some climate indices like SST at Batumi and atmospheric circulation to identify climatic regulation of the anchovy stock. As in the case of sprat, the generalized additive modeling (GAM) related favorable anchovy reproduction to high stratification, high SST, low wind stress as well as biological production expressed by the phosphate concentration as a proxy variable (Daskalov, 2003). Probably the strongest environmental effect on anchovy stock by the end of the 1980s was the food competition with and predation by the invasive ctenophore M. leidyi as supported by the modeling studies (Oguz et al., 2008). The initial outbreak of M. leidyi was reported in 1988-89 in the Black and Azov Seas. It appears that the catastrophic reduction of the Black Sea anchovy stock in the late 1980s was due to the combined action of two factors: the excessive fishing and M. leidyi outburst (Grishin et al., 2007). The total loss from the anchovy catch over the years 1989-1992 due to M. leidyi outbreak can be roughly estimated of about 1 million tons causing estimated losses of US$16.8 million (Knowler, 2005). Damage by M. leidyi to the anchovy population was most likely done through food competition, as unusually low levels of the summer food zooplankton have been observed in the top 50m layer in the early 1990s (Grishin et al., 2007; Oguz et al., 2008). Anchovy larvae could also be affected by M. leidyi predation. Mass appearance of anchovy larvae in the plankton occurred in July and August during the M. leidyi biomass seasonal peak (Grishin et al., 2007). M. leidyi was capable of consuming a daily ration several times greater than its own weight (Lipskaya and Luchinskaya, 1990; Grishin, 1994). Its food spectrum was quite wide and included anchovy eggs and larvae as well (Tsikhon-Lukonina and Reznichenko, 1991). There was an overlap in the distributions of anchovy larvae and M. leidyi, even though anchovy larvae were predominantly found in the narrow coastal zone while the ctenophore was also distributed further offshore.

The state of the anchovy stock has improved after the collapse in 1990s, and in 2000-2005 the catches reached ~300 thousand tons. However, the anchovy catch dropped substantially in 2006 indicating a distressed stock condition (M. Zengin, personal communication).? The other possible cause of the drop in anchovy stock include climatic effects (higher water temperature may cause a dispersal of fish schools making them less accessible to the fishing gears) and abundant predators (bonito). Given the strong natural variability, transboundary migratory behaviour, and sensitivity to various environmental impacts, the protection and sustainable use the anchovy resource can be achieved only by coordinated international management and regulation based on sound scientifically grounded stock assessment.

9.3.3. Horse mackerel

The Black sea horse mackerel is a subspecies of the Mediterranean horse mackerel Trachurus mediterraneus. It is a migratory species distributed in all over the sea (Ivanov and Beverton, 1985; Fashchuk et al., 1995). In the spring, it migrates to the north for reproduction and feeding. In the summer, it is distributed preferably in the shelf waters above the seasonal thermocline. In the autumn, it migrates towards the wintering grounds along the Anatolian and Caucasian coasts (Ivanov and Beverton, 1985). It matures at an age of 1 ? 2 years during the summer, which is also the main feeding and growth season. It spawns in the upper layers, both in the open part of the sea and near the coast (Arkhipov, 1993; Fashchuk et al., 1995). Eggs and larvae are often found in areas with high productivity (Daskalov, 1999; 2003).

The horse mackerel (Trachurus mediterraneus) fishery operates mainly on its wintering grounds in the southern Black Sea using purse seine and mid-water trawls. The horse mackerel of age 1-3 years generally prevails in the commercial catches, but strong year classes (for example, the 1969 year class) may enter into exploitation at the age of 0.5 year. Over the last 40 years, highest horse mackerel catches were reported in the years preceding the M. leidyi outbreak (Prodanov et al., 1997; FAO, 2007). The maximum catch of 141 thousand tons was recorded in 1985, from which ~100 thousand tons were caught by Turkey (Prodanov et al., 1997). In the next four years catches remained at the level of 97 ? 105 thousand tons. In the period 1971 ? 1989, the stock increased, although years of high abundance alternated with years of low abundance due to year class fluctuations, typical of this fish (Fig. 9.10). VPA estimates showed that the stock was highest in 1984-1988 (Fig. 9.10). According to Bryantsev et al. (1994) and Chashchin (1998), the intensive fishing in Turkish waters in 1985 ? 1989 led to overfishing of horse mackerel population and reduction of the stock and catches in the subsequent years. A drastic decline in stock abundance occurred after 1990 when the stock was diminished by 56%. In 1991 the horse mackerel stock dropped to a minimum of 75 thousand tons and the catch dropped to 4.7 thousand tons that was a twenty fold reduction compared to the average annual catch in 1985 ? 1989.

In contrast to anchovy and sprat, the horse mackerel stock still remained in a depressed state. The horse mackerel fishery was extremely limited in the former USSR countries during 1992 ? 1998 because of the lack of fishable aggregations on the wintering grounds. Small quantities of horse mackerel were caught with trap-nets in coastal areas of the Crimea and Caucasus. In Turkish waters, horse mackerel catch in 1994 ? 2006 were 9 ? 11 thousand tons, i.e. at the level of the years 1950 ? 1975 before the start of industrial fishing.

The horse mackerel recruitment has been highly variable that therefore supported sporadic year-class strength (Fig. 9.10). The influence of a strong year-class can be traced through biomass increase in the subsequent one-two years. The relationships with selected environmental variables (Daskalov, 1999; 2003) suggested a strong negative correlation with surface temperature (SST) as also reported by other studies (Mikhayluk, 1985; Simonov et al., 1992). It may appear surprising for a warm-water summer spawning species to correlate with cold SST. The effect of the wind stress was significant and generally positive. These results indicated that horse mackerel recruitment has been more abundant in years with increased physical forcing and enrichment.

During 1985 ? 1993, a relatively successful recruitment was recorded only in 1988 (Fig. 9.10). Despite its coincidence with the first year of M. leidyi outbreak, the juveniles from this cohort were sufficiently well-supplied with food. As the first outburst of M. leidyi occurred in the autumn of 1988, the summer zooplankton maximum production did not suffer much from the devastating effect of M. leidyi. The copepods Oithona nana and Oithona similis which constituted the main food of larval horse mackerel (Revina, 1964) were especially abundant. However, the favorable trophic conditions for larvae in summer 1988 failed to ensure the formation of a strong year-class because juveniles were faced with strong feeding competition with M. leidyi further in the year. Sharp decline in Oithona under the predation pressure of M. leidyi in the subsequent years (Shushkina and Musaeva, 1990; Vinogradov et al., 1993) affected the survival of horse mackerel. Dietary studies of juvenile and adult horse mackerel (Revina, 1964) have shown that both the habitat diet of juvenile horse mackerel and M. leidyi overlapped; therefore the strong feeding pressure by M. leidyi on zooplankton directly affected larval and juvenile horse mackerel.

9.3.4. Ecosystem effects on pelagic fisheries

Over the decades, fishing has become a leading anthropogenic stressor, affecting not only fish stocks but also triggered large-scale ecosystem effects such as trophic cascades and regime shifts characterized by sudden, irreversible switches (Daskalov et al., 2007). Overfishing in combination with fluctuating climate was recognized as main causes of the fisheries collapses (Oguz and Gilbert, 2007). Deteriorating environment and alien introductions exacerbated the problem. Overfishing and alien intrusion at high trophic levels drove trophic cascades and switched dominance from valuable fisheries resources to an excess of jellyfishes and microalgae. Interaction between environmental, biological and anthropogenic factors generated feedbacks resulting in harmful plankton blooms, hypoxia, and hydrogen sulphide production, adversely affecting the ecosystem as a whole and fish stocks in particular. The complex nature of ecosystem responses to human activities calls for more elaborate deterministic-based management approaches than currently provided by traditional environmental and fisheries assessment methodologies.

Fig. 9.10. Time-series of recruitment, spawning stock biomass (SSB), catch and fishing mortality of the Black Sea horse mackarel.

9.4. The state of populations of key demersal fishes

From the Black Sea fisheries perspective, the most important demersal fish species are whiting (Merlangius merlangus), picked dogfish (Squalus acanthias), turbot (Psetta maxima), striped, red mullets (Mullus barbatus, M. surmuletus), and four species of family Mugilidae, including so-iuy mullet (Mugil soiuy). The total catch of these demersal fish species in 1996?2005 was lower on the average than in 1989 ? 2005 and had tendency of reduction after 2000 (Fig. 9.11).

Fig. 9.11. Total catch of main demersal fishes in the Black Sea during 1989 ? 2005.

9.4.1. Whiting

In the Black Sea, whiting is one of the most abundant species among the demersal fishes. It does not undertake distant migrations, spawns mainly in the cold season within the whole sea. Whiting produces pelagic juveniles, which inhabits the upper 10-meter water layer for a year. The adult whiting is cold-living species at temperatures 6 ? 10? С (Shlyakhov, 1983). Species younger than 6 years old dominate the populations, and older year classes are found rarely in catches. Dense concentrations are formed by 1-3 year old fishes at depths up to 150 m, most often at the depth range 60 ? 120 m (?zdamar et al, 1996; Shlyakhov and Charova, 2003).

In Bulgaria, Georgia, Romania, the Russian Federation and Ukraine, whiting was rarely a target species and collected mainly as by-catch during trawl fisheries or non-selective fisheries with fixed nets in the coastal sea areas. This fishery was most developed in Romanian waters. In 1996 ? 2005, the total mean annual catch of whiting by Black Sea countries (except Turkey) according to the data of official statistics submitted to FAO was less than 0.6 thousand tons (Table 9.4). Whiting landings by-caught in larger quantities during target trawl fisheries for sprat and other fishes in Bulgaria, Georgia, Romania and the Russian Federation were specified in the official reports of these countries. Thus, the whiting by-catch in the waters of Ukraine in 1996 ? 2002 was assessed in the range of 0.65 ? 1.8 thousand tons (Shlyakhov and Charova, 2003). On the other hand, by-catches of small-sized whiting populations were often not graded and merely discarded (although it is prohibited by the Regulations of Fisheries) or recorded in statistics as sprat.

In the vicinity of southern coast, whiting concentrations are more stable.? Turkey is the only country in the region to conduct the target trawling fisheries for this fish with permission between September and April within offshore areas outside the 3 miles zone from the coast.? Among by-catch fishes in the Turkish fisheries, whiting usually is therefore ranked third or fourth. Its annual catch varied from 6 thousand tons to 19 thousand tons during 1996 ? 2005, making on the average 10.8 thousand tons. As compared with 1989 ? 1995, when the mean annual catch of whiting was 17.6 thousand tons, the tendency towards reduction of both its catches and CPUE is observed (Fig. 9.12).

Using the VPA method, Prodanov et al. (1997) produced assessments for whiting abundance and biomass for the period of 1971 ? 1993. No such basin-scale assessments however existed for 1996 ? 2005, except for the western Black Sea excluding the western Turkish coastal waters (Prodanov and Bradova, 2003). According to this latter assessment, whiting biomass in 1997 was assessed as 121 thousand tons, which was comparable with the long-term mean after decline in 1990 ? 1991 (Fig. 9.14).

Table 9.4. Whiting and picked dogfish catches in the Black Sea according to the official statistics. The last three rows provide the average catches for the periods indicated in the subscripts.

Year

Whiting

Picked dogfish

BG

GEO

RO

RF

TR

UKR

BG

GEO

RO

RF

TR

UKR

1989

0

5

2739

7

19283

579

28

217

30

135

4558

1191

1990

0

70

2653

235

16259

87

16

128

45

183

1059

1330

1991

0

82

59

210

18956

24

21

18

26

67

2017

755

1992

0

70

1357

37

17923

0

15

14

52

15

2220

595

1993

0

172

599

2

17844

5

12

131

6

5

1055

409

1994

0

187

432

125

15084

64

12

45

2

11

2432

148

1995

0

146

327

91

17562

17

80

31

7

90

1562

67

1996

0

223

389

11

19326

3

64

71

0

15

1748

44

1997

0

58

441

10

12725

29

40

1

0

9

1510

20

1998

0

53

640

119

11863

55

28

550

0

6

855

38

1999

0

41

272

184

12459

18

25

18

0

9

1478

94

2000

0

45

275

341

15343

20

102

21

0

12

2390

71

2001

8

32

306

642

7781

18

126

27

0

27

576

134

2002

16

37

85

656

7775

9

100

65

0

19

316

97

2003

13

45

113

93

7162

21

51

40

0

29

1840

172

2004

2

29

118

55

7243

43

47

31

0

34

111

93

2005

3

37

105

49

6007

30

15

45

0

17

102

74

Y89/95

0

105

1167

101

17559

111

26

83

24

72

2129

642

Y96/05

4

60

274

216

10768

25

60

87

0

18

1093

84

Y00/05

7

38

147

306

8552

24

74

38

0

23

889

107

Along the eastern coast of Turkey in 1990 ? 2000, more than 80% of landings of whiting were caught by trawl (Zengin, 2003).?? The research on trawl fisheries in the vicinity of Samsun indicated that as much as 75% of whiting trawl catches were discarded in 2005 (Knudsen and Zengin, 2006) due to their small size average length (Fig. 9.13).

In the Russian sector of the Black Sea, trawl surveys showed that stocks of whiting and other Gadidae (Gaidrosparus mediterraneus) were estimated about 7.6 ? 8 thousand tons, and the total annual allowable catch (TAC) for whiting was 2 thousand tons (Volovik and Agapov, 2003). The corresponding assessments for 1999 ? 2005 given in Table 9.5 testify rather high stable level of biomass in the Russian waters with an average value of 6.6 thousand tons.? If the whiting portion of total by-catch is assumed to be 9% of sprat catch in 1996 ? 2005 (as in Bulgarian case), the average annual capture of whiting is assessed as 1.2 thousand tons that, in agreement with the estimate by Volovik and Agapov (2003), suggests under-exploitation of whiting resources.

Fig. 9.12. Long-term changes of CPUE for three demersal species in Turkish waters of the Black Sea in 1989 ? 2005 (from the TDA Technical Task Team National Experts ? Turkey Report, Duzgunes, 2006).

Fig. 9.13. Whiting landings and average length of whitings harvested in the eastern Black Sea region of Turkey. (Taken from Knudsen and Zengin, 2006).

Along the Turkish coasts, the total biomass of whiting in local trawling areas was estimated by A. İşmen (2003). The highest biomass of 30 thousand tons was found between Sinop and Sarp (eastern Black Sea), which is the area closed to trawl fishing in 1992. The biomass between Sinop (central Black Sea) and İğneada (western Black Sea) was estimated within the range of 1.1 ? 1.7 thousand tons in 1990. But, there are no similar published assessments for the period of 1996 ? 2005. It is therefore more difficult to identify the present state of rather intensively exploited whiting stocks in the Turkish waters. However, the change of mean length of whiting from 16 ? 20 cm range in 1989 ? 1995 to 14 cm in 2000, 12 cm in 2003 and 11 cm in 2005 highly likely implies an intensive whiting fishery within the recent years as further supported by independent statistical-based studies conducted by Gen? et al. (2002) and İşmen (2003). Thus, whiting stock in the waters of Turkey may be characterized as excessively exploited. The main reason for whiting overfishing in Turkey may be the lack of any limitation for annual catch sizes and/or fishing efforts.?

Fig. 9.14. Whiting biomass by age groups (in thousand tons) in the western part of the Black Sea during the period of 1971 ? 1997. (Taken from Prodanov and Bradova, 2003).

Table 9.5. Whiting stock in the Russian waters in the northeastern Black Sea (thousand tons) (taken from the TDA Technical Task Team National Experts ? Russian Federation Report, 2006).

Years 1999 2000 2001 2002 2003 2004 2005
Stock

7.1

7.6

7.0

5.8

6.85

6.0

6.0

For 1992 ? 1995 whiting biomass in the waters of Georgia, the Russian Federation and Ukraine was identified within the range 64 ? 103 thousand tons, on the average 82 thousand tons. The range and the average stock size for 1996 ? 1998 were 68 ? 77 thousand tons and 72 thousand tons, respectively (Shlyakhov and Charova, 2003). In 1992 ? 1995 whiting biomass in the Ukrainian waters changed from 43 to 70 thousand tons, on average 54 thousand tons. For the subsequent decade, they were 40-68 thousand tons and 52 thousand tons, respectively (Shlyakhov, Charova, 2006). These data testify rather high inter-annual fluctuations but rather stable average level of whiting biomass in the regions where whiting specialized fisheries was almost absent and trawling fisheries were not conducted on the grounds with the densest whiting distributions. In the Ukrainian sector, whiting catch in 1996 ? 2005 did not exceed 30% of allowable catch (Shlyakhov, Charova, 2003; 2006). Therefore resources of whiting are underexploited in Ukraine.

These official statistics provided by the Black Sea countries however may not reflect the true harvesting that may indeed higher. For this reason, the assessments of the stock abundance made from the scientific trawl surveys or estimates produced using the obligatory correction of unregistered catch seem to be more realistic. Using one latter type data set, an independent assessment of whiting average annual capture in 1996 ? 2005 on the shelf from the border with Turkey to the Danube estuary was computed as 670 tons that turned out to be 2.4 times higher than the value of 278 tons based on the official catch statistics. Thus, it appears that the official statistics underestimates considerably the real catch.

Prodanov and Bradova (2003) and Radu et al. (2006) noted the important role of improved ecological conditions of the Black Sea environment after 1993 for the tendency of increasing whiting biomass along the Bulgarian and Romanian coasts. In their opinion, rehabilitation of small-sized pelagic fish stocks reduced the pressure on whiting populations, thus leading to a slight recovery of their stock. Another likely cause of rehabilitation of the whiting stocks may be naturally-caused year-to-year variations in their reproduction, length-weight and age parameters (Shlyakhov, 1983), whereas intensity of whiting fisheries along the coasts of Bulgaria and Romania has been too low to exert major effect on its abundance and biomass.

Table 9.6. Fish stocks protection measures for whiting implemented by the Black Sea countries.

Fish Stocks Protection Measures applied in the Black Sea coastal states

Coastal states

BG

GEO

RO

RU

TR

UA

Periodic ban

+

+

+

+

+

+

Total Allowable Catch (TAC)

+

+

+

+

+

Total Permitted Catch (Limit)

+

+

Minimum admissible size

+

+

+

+

+

+

Periods for fishing bans

+

+

+

+

+

+

Fishing Free Zones

+

+

+

Prohibited fishing gears

+

+

+

+

+

+

Allowable mesh size for nets

+

+

+

+

+

+

In all the Black Sea countries, protection measures for fish stocks were adopted including whiting (Table 9.6). However, implementation of TACs, quotas without efficient enforcement of the measures does not avoid the overfishing problem and other negative impacts of fisheries on exploited species. On the basis of the assessments of national experts in fisheries, the main transboundary threats for whiting are listed as follows.

Lack of regional cooperative management of fisheries. For the group of non-migratory fishes with shared stocks where whiting belongs, management of shared stocks can be successful only with rather developed regional cooperation. It requires a unique methodological approach in all the aspects of stock assessment (methodology, collection, processing and analysis of common data set, etc.), agreed measures of fisheries regulation (terms and grounds of banning, permitted fishing gears, mesh size for nets, fishable length of fishes, allowable by-catches for juveniles, etc.), agreed system of satellite monitoring for commercial fishing vessels and many other aspects.

Illegal fishing and use of destructive harvest techniques. Illegal fishing has never been and will not be a real threat for whiting population.? But the use of destructive harvest techniques by trawls due to high by-catch capture rate of the year 0+ small-sized populations is a real threat. In addition to its direct threat on the reduction of whiting recruitment, it may indirectly cause wrong TAC assessments and thus false decision-making.?

Eutrophication and pollution. The alterations of trophic flow structure due to eutrophication-induced effects in the ecosystem may be critical for whiting populations because zooplankton, small pelagic fishes and benthos organisms (crustaceans and Polychaetae) are among their important diet. In turn, whiting is an important prey species for large predators, dolphins and fish-consuming birds. Whiting juveniles and bottom-dwelling whiting at age less than 2 years old distributed mainly in shallow depths are the most vulnerable for eutrophication effects.

9.4.2. Picked dogfish

Picked dogfish inhabits the whole Black Sea shelf at water temperatures 6 ? 15? С. They migrate in the form of large schools for feeding and overwintering on anchovy and horse mackerel to the Crimean, Caucasus and Anatolian coasts in autumn. In the Ukrainian and Romanian grounds of whiting and sprat concentrations, abundant wintering concentrations of picked dogfish are also observed at depths from 70-80 m to 100 ? 120 (Kirnosova and Lushnicova, 1990). Reproductive migrations of picked dogfish take place in spring and autumn at coastal shallows at 10 ? 30 m depths zones (Maklakova and Taranenko, 1974). The major grounds for reproduction are the Crimean coastal waters such as the Karkinitsky Bay, the vicinity of Kerch Strait, and the Feodosia Bay. Picked dogfish belongs to long-living viviparous fish; therefore reproduction process includes copulation and birth of fries. Near the coasts of Bulgaria, Georgia, Romania, Russian Federation and Ukraine the maximum copulation takes place in March ? May. Two peaks of birth of juveniles can be distinguished ? spring (April-May) and more powerful ? summer-autumn (August ? September) at water temperature range of 12 ? 18?С (Serobaba et al., 1988). The picked dogfish population includes 19 year-classes and among commercial fish species of the Black Sea this species is inferior only to sturgeons in duration of life cycle.

It is not a target species of fisheries, and mostly caught as by-catch in trawl and purse seine operations mainly during their wintering period. The largest catches of picked dogfish are along the coasts of Turkey. In the Ukrainian waters, picked dogfish is mainly harvested in spring and autumn months by target fishing with nets of 100 mm in mesh and with long-lines as well as during sprat trawl fisheries as by-catch. For the whole population of picked dogfish in the Black Sea stock assessments for 1972 ? 1992 were produced by the VPA method (Prodanov et al., 1997), and trawl surveys and mathematical modelling (Shlyakhov and Charova, 2006) (Table 9.7). In 1989 ? 2005, picked dogfish stock on the Ukraine shelf reduced gradually. Such dynamics of the stock agrees well with Turkish data concerning variations of CPUE (see Fig. 9.15). According to the assessments of Prodanov et al. (1997), the picked dogfish stock increased until 1981 due to increased abundance of their main dietary species (whiting, sprat, anchovy and horse mackerel), and then started decreasing due to intensification of the dogfish fishery.

Evidently, the role of fisheries in reduction of picked dogfish stock was over-estimated at that time. In fact, for 1979 ? 1984 the mean annual capture from the stock in the Black Sea made up 8254 tons or about 4% of the initial stock, and it reduced to 3.5% in 1989 ? 1992 (Kirnosova, 1990). Even taking into account unreported catches of picked dogfish, which in late 1980s seemed not to exceed the official catch (at least in the waters of Ukraine ? Shlyakhov and Charova, 2003), real capture was not excessive. The mean length of picked dogfish in the northwestern Black Sea in trawl catches in 1989 ? 2005 did not reduce and even increased (Fig. 9.15), that do not imply overexploitation of this species. The causes of reduction of picked dogfish stock should therefore be related to the changes in the Black Sea ecosystem due to pollution and subsequent progressive deterioration of reproductive ability of females (Shlyakhov and Charova, 2003). In the 1970-1980s, the mean number of yolk ovocytes and embryos for one female was 22 and14, respectively, and they were reduced to 19.5 and 12.4 by late 1990s. As a result, the abundance of recruits reduced year by year.

Fig. 9.15. Biomass of picked dogfish in the Black Sea-BBS (Prodanov et al., 1997), in the waters of Ukraine? BUA (Shlyakhov, Charova, 2006) and the mean standard length (l average) in trawl catches of picked dogfish in the northwestern part of the sea: Trend lines are shown for the BUA and l average data series.

Table 9.7. Commercial stock of picked dogfish in the Black Sea and along the coast of the former USSR and in the water of Ukraine in 1989 ? 2005, thousand tons

Years Whole Black Sea shelf

Waters of Ukraine, the Russian Federation and Georgia

Waters of Ukraine

VPA

Trawl

survey

Modeling

Trawl survey

Modeling

1989

117.8

58.5

63.5

34.6

-

1990

112.9

58.7

63.2

48.8

-

1991

97.9

17.2/69.9*

64.0

14.4/58.5*

-

1992

90.0

62.9

60.3

56.9

-

1993

-

-

57.1

30.2

-

1994

-

-

52.9

36.0

42.1

1995

-

-

-

-

37.6

1996

-

-

-

-

32.1

1997

-

-

-

-

31.0

1998

-

-

-

32.0

30.8

1999

-

-

-

-

28.0

2000

-

-

-

-

24.3

2001

-

-

-

-

22.3

2002

-

-

-

-

21.0

2003

-

-

-

-

22.1

2004

-

-

-

-

22.3

2005

-

-

-

-

21.0

* stock assessment is reduced to the average area of the registration (survey) zone

The main threats for the Black Sea picked dogfish resource with transboundary significance are the same as for whiting. One more threat may be added to that list:

Pollution from land based sources (rivers) and direct discharges (inshore area). As a long-living predator as compared with other fishes in the Black Sea, picked dogfish has the ability to accumulate toxic pollutants ? heavy metals (mercury, arsenic, lead, copper, cadmium and zinc) and chlorine organic compounds (including and its metabolites, polychloride biphenyls, etc.).

9.4.3. Turbot

Turbot occurs all over the shelf of the Black Sea. It is a large-sized fish with long life cycle; it reaches length of 85 cm, weight of 12 kg and age of more than 17 years old in the Black Sea (Svetovidov, 1964). Turbot fecundity is very high, up to 12.8 million of eggs per year. Larvae and fries in the first two months inhabit in the pelagic zone, feeding on zooplankton. Adults feed on fish mainly, both on demersal (whiting, red mullet and gobies), and with pelagic species (anchovy, sprat, horse mackerel, shad) species. Diet of turbot also includes crustaceans (shrimps, crabs, etc.), mollusks and polychaetes. Like whiting, it does not undertake distant transboundary migrations. Local migrations (spawning, feeding and wintering) have a general direction from the open sea towards the coast or from the coasts towards offshore. It matures in majority at the age of 3 ? 5 years in the waters of Bulgaria (Ivanov and Beverton, 1985), at the age of 5 ? 6 years in the waters of Ukraine and the Russian Federation (Popova, 1967). It spawns in spring, from the late March until the late-June, at water temperature range 8 ? 12?С. The peak of spawning occurs in May at depths from 20 ? 40 to 60 m. After the spawning, turbot moves downwards to the depths 50 ? 90 m and maintains low-activity life with limited feeding until the early autumn. In autumn turbot returns coastal waters again, where it feeds intensively. For wintering it migrates to the depths from 60 m to 140 m.

In all the Black Sea countries, turbot is one of the most valuable fish species. Its target fisheries is conducted with bottom (turbot) gill nets with minimum mesh size 180 mm in the waters of Bulgaria, Georgia, Romania, the Russian Federation and Ukraine (Prodanov et al., 1997) and with minimum mesh size 160 ? 200 mm as well as with bottom trawls with minimum mesh 40 mm in the waters of Turkey (Tonay and ?zt?rk, 2003). Turbot as a by-catch is harvested during target fisheries of other species with trawls, long-lines and purse seines. According to Zengin (2003), 72% of turbot fishing in Turkish waters of the Black Sea has been carried out by bottom gill nets, 26% by trawls and 2% as the by-catch from purse seines. More than 80% of the Ukrainian turbot catches were performed by target fisheries using nets with mesh size 180?200 mm, the rest part mainly corresponded to by-catch. In 1996 ? 2005, the mean annual Turkish turbot catch was 1235 tons, and 177 tons for the rest of the Black Sea countries (Table 9.8). The turbot fishery was completely banned or largely limited by the Total Permitted Catch in all countries except Turkey in the early 1990s and therefore was at a negligible level.

Like for many demersal fish species, the serious problem for estimating the status of turbot population and justifying efficient measures for its fisheries regulation is considerable difference between the recorded statistics and the real catches. According to the expert assessments (Shlyakhov and Charova, 2003), the unregistered annual yield of turbot for Ukrainian waters was in the range of 0.2 ? 0.8 thousand tons in 1992 ? 2002. These assessments are not complete, as they included only the unregistered turbot by-catch during sprat fisheries and poaching (illegal) catches of Turkish vessels. But, this unregistered annual yield was even higher than official turbot statistics.

Table 9.8. Turbot catches in the Black Sea in 1989 ? 2005 in tons. The last three rows show the average catches for the years indicated in the subscripts.

Year

Turbot

BG

GEO

RO

RU

TR

UA

1

0

1449

1990

1

0

9

0

2

915

1992

0

1

19

0

6

1585

1994

0

5

16

60

2

2850

1996

0

17

39

59

1

911

1998

0

14

42

54

2

1804

2000

9

4

80

57

13

2323

2002

11

15

104

41

24

119

2004

7

2

133

13

28

548

Y89/95

1

4

13

56

13

1235

Y00/05

8

13

117

Caddy (2006) interpreted the landing data in terms of trends and suggested the baseline trend before 1989, the decreasing trend in the collapse years 1989-92, gradually increasing trend in 1992 ? 2002, a more pronounced increasing trend in 1998 ? 2002. The landing in 1998 ? 2002 was 70% of the baseline and therefore suggested partial recovery in recent years. If the catch analysis takes into account exploitation of different stock units, the interpretation given by the trend analysis however changes greatly. In the base period (1967 ? 1988) Turkish landings made up 82% of total catches of all the countries. Its fisheries was conducted mainly on local turbot stocks existed in its own waters in 1967-71 and 1985-92, but extended into the western and northwestern stocks within the international waters in 1972 ? 1984 (Acara, 1985). By 1985, the western and northwestern stocks appeared to be overfished; for this reason since 1986 the former USSR imposed banning for turbot fisheries in its waters to which Bulgaria and Romania joined soon but Turkey refused to join to this banning. In 1986 ? 1992 (i.e. at the end of the base period and in the years of collapse) recovery of the stocks took place with the negative trend of landings, as in this period only stocks in the Turkish waters were fished. The positive trend of landings in 1992 ? 2002 and its steep increase in 1998 ? 2002 was explained not only by recovery of turbot stocks in the waters of Ukraine, but by the intensification of illegal fishing of the western and northeastern stocks by Turkish vessels. As indicated by the available studies carried out in different Black Sea countries (Table 9.9), turbot stocks decreased prior to 1989 and a partial recovery of turbot biomass took place in waters of all countries except Turkey as a result of banning and limiting the fisheries by the early?1990s.

Table 9.9. Some studies carried out in the Black Sea regions on turbot stocks.

Researchers Location Years and periods Biomass assessment (tons) MSY or TAC (tons) Methods
Prodanov et al., 1997 Waters of the Black Sea 1989-1990 1991-1992 19100 6200 - LCA Jones? method
Bingel et al., 1996 Southern Black Sea (Sinop-Georgia board) Western Black Sea 1990 1991 1992 1990 124 410 766 130.5 - Swept area method (trawl surveys)
Zengin, 2000 Southern Black Sea (Sinop- Georgia board) 1990 1991 1992 1993 686.3 250.4 222.4 134.3 96.1 26.3 24.5 15.4 Swept area method (trawl surveys)
Prodanov and Mikhailov, 2003 Waters of Bulgaria 2002 Mean ? 352 Initial ? 425 60 LCA Jones? method
Shlyakhov and Charova, 2003 Waters of the Russian Federation 1992 1800 - Swept area method (trawl surveys)
Volovik, Agapov, 2003 Waters of the Russian Federation 2000-2002 1000-1700 100 Swept area method (trawl surveys)
Shlyakhov and Charova, 2003 Waters of the Russian Federation 1992-1994 4280 (1800-5900) - Trawl surveys and Baranov?s modified equation
Maximov et al., 2006 Waters of Romania 2003-2005 427-1066 - Swept area method (trawl surveys)
Shlyakhov and Charova, 2003; 2006 Waters of Ukraine 1992-1995 1996-2002 2003-2005 8830 (8200-10400) 10980 (8400-13700) 9570 (8500-10200) - Swept area method (trawl surveys)
Shlyakhov and Charova, 2003; 2006 Waters of Ukraine 1992-2002 2003-2005 10590 (8200-13700) 8900 (8200-10200) - Trawl surveys and Baranov?s modified equation
Panayotova et al., 2006 Waters of Bulgaria 2006 1440 - Swept area method (trawl surveys)
Raykov et al., 2008 Waters of Bulgaria 2006 1567 - Swept area method (trawl surveys)

Analyzing the state of the stock using official statistics of turbot capture near the coasts of Bulgaria, Prodanov and Mikhailov (2003) concluded that biomass of this species was about 2500 tons in early 60s. By late 1970s biomass reduced to 355 tons as a result of overfishing and deteriorating environment, and to 100 tons in 1993. Applying LCA method, they assessed the turbot stock as 424 tons in 2002. Increased biomass was the consequence of five-year banning for fisheries. However, comparing stock abundance and capture, they determined that the catches were composed by fish size 42 ? 47 cm and 2 ? 4 year old indicating turbot excessive exploitation again. According to the official statistics, landings in 2003 made up 49 tons, and in subsequent two years it reduced to 16 tons and 13 tons respectively. The last assessment indicated the turbot biomass in the Bulgarian waters as 1440 ? 1567 tons in 2006 (Panayotova et al., 2006; Raykov et al., 2007).

Table 9.10. Biomass and catches of the turbot of the Black Sea in the waters of Ukraine in 1996 ? 2006 (tons), mean fishing mortality, relevant to its official catches in 1992 ? 1995 and 1996 ? 2005.

Years Biomass of stocks (B) Catch (Y) for: Total Permitted Catch (Limit) Official landings
Swept area method (trawl surveys) Baranov?s modified equation F0.1=0.15 Fmax=0.20
1996 - 13500 1792 2333 84 39
1997 - 13600 1805 2350 90 42
1998 8400 13300 1440 1875 90 42
1999 - 12600 1672 2177 190 73
2000 - 9600 1274 1659 185 80
2001 9900 10500 1354 1762 370 129
2002 10000 8700 1241 1616 395 104
2003 10000 8900 1254 1633 310 124
2004 8500 8200 1108 1443 350 133
2005 10200 7800 1194 1555 319 129
2006 10400 7600 1194 1555 323 162
1992-95 8871 1177 1533 - 14 Fof = 0.001
1996-05 10094 1411 1744 238 90 Fof = 0.009

The last research on turbot stock in the waters of Bulgaria and Romania pointed to their level of exploitation. In 2005 biomass of this species was assessed as 1066 tons (Maximov et al., 2006). Near the Russian coast, the long-term banning for turbot fisheries (since mid 1980s till mid 1990s) resulted in improvement of the state of northeastern stock. By the end of banning it was assessed as 1800 tons. According to AzNIIRKH research, the state of turbot stock is not stable, but changes occur in a rather narrow range of 1000 ? 1700 tons (Volovik, Agapov, 2003). The observed interannual fluctuations in biomass assessments in 2000s may be caused by re-distribution of turbot between Russian and Ukrainian waters. In the opinion of Russian scientists, overexploitation of turbot in their waters for recent 10 years has not been observed.

Direct assessments of turbot biomass made using the data of trawl surveys near the coasts of Turkey eastwards to Sinop for 1990 ? 1992 differed greatly. According to Bingel et al. (1996) increase in biomass took place in those years, and according to Zengin (2000), on the contrary, reduction in biomass occurred. According to the assessments of Prodanov et al. (1997) on the grounds of cohort analysis of the length composition of catches between 1989 and 1992 turbot biomass reduced 3.1 times in the waters of Turkey, and this tendency agreed well with 3.9 times reduction assessed by Zengin (2000). Composition of Turkish catches was evidence of capture of immature turbot at ages under 4+ that was about 63% in 1990 ? 1995 and 62% in 1996 ? 2000 of the population.

For recent 10 years, continuous set of the published assessments of turbot biomass is available for the waters of Ukraine where the greater part of its western population distributes. Table 9.10 gives the most detailed information on biomass dynamics and potential catch of turbot after 1996.

According to the data of the last trawl surveys proportion of biomass of the western stock and northeastern is close to 9:1, and the percentage of fish from the western stock in the annual catch of Ukraine is even more. As compared with 1992 ? 1995, in 1996 ? 2005 turbot biomass in the Ukrainian waters increased slightly. Trawl surveys undertaken each year since 2001 is the evidence of stable level of turbot biomass in the waters of Ukraine. In 1996 ? 2005 the control measures enabled to avoid overfishing of turbot, and stabilized the length-weight composition of catches in the northwestern Black Sea (Fig. 9.16).

The list and significance of the main threats for turbot resources in the Black Sea are similar to those for whiting. The first place should be given to Illegal fishing and use of destructive harvest techniques. In the broad sense it is not only poaching but deliberate avoidance of adopted measures of regulation by fishermen. This threat is of social and economic character, and not easy to reduce it. An almost equivalent, in experts? opinion, threat is the lack of regional cooperative management of fisheries.

Fig. 9.16. Mean length and weight of turbot in the northwestern Black sea and its landings by Ukraine in 1997 ? 2005.

9.4.4. Striped and red mullets

Two physiologically similar species Mullus barbatus and Mullus surmuletus belong to the family Mullidae. The species M. barbatus is also called as red mullet or striped mullet. In FAO terminology, M. barbatus is also named as striped mullet. For the convenience?s sake we use hereinafter this name to both species of the family Mullidae.

Striped mullet is distributed all over the shelf of Black Sea. It prefers waters with the temperature higher 8? С and salinity more than 17?. Striped mullet reaches maturity in the first-second year of its life. It lives usually until 4 ? 5 years old reaching length of 20 cm and more. Striped mullet spawns in the warm period of time with a maximum in mid-summer. Eggs and juveniles (up to the age of 1.5 months) are pelagic; adults live near bottom, feeding on Polychaetae, crustaceans and mollusks. In the vicinity of the Crimean and Caucasus coasts, it is customarily distinguished in two particular forms ? settled and migratory ones. The latter has higher rate of growth. Migratory form has the greater commercial value, moving to the Kerch Strait and the Sea of Azov for fattening and spawning in spring and coming back to the coasts of the Crimea for wintering.

Due to its taste, the striped mullet is a valuable target species for fisheries. Most of all striped mullet is harvested in the Turkish waters (Table 9.11) where it is the second important target species in the bottom trawling fisheries after whiting. In 1990 ? 2000, around 75% of landings of striped mullet were caught by trawl along the eastern Black Sea coast of Turkey (Zengin, 2003). Its mean annual catch made up 2590 tons and as compared with the previous 7-year period it reduced 46% in 1996 ? 2005 due mainly to decreased catches in the eastern part of the sea. Beginning from 1999, more than half of striped mullet landings have realized on the western Black Sea of Turkey where the proportion of trawl fisheries is much less (Fig. 9.17). To some extent it is the evidence of excessive pressure of trawl fisheries on striped mullet stocks near the Turkish coasts. The years 1989, 1993 and 1996 are identified as particularly abundant years with relatively high catches in the eastern part whereas higher catches in the western part follows with a 2 ? 3 years phase lag (1991, 1996 and 1999).?

Table 9.11. Landings of mullets in the Black Sea according to the official statistics (tons).

Year

Striped mullet

Mullets (Mugilidae)

BG

GEO

RO

RU

TR

UA

BG

GEO

RO

RU

TR

UA

1989

0

0

5

324

6753

0

3

5

8

12

2843

22

1990

0

0

7

132

3507

0

1

19

0

4

1749

6

1991

0

0

25

210

3610

0

7

0

0

2

4026

8

1992

1

0

0

37

2988

5

5

0

0

2

2358

0

1993

0

0

0

0

2877

12

6

0

0

70

4061

0

1994

0

0

5

25

2337

10

6

0

0

70

5112

0

1995

0

0

9

324

4348

13

24

0

1

65

7779

4

1996

0

0

1

76

5419

2

29

3

0

382

12901

12

1997

0

14

3

68

4040

17

30

0

0

480

8680

118

1998

0

11

3

119

2536

26

13

0

0

401

8198

82

1999

0

8

1

92

2989

26

16

9

0

35

9887

211

2000

0

3

2

127

2355

10

15

19

0

85

14189

178

2001

26

22

3

119

1498

19

57

28

1

7

6705

459

2002

33

67

2

47

1651

40

96

73

2

33

4048

187

2003

36

50

3

177

1073

26

34

80

1

312

3711

59

2004

17

35

40

99

1187

16

18

68

3

366

4191

51

2005

1

51

15

92

1649

15

10

74

2

92

3882

91

Y89/95

0

0

7

150

3774

6

7

3

1

32

3990

6

Y96/05

14

28

8

114

2590

22

38

38

1

220

8310

191

Y00/05

19

38

11

110

1569

21

38

57

2

149

6121

171

In the waters of Bulgaria and Romania the striped mullet is not a valuable target species for fisheries. It is harvested as by-catch during trawl fisheries or together with other fishes during non-selective fisheries with trap nets. In 1996 ? 2005 catches of striped mullet in the Bulgarian waters increased slightly. In the waters of Georgia according to the data of official statistics in 1989 ? 1996 catches of striped mullet were absent or was categorized within the ?other fish? group. In 1997 ? 2005, its mean annual catch was equal to 28 tons. According to Komakhidze et al. (2003), the striped mullet was captured recently in higher amounts that provided an indirect evidence of increasing abundance. Along the coasts of the Russian Federation target fisheries of striped mullet are performed mainly with passive fishing gears. The stocks exceeded over 100 tons by 1998, which was mainly related to the reduction of Mnemiopsis leidyi population (Volovik, Agapov, 2003). In 2002, the total biomass was estimated as 1200 tons, exploited biomass as 960 tons and TAC as 200 tons. In the Ukrainian waters, target fishing of the striped mullet was permitted only with beach seines and scrapers; however, the greater part of its catches corresponded to the non-target fishing with bottom traps (Shlyakhov and Charova, 2003). The major share of striped mullet was harvested in autumn in Balaklava Bay, near Sebastopol. The amount of non-registered catches of striped mullet was undefined. The annual determination of limits for striped mullet harvesting was made without TAC, but taking into account the monitoring of the whole status of the population (size and age composition of catches, proportion between the rest and recruitment, etc.). Its value was estimated as 50 ? 60 tons for recent years.

Fig. 9.17. Landings of striped mullet in the Black Sea waters of Turkey (according to data of the TDA Technical Task Team National Experts ? Turkey, Duzgunes, 2006).

9.4.5. Mullets (Mugilidae)

Among 6 species of mullets from family Mugilidae inhabiting the Black Sea, three aboriginal species Liza aurata (Risso), Mugil cephalus L., Liza saliens (Risso) and one acclimatized species Mugil so-iuy Basilevsky (Liza haematocheilus (Temminch et Schlegel) are of commercial value. Mullets are distributed all over the coastal waters and in the estuaries adjacent to the sea. Their migration routes run along the whole coast and via the Kerch Strait (to the Sea of Azov and back). Wintering migrations of mullets are the most intensive in November. Wintering of warm-loving aboriginal mullets takes place in the narrow coastal band and bays at depths less than 25 m. The wintering grounds of so-iuy mullet are not studied well-enough but known to spend winter in the northwestern Black Sea in the vicinity of the Crimean coast, in the Dneprovsky estuary and in other estuaries connected to the sea (Donuzlav, Berezansky, etc.). Often it spends winter under the ice. Spawning migrations of aboriginal mullets from feeding grounds to the Black Sea take place in late August-September. Their stock is the most abundant in the northern Black Sea in the waters of the Russian Federation and Ukraine Crimean-Caucasus.

All coastal countries are engaged in mullet fisheries. Due to their geographical position and wide application of active fishing gears for mullets capture, Turkey has the largest landings (Table 9.11). So-iuy mullet fisheries along the coasts of Anatolia are mainly based on fishing off pre-spawning and spawning concentrations. Vessels with engine power from 5 to 380 Hp are engaged (Knudsen and Zengin, 2006). In other countries, the mullet fisheries are carried out with passive fishing gears with traps of different design.

The separate statistics for catch of mullets by species is not available although the Russian Federation and Ukraine compiled the separate statistic for So-iuy mullet. Lack of separate statistics for catches of mullets, availability of local stocks as well as their un-reporting catch obstructed producing the mullet biomass assessments for the whole Black Sea.

Fig. 9.18.? Biomass and mean length changes of golden mullet in the Crimean waters of Ukraine during 1996-2005.

? Fig. 9.19. Total catch of main mollusks in the Black Sea in 1989 ? 2005.

The 1980s and early 1990s was a period of very low mullet stocks in the Crimean-Caucasus coasts and thus their fisheries were prohibited. Populations of mullets started to be restored only by the late-1990 (Fig. 9.18); however, their renewed fisheries became less intensive. Its stock increase was accompanied by an increase in its total length (Fig. 9.18) that is an additional evidence of improvement of stocks of this fish in the waters of Ukraine. Along the coasts of Caucasus in the waters of the Russian Federation, the state of So-iuy mullet stocks, golden mullet and flathead grey mullet stocks was rather favorable in 2002 to conduct target fisheries within TAC 150 tons (Volovik and Agapov, 2003).

9.5. Commercial mollusks

Among mollusks, the clams (Chamelea gallina, Tapes spp.), Mediterranean mussel (Mytilus galloprovincialis), and sea snail (Rapana thomassiana) have the greatest commercial value. The former two species are harvested only by Turkey and the latter species ? by all the countries of the region except Romania. The capture of mollusks in 1996 ? 2005 has the tendency to increase (Fig. 9.19).

9.5.1. Mediterranean mussel

Among the Black Sea mollusks, Mediterranean mussel (Mytilus galloprovincialis) is the one with highest commercial value. It is one of the most abundant macrozoobenthos species in the Black Sea. It forms the communities along all the coasts from the shoreline to the depth of 55 ? 60 meters.

In 1989 ? 2005 mussel fisheries was developed in Turkey and Ukraine, while its harvesting in the waters of Bulgaria and the Russian Federation was much less, and Georgia and Romania did not harvest this mollusk at all. Comparison of mussel harvesting in 1989 ? 1995 and 1996 ? 2005 demonstrated a major reduction in the waters of Turkey and Ukraine for the last10 years (Table 9.12).

According to the opinion of Turkish experts, Mediterranean mussel banks were seriously affected and production rates were decreased. Recently mussel harvesting in the eastern part has not been conducted. In the Ukrainian waters degradation of the mussel settlements occurred mainly due to the deterioration of the environmental conditions and anthropogenic impacts (Fashchuk et al., 1991). The most abundant settlements of this mollusk were concentrated in the northwestern part. Up to the mid-1970s, mussel biomass in the northwestern Black Sea varied between 8 and 12 million tons. In subsequent years, massive death of bottom organisms was registered almost every year due to the oxygen deficiency in near-bottom water layer. It results in rejuvenation of the mussel population as compared with the preceding period. In 1980s the total mussel stock on the Ukrainian northwestern shelf reduced to 4-6 million tons (Zaitsev, 1992). The juveniles made up the basic population at the age of fingerlings and yearlings, up to 35 ? 40 mm long. In some years juvenile proportion became as high as 75% of the total population.

Up to 1992, on the banks located in the vicinity of the Black Sea Ukrainian coasts, mussel was harvested with drags more than 1000 tons per year. Almost all the mussels were small-sized and were designed for foraging purposes. At present, only ?Mezhvodnoye? bank remained for mussel exploitation. Analysis of the mussel stock status on this bank for the period of observations indicated moderate fluctuations in the range of average amount of 60 thousand tons for mussels of 5 to 70 mm long and 20 thousand tons ? for mollusks of more 50 mm long. Mussel harvesting on this bank is recommended annually for 2 thousand tons; however it never exceeded 0.5 thousand tons after 1992.

9.5.2. Sea snail (Rapana spp.)

This species of mollusk is considered to be R. thomasiana in most Black Sea countries, and the name R. venosa is used rarely for this species. It is thought that sea snail came to the Black Sea with ballast waters from its home places of the Indian-Pacific oceans (Sorokin, 1982). Near the Ukrainian coast sea snail becomes mature at the age of 2 ? 3 old; it lives till 8 ? 9 years and reproduces during the warm period (July ? September). Pelagic larvae of sea snail feed on nanoplankton algae and their adults feed mainly on bivalves of families Cardiidae, Mytilidae, Veneridae, Arcidae and they travel over large distances for feeding. In some periods of a year it buries itself into the ground. Introduction of this predatory mollusk into the ecosystem of the Black Sea turned out to be a catastrophe for oyster biocenoses. Distribution of sea snail is associated with reduction in area and density of mussel settlements, in particular near the coasts of Anatolia and Caucasus. In the Ukrainian waters sea snail destroyed the oyster banks in the area of the Kerch Strait and in Karkinitsky Bay, biocenoses of other mollusks associated with depth down to 30 m suffered as well.

Turkey has been conducting large-scale harvesting of sea snail since the mid-1990s. The other Black Sea countries joined to its fisheries excluding Romania. The Turkish catch remained, however, much higher than other countries, followed by Bulgaria. Their catch increased noticeably during 2000s (Table 9.12). It also became commercially important resource in Bulgaria after 1994. Prior to beginning of its regular harvesting, the biomass on the coastal grounds between Kaliakra and Pomorie was about 2 thousand tons (Prodanov and Konsulova, 1993). Taking into account all the area and the buried part of mollusks, its total biomass was assessed as 7.5 thousand tons. Bottom trawling and dredging were officially forbidden, although these fishing gears were used for the sea snail fishery. According to the assessments of the Private Bourgas Fishery Association, sea snail landings almost 17 times higher than the official report 8557 tons in 2005 (TDA Technical Task Team National Experts ? Bulgaria report, Raykov, 2006).

Table 9.12. Landings of Mediterranean mussel and sea snail in the Black Sea (tons).

Year

Mediterranean mussel

Sea snail (Rapana spp.)

BG

GEO

RO

RU

TR

UA

BG

GEO

RO

RU

TR

UA

1989

0

0

0

26

2637

1128

0

0

0

4

10032

0

1990

0

0

0

9

2544

2189

0

0

0

156

6094

0

1991

0

0

0

88

26

399

0

0

0

11

3730

0

1992

0

0

0

0

5678

449

0

0

0

192

3439

14

1993

0

0

0

0

5914

210

0

0

0

29

3668

3

1994

0

0

0

0

6038

226

3000

0

0

2

2599

5

1995

0

0

0

0

5741

578

3120

700

0

54

1198

303

1996

5

0

0

0

1400

74

3260

711

0

1

2447

376

1997

57

0

0

0

2952

159

4900

118

0

440

2020

476

1998

92

0

0

0

2435

82

4300

0

0

46

3997

369

1999

100

0

0

4

1584

155

3800

0

0

45

3588

619

2000

0

0

0

0

178

111

3800

184

0

182

2140

913

2001

7

0

0

0

17

61

3353

517

0

224

2614

395

2002

55

0

0

0

2500

71

698

503

0

56

6241

91

2003

15

0

0

1

4050

68

325

295

0

62

5500

149

2004

34

0

0

9

2867

78

2428

65

0

62

14834

159

2005

10

0

0

3

2908

60

511

288

0

87

12153

161

Y89/95

0

0

0

2

4083

740

874

100

0

64

4394

46

Y96/05

38

0

0

2

2089

92

2738

268

0

121

5553

371

Y00/05

20

0

0

2

2087

75

1853

268

0

112

7247

311

In Turkey, harvesting of sea snail is greatly increased for the recent two years. Analysis of fisheries along the eastern coast of Turkey (Samsun Province) showed that number of vessels using drags for sea snail harvesting in 2000 ? 2005 increased by large rates, especially in the vessel group 33 ? 149 Hp, typically boats that combine sea snail dredging, bottom trawling and net fıshing (Knudsen and Zengin, 2006). The small boat non-trawler engine power has increased at a much greater extent (468%), which are also used for sea snail harvesting. Although resources of this mollusk are still withstanding such high intensity of fisheries, large-scale implementation of drags has a destructive effect on bottom biocenosis and the ecosystem as a whole.

Until the early 1990s along the Ukrainian coast sea snail was harvested in an amateurish way for a fine shell used as souvenirs. The distribution and the stock assessment of sea snail in the Ukrainian territorial waters in the area from Takil Cape to Chauda Cape were undertaken in 1990, 1994 and 1999. Stocks of this mollusk were, respectively, assessed as 2.8 thousand tons, 1.5 thousand tons and 1.3 thousand tons. The former two assessments belonged to the initial commercial exploitation of this ground, the latter to the period of the intensive fisheries. Reduction in sea snail stocks from 1.5 ? 2.8 thousand tons (virgin population) to 1.3 thousand tons (exploited population) is the evidence of drag fisheries impact. The use of knife-edge drags adversely affected the bottom biocenoses.

In 1994 sea snail stocks were assessed along the southern and western coasts of the Crimea from Cape Ilya to the Cape Evpatoriisky as 14 thousand tons, and the limit for its harvesting in the waters of Ukraine begin to be established as 3 thousand tons. Maximum sea snail harvest reached the amount of 913 tons in 2000. After 2000 small-sized sea snail of 50-60 mm long was predominant in the catches from this ground. The causes of present rejuvenation of sea snail population was most probably overfishing, accompanied by the intensive harvesting of individuals of older ages (more than 75 mm long). Therefore since 2002, the annual limit for sea snail harvesting in the Ukrainian waters was reduced to 400 tons. After this limit, snail harvests reduced greatly. By mid-2000s, an increase in abundance and individual size of this mollusk was noted along the coast of the Crimea.

9.5.3. Сlams

Striped venus (Chamelea gallina L., 1758) is a small-sized bivalve mollusk, inhabiting sandy ground at depths up to 35 m. It maturates at the second year of life. It reproduces during the warm period of the year (July ? September); larvae are pelagic. Adult mollusk is a filtrator and seston-eater. Biocenoses of striped venus are characterized by abundant biomass. In northwestern Black Sea the largest abundance of clam is observed at 7 ? 8 m depth on sands and sandy-shells up to 600 ? 800 individuals/m2 and even higher in southern areas of the sea.

Among Black Sea countries Turkey is the only one to conduct regular striped venus harvesting. Dynamics of its harvesting is characterized by rapid growth for the first three years after beginning of harvesting and subsequent five-year period of decline (Fig. 9.20). In 1996 ?2005 increase in landings was observed; mean annual catches made up 9459 tons.

Due to its non-consumption within the country, it is exported to EU countries as frozen or canned food. According to Dalgı? and Okumuş (2006), the hydraulic dredge boats operated in clams fishing was 39 in 2006, the majority of which were concentrated along the southwestern coast of the Black Sea. Fishing season begins with 1st of September and ends at 30th of April. Pressure on different sites of the coast is regulated by means of their opening or closure from season to season. Its sustainable production requires standardizing the sieves, freezing the fishing license of striped venus, putting quotas and sharing out the fishing grounds between the boats.

?

Fig. 9.20. Harvesting of striped venus in the Black Sea along the Turkish coasts.

9.6. Water plants

Water plants have commercial value only in the Ukrainian sector of the Black Sea. They are red algae, represented mainly by species Phyllophora? nervoza, one species of brown algae (Cystoseira barbata), and eel-grass (Zostera marina). The share of water plants in the regional value of MLR capture was never high, and for the last 10 years after ceasing red algae capture it became insignificant. (Fig. 9.21).

In the Black Sea, Ukraine is the only country conducting harvesting red algae (Phyllophora nervosa, Ph. brodia) and sea grass (Zostera spp.). For the last 10 years, their harvesting had no regular character and no significant commercial value. Phyllophora harvesting ceased after 1996. The primary cause was economic problems that resulted in bankruptcy and suspension of plant for phyllophora processing and agar production (Odessa). The second cause was the rise in the cost of production due to the reduced productivity of phyllophora harvesting. In 1960s, the area of phyllophora field occupied about 12 thousand km2 with total biomass of 9 million tons (Kaminer, 1971). Since the early 1970s with the deterioration of environmental conditions in the northwestern Black Sea, the size of this unique biocenosis and stock began to reduce quickly. In the mid-1980s, the area of its settlements reduced to 4 thousand km2 and the total biomass to 0.3 million tons (Zaitsev, 1989). Reduction in phyllophora field likely took place as a combination of increased chemical pollution of the marine environment and eutrophication, reduced transparency including lifting of mud particles in the water column during bottom trawling, hypoxia and subsequent mass mortalities.

?

Fig. 9.21. Total capture production of main water plants in the Black Sea in 1989 -2005.

According to the data from the YugNIRO?s survey in 2000, the area of the northwestern part of the sea was covered by 1.5 thousand square kilometers that was the densest commercial phyllophora aggregations observed during the last years. Its stock was assessed to be around 8 thousand tons which used to be 121 thousand tons in 1993.

9.7. Conclusions

Historically, the main factors leading to stock collapses and great losses in fisheries were eutrophication-induced changes in the food web, overfishing and the invasion of the comb-jelly M. leidyi. In the recent period 2000-2005, the major threat for the fish resources appear to be the illegal fishing and the use of destructive harvest techniques as well as the lack of regional cooperative management of fisheries and eutrophication. At present, no recovery of the spawning and nursery habitat for sturgeons took place in rivers and lagoons. The amounts of restocking of the Dnieper sturgeon populations reduced considerably and the state of sturgeon stocks after 1999 deteriorated definitely with collapse not being excluded. The state of Danube shad stocks did not improve; nevertheless the situation is less disastrous as compared to sturgeons. The sprat, anchovy, picked dogfish, and mullet stocks partially recovered in 1995 ? 2005, but the current level of relatively high fishing efforts and catches impose a risk of deterioration of their stocks. On the other hand, the horse mackerel stock continues to be in a depressed state with low stock size and there is no sign of its recovery. The whiting and turbot stocks are exploited rather intensively and declining. In 2000 ?2005, mussel catch had a negative trend in the Ukrainian sector but as a whole the state of mussels improved in the Black Sea. The total state of water plant resources continues to be in deteriorated state.

The summary table describing the current status of MLRs with respect to the previous phases (Table 9.13) in general suggests an improvement in the state of MLR during 2000 ? 2005 with respect to the collapse period (1989 ? 1992) but the overall situation is still inferior when compared with the baseline state (1970 ? 1988). The highly variable stock dynamics and the lack of effective control measures for the fisheries quite likely may lead to sharp stock declines in the future. In order to avoid this risk and to achieve sustainable development of fisheries in the Black Sea, implementation of a regional fisheries management strategy is necessary.


Table 9.13. Indicators for the fisheries in the Black Sea for 1970 ? 2005 (Caddy?s method) .

Category/

Species

Baseline

(1970-1988)

?Collapse years?

(1989-1992)

?Post-collapse? years (1993-2005)

Present decade

(2000 - 2005)

Trend

Average

tons/year

Trend

Average

tons/year

Trend

Trend

Average

tons/year

Landings as % of baseline

Landings as % of ?collapse years?

+

-

0

280757

214%

+

-

0

13323

27%

+

-

+

60537

123%

+

-

+

10120

156%

0

+

+

16137

174%

-

-

-

1250

120%

+

-

-

9091

45%

+

-

-

1132

31%

-

+

-

1770

148%

0

+

-

6538

236%

N/A

-

+

9832

166%

Ratio (trends)

?+ve/-ve

3/7

=2.00

=0.38

=0,80


References

Acara A. (1985) The Black Sea turbot. State Planning Organization, Ankara, Turkey.

Ambroz A. M., Kirilluk M. M. (1979) Sturgeons (in Russian). In: ?Fisheries resources of the Black Sea?, Tkacheva K. S. and Yu. K. Benko (eds). USSR, Moscow: Pishchevaja Promyshlennost, 242-247 (in Russian).

Anon. (1997) Black Sea transboundary diagnostic analysis. UNDP, New York, 142pp.

Arkhipov A. G. (1993) Estimation of abundance and peculiarities of distribution of the commercial fishes in the early ontogeny. Journal of Ichthyology, USSR, 33 (4), 511-522 (in Russian).

Bingel F., G?g? A. C., Stepnovski A., Niermann U., Mutlu E., Avşar D., Kideyş A. E., Uysal Z., İşmen A., Gen? Y., Okur H., Zengin M. (1996) Stock assessment study for Turkish Black Sea cost. METU IMS Erdemli and FRI Trabzon, T?BİTAK, Final Report, 159pp.

Bryantsev V. A., Serobaba I. I., Shlyakhov V. A., Yakovlev V. N. (1994) Biological resources of the Black Sea in the present ecological conditions,? Proceeding of the Black Sea Symposium Ecological Problems and Economical Prospects (Ed. K. C. Guven). Istanbul, Acar Matbaacilik A.S, 293-296.

Caddy J.F. (2006) The potential use of indicators, reference points and the traffic lights convention for managing Black Sea fisheries. In: Selected papers presented at the Workshop on biological reference points , 20-21 April 2004. G. Lembo (Ed.). Studies and Reviews. GFCM. 83, 1-24.

Chashchin A. K. (1998) The anchovy and other pelagic fish stock transformations in the Azov-Black Sea basin under environmental and fisheries impact. The proceedings of the First International Symposium on Fisheries and Ecology, 1-10.

Dalgı? G., Okumuş İ. (2006) Clam fisheries with hydraulic dredges in the Black Sea. 1st Bilateral Scientific Conference ?Black Sea Ecosystem 2005 and Beyond? 8-10 May 2006, Istanbul, Turkey.

Daskalov G. (1998) P?cheries et changement environmental ? long-term en mer Noire. PhD thesis. Centre d?oc?anologie de Marseille, Univ. Aix-Marseille II (in French).

Daskalov G. (1999) Relating fish recruitment to stock biomass and physical environment in the Black Sea using generalised additive models. Fish Res., 41, 1-23.

Daskalov G. M. (2002) Overfishing drives a trophic cascade in the Black Sea. Mar Ecol Prog Ser., 225, 53-63.

Daskalov G. M. (2003) Long-term changes in fish abundance and environmental indices in the Black Sea. Mar. Ecol. Prog. Ser., 255, 259-270.

Daskalov, G. and Prodanov, K. (1994) Variability in growth of sprat Sprattus sprattus L. off Bulgarian Black Sea coast with reference to the environmental changes in the sea.. In: Proceedings of the International Conference with a Workshop on regional cooperation project for integrated research and -monitoring of the Black Sea (Black Sea'94), 12 - 17 Sep. 1994, Varna, 81-85.

Daskalov G., Prodanov K. Shlyakhov A. and K. Maxim (1996) Stock assessment of sprat Sprattus sprattus L. in the Black Sea during 1945-1993 using international fishery and research data. Izv.IRR, Varna, 24, 67-93.

Daskalov, G. M., Prodanov, K. and Zengin, M. (2007) The Black Seas fisheries and ecosystem change: discriminating between natural variability and human-related effects. In: Proceedings of the Fourth World Fisheries Congress: Reconciling Fisheries with Conservation (ed? J. Nielsen, J. Dodson, K. Friedland, T. Hamon, N. Hughes, J. Musick and E. Verspoor). American Fisheries Society Symposium 49, 587?602.

Duzgunes E. (2006) TDA TTT National Report Turkey. UNDP/GEF Black Sea Ecosystem Recovery Project Phase II, 29 pp.

FAO Fisheries Department, Fishery Information, Data and Statistics Unit. FISHSTAT Plus: Universal software for fishery statistics time series. Version 2.3. 2000 ? 2005. FAO, 2007.

Fashchuk D.Ya., Samyshev E.Z., Sebakh L.K., Shlyakhov V.A. (1991) Forms of anthropogenic impact on the Black Sea ecosystem and its state under modern conditions. J. Ecology of the sea, 38, Ukraine, Kiev: Naukova dumka, 19-28 (in Russian).

Gen? Y., Mutlu C., Zengın M., Aynın İ., Zengın B., Tabak İ. (2002) Doğu Karadeniz?deki Av G?c?n?n Demersal Balık Stokları ?zerine Ektisinim Tesbiti. Tarım K?yişleri Bakanlıgi, TAGEM, Trabzon Su ?r?leri Mekez Araştırma Enstit?s?, Sonu? Raporu Proje No: TAGEM/IY/97/17/03/006, ss:114 (in Turkish).

Grishin A. N. (1994) Dietary daily regime and food spectrum of ctenophore M. leidyi in the conditions of the Black Sea. In: Proceedings of the Southern Scientific Research Institute of Marine Fisheries &. Oceanography, 40, 45-47 (in Russian).

Grishin A., Daskalov G., Shlyakhov V., Mihneva V. (2007) Influence of gelatinous zooplankton on fish stocs in the Black Sea: analysis of biological time-series. Marine Ecological Journal, 6(2), Sevastopol, 5-24.

Gucu, A. C. (1997) Role of fishing in the Black Sea ecosystem. Pages 149-162 in E., ?zsoy, and A., Mikaelyan, editors. Sensitivity to change: Black Sea, Baltic Sea and North sea. NATO ASI Series, 2. Environment, vol. 27. Kluwer Academic Publishers, Dordrecht, Netherlands.

Ivanov L. and Beverton R.J.H. (1985) The fisheries resources of the Mediterranean. Part two: Black Sea. FAO studies and reviews, 60, 135.

İşmen A. (2003) The whiting (Merlangius merlangus euxinus L.) in the Turkish Black Sea coast. In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey, 27-34.

Kaminer K. M. (1971) Distribution and stocks of Phyllophora in the northwestern Black Sea according to the data of survey in 1969. In: Prospects of development of fisheries in the Black Sea. USSR, Odessa, 108-109 (in Russian).

Kirnosova I. P. (1990) Growth parameters and mortality of spiny dogfish from the Black Sea. In: Biological resources of the Black Sea. Collected papers. USSR, Moscow: VNIRO, 113-123 (in Russian).

Kirnosova I. P., Lushnicova V. P. (1990) Feeding and food requirements of spiny dogfish (Squalus acanthias L.). ? Biological resources of the Black Sea. Collected papers. USSR, Moscow: VNIRO, 45-57 (in Russian).

Knowler D. (2005) Reassessing the costs of biological invasion: Mnemiopsis leidyi in the Black sea. Ecological Economics, 52, 187? 199.

Komakhidze A., Diasamidze R., Guchmanidze A. (2003) State of the Georgian Black Sea demersal ichthioresources and strategy for their rehabilitation and management. In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey, 93 ? 103.

Knudsen S. and Zengin M. (2006) Multidisciplinary modeling of Black Sea fisheries: a case study of trawl and sea snail fisheries in Samsun. 1 st Bilateral Scientific Conference ?Black Sea Ecosystem 2005 and Beyond? 8-10 May 2006, Istanbul, Turkey.

Lipskaya N. Ya., Luchinskaya T.N. (1990) Biology of ctenophore M. leidyi. Journal Rybnoye Khozyaystvo, 9, 36-38 (in Russian).

Maklakova I.P., Taranenko N.F. (1974) Some information on biology and distribution of picked dogfish and Raja rays in the Black Sea and recommendations for their fisheries. USSR, Moscow: VNIRO Proceedings, 104, 27-37 (in Russian).

Maximov V., Nicolaev S., Staicu I., Radu G.,Anton E., Radu E. (2006)? Contributions a la connaissance des caraceristiques certaines especes de poisons demersaux de la zone marine roumane de la mer Noire. Cercetari marine I.N.C.D.M. 36, 271-297 (in French).

Mikhajlyuk, A.N. (1985) Factors determining the abundance of young Black sea scad. In: Oceanographic and fisheries investigations of the Black Sea, Coll. reprints of VNIRO, Moskow, 81-86 (In Russian).

Mikhailov, K. and Prodanov, K. (2002) Early sex maturation of the anchovy Engraulis encrasicolus (L.) in the northwestern part of the Black Sea. Page 34 in National Centre for Marine Research, Athens (Greece), 3rd EuroGOOS Conference: Building the European capacity in operational oceanography.

Navodaru I., Staraş M., Banks R. (1999) Management of sturgeon stocks of the lower Danube River system. In: ?The Delta?s: State-of-the-art protection and management?, Romulus Stiuca and Iulian Nuchersu (eds). Conference Proceedings, Tulcea, Romania, 26-31 July 1999, 229-237.

Nicolaev S., Maximov V., Anton E. (2003) Actual state of Romanian marine demersal fisheries In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey , 104 ? 114.

?zdamar E., Samsun O., Kihara K. and Sakuramoto K. (1996) Stock assessment of whiting, MERLANGIUS MERLANGUS EUXINUS along the Turkish coast of the Black sea. Journal of Tokyo University of Fisheries, v. 82 (2), 135-149.

Panayotova M., Todorova, V., Konsulova, Ts., Raykov, V., Yankova, M., Petrova,? E., Stoykov, S. (2006) Species composition, distribution and stocks of demersal fishes along the Bulgarian Black Sea coast in 2006. Technical report.

Panov, B. N. and Spiridonova, E. O. (1998) Hydrometeorological prerequisites for formation of fishable concentrations and migration of the Black Sea anchovy in the south-eastern part of the Black Sea. Oceanology, Moskow, 38, 573-584 (in Russian).

Pirogovskiĭ M. I., Sokolov L. I. & Vasil?ev V. P. (1989) Huso huso (Linnaeus, 1758). ? In: The Freshwater Fishes of Europe Vol. 1, Part II General Introduction to Fishes/Acipenseriformes, Holčic (Ed.). AULA-Verlag, Weisbaden, 469pp.

Popova V. P. (1967) Methods of evaluation of the state of the turbot stocks in the Black Sea. ? USSR, Moscow: Proc. VNIRO, 62, 197 ? 204 (in Russian).

Popova A. A., Shubina T. N. & Vasil?ev V. P. (1989) Acipenser stellatus Palllas, 1771. ? In: The Freshwater Fishes of Europe Vol. 1, Part II General Introduction to Fishes/Acipenseriformes, Holčic (Ed.). AULA-Verlag, Weisbaden, 469pp.

Prodanov K, Bradova, N. (2003) Stock Assessment of the Whiting (Merlangius merlangus) in the Western Part of the Black Sea During 1971-1997. Proc. Institute of Oceanology, 4, 149-156.

Prodanov K., Mikhailov, K. (2003) Possibilities for Applying the Jones Methods for Turbot Stocs Assessment and Catch Projection in the Black Sea. In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey, 35 ? 48.

Prodanov K., Mikhailov K., Daskalov G. M., Maxim K., Chashchin A., Arkhipov A., Shlyakhov V.,? Ozdamar E. (1997) Environmental management of fish resources in the Black Sea and their rational exploitation. Studies and Reviews. GFCM. 68, FAO, Rome,? 178pp.

Prodanov K. and Konsulova, (1993) Stock assessment of Sea snail. Rapana thomasiana in front the Bulgarian Black seacoast. IO-BAS Proceedings (in Bulgarian).

Radu G. (2006) The state of main habitats important for Black Sea marine living resources. Romanian second Fishery Report. UNDP/GEF Black Sea Ecosystem Recovery Project Phase II, 29 pp.

Radu G., Nicolaev S., Radu E., Anton E. (2006) Evolution of main indicators of marine living resources from the Romanian Black Sea sector in 2004 and 2005. 1 st Bilateral Scientific Conference ?Black Sea Ecosystem 2005 and Beyond? 8-10 May 2006, Istanbul, Turkey.

Raykov V. (2006) TDA TTT National Fishery Report (first) Bulgaria. UNDP/GEF Black Sea Ecosystem Recovery Project Phase II, 4 pp.

Raykov V. , Schlyakhov Vl , Maximov ,V. , Radu, Gh. , Staicu, I. , Panayotova, M , Yankova, M , Bikarska I. 2008. Limit and target reference points for rational exploitation of the turbot (Psetta maxima L.) and whiting (Merlangius merlangus euxinus Nordm.) in the western part of the Black Sea.Acta Zoologica Bulgarica, Suppl.2, 305-316.

Reinartz R. (2002) Sturgeons in the Danube River, Biology, Status, Conservations. (Literature study). International Association for Danube Research (IAD). Bezirk Oberpfalz, Landesfischereiverband Baern. 150 pp.

Revina N. I. (1964) Biological research of the Black Sea and its fishing resources. On provision of anchovy and horse mackerel larvae with feed in the Black Sea. Proceedings of AzCherNIRO, Kerch, 23, 105-114 (in Russian).

Serobaba I.I., Domashenko G.P., Yuriev G.S., Malyshev I.I., Gapishko A.I., Shlykhov V.A., Kirillyuk M.M., Kaminer K.M., Domashenko Yu.G., Vinarik T.V., Timoshek N.G., Kirnosova I.P., Mikhailyuk A.N., Korkosh N.I., Akselev O.I., Chashchin A.K., Zhigunenko A.V., Litvinenko N.M. (1988) Commerical Fishery Description of the Black Sea (section: "Characteristics of the commercial species", "Description of fishing grounds"). AzcherNIRO, Publishing House of the Chief Department of Navigation and Oceanography of the Ministry of Defense for the Ministry of Fisheries of the USSR, 48-96 (in Russian).

Shlyakhov V. A. (1983) Biology, distribution and fishery of whiting (Odontogadus merlangus euxinus (Nordmann) in the Black Sea. USSR, Moscow, Proceedings of VNIRO "Biological resources and prospects of fishery of new species ? fishes and invertebrates", 104-125 (in Russian).

Shlyakhov V. A. (1994) Estimation of Dnieper sturgeon population abundance in the North-Western Black Sea? In: The main results of YugNIRO complex researches in the Azov-Black Sea Basin and the World Ocean in 1993. Ukraine, Kerch: YugNIRO, 40, 50-55 (in Russian).

Shlyakhov, V. (2003) Management of Fisheries and Other Living Marine Resources, National Report and Data Sheets in Ukraine. Workshop on Responsible Fisheries in the Black Sea and the Azov Sea, and Case of Demersal Fish Resources, April 15-17 2003, Şile, İstanbul, BSEP Programme, Country Report, T?DAV/BSEP/ UNDP/GEF. 11 pp.

Shlyakhov V. A., Akselev O. I. (1993) Stock?s state and reproduction efficiency of Russian sturgeon in the Black Sea Norht-Western part. Ukraine, Kerch, Proc. YugNIRO, 39, 78 ? 84 (in Russian).

Shlyakhov, V., Charova, I. (2003) The Status of the Demersal Fish Population along the Black Sea Cost of? Ukraine. In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey, 65 ? 74.

Shlyakhov, V., Charova, I. (2006) Scientific data on the state of the fisheries resources of Ukraine in the Black Sea in 1992 ? 2005. 1 st Bilateral Scientific Conference ?Black Sea Ecosystem 2005 and Beyond? 8-10 May 2006, Istanbul, Turkey, 131-134.

Shlyakhov V.A., Chashchin A.K., Korkosh N.I. (1990) Intensity of fisheries and dynamics of the Black Sea anchovy stocks. In: Biological resources of the Black Sea, USSR, Moscow: VNIRO, 93-102 (in Russian).

Shlyakhov V.A., Goubanov E.P., Demyanenko K.V. (2005) On state of stocks and unreported catches of Azov sturgeons. In: Materials of the scientific practical Conference ?Problems and solutions of the modern fisheries in the Azov Sea basin?, Izergin L.V. (Ed.), Ukraine, Mariupol: Publishing House ?Renata?, 59 ? 61 (in Russian).

Shul'man, GE; Chashchin, AK; Minyuk, GS; Shchepkin, VYa; Nikol'skij, VN; Dobrovolov, IS; Dobrovolova, SG; Zhigunenko, A.S. (1994) Long-term monitoring of the Black Sea sprat condition. DOKL. RAN, Moscow, 335(1), 124-126.

Shushkina E. A., Musaeva E. I. (1990) Structure of the plankton communities in the epipelagic zone of the Black Sea. Oceanology, 30(2), 306-310 (in Russian).

Simonov AI, Ryabinin AI, Gershanovitch DE (eds 1992). Project ?The USSR seas?. Hydrometheorology and hydrochemistry of the USSR seas. Vol. 4: Black Sea, no. 1: Hydrometheorological conditions and oceanological bases of the biological productivity. Hydrometheoizdat, Sankt Peterbourg (in Russian).

Sorokin Yu.I. (1982) The Black Sea: Nature, resources. USSR, Moscow: Nauka, 216pp (in Russian).

Svetovidov A. N. (1964) The Black Sea fish. Moscow-Leningrad: USSR, Moscow:Nauka,? 546 pp (in Russian).

Tkatcheva KS, Benko YuK (eds) (1979). Resources and raw materials in the Black Sea, AzTcherNIRO, USSR, Moscow: Pishtchevaya promishlenist, 323 pp (in Russian).

Toje H. and Knudsen S. (2006)? Post-Soviet transformations in Russian and Ukrainian Black Sea fisheries: socio-economic dynamics and property relations. 1 st Bilateral Scientific Conference ?Black Sea Ecosystem 2005 and Beyond?, 8-10 May 2006, Istanbul, Turkey.

Tonay A. M., ?zt?rk B. (2003) Cetacean Bycatch ? Turbut fisheries interaction in the western Black Sea. In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey, 1-8.

Tsikhon-Lukonina E.A., Reznichenko O.G., Lukasheva T.A. (1991) Quantitative regularities in the diet of the Black Sea ctenophore M. leidiy. Oceanology, 31(2), 272-276 (in Russian).

?Vlasenko A. D., Pavlov A. V. & Vasil?ev V. P. (1989) Acipenser gueldenstaeti Brant, 1833. ? In: The Freshwater Fishes of Europe Vol. 1, Part II General Introduction to Fishes/Acipenseriformes, Holčic (Ed.). AULA-Verlag Weisbaden, 469pp.

Vinogradov M. E., Shushkina E. A., Nikolaeva G. G. (1993) State of zoocenoses in the open areas of the Black Sea in late summer 1992. Oceanology, 33(3), 382-387 (in Russian).

Volovik S. P., Agapov S. A. (2003) Composition, state and stocks of the demersal fish community of the Azov-Black Seas relating to the development of Russian sustainable fisheries. In: Workshop on Demersal Resources in the Black & Azov Sea, B. ?ztűk and S. Karakulak (Eds.). Published by Turkish Marine Research Foundation, Istanbul, Turkey, 82-92.

Zaitsev Yu. P. (1989) ? The state and tendency of development of the Black Sea ecosystem. In: Southern Seas of the USSR: Geographical problems of research and exploration. Leningrad: Geographical Society of the USSR, 59-71.

Zaitsev Yu. P. (1992) The ecological state of the shelf zone of the Black Sea near Ukrainian costs. Journal of Hydrobiology, 28 (4), 3-18 (in Russian).

Zengin M. (2000) T?rkiye?nin Doğu Karadeniz Kıyılarındaki Kalkan (Scopthalmus maeoticus) Balığının Biyoekolojik? ?zelikleri ve Populasyon Parametleri, Doktora Tezi, KT? Fen Bilimleri Estit?s?, Balık?ılık Teknolojisi M?hendisliği Anabilim Dalı, 225pp (in Turkish).

Zengin, M. (2003) The Current Status of Turkey's Black Sea Fisheries and Suggestions on the Use of Those Fisheries, Workshop on Responsible Fisheries in the Black Sea and the Azov Sea, and Case of Demersal Fish Resources, April 15-17 2003, Şile, Istanbul, BSEP Black Sea Environmental Programme Country Report, 34pp.

Zolotarev P. N., Shlyakhov V. A., Akselev O. I (1996) The food supply and feeding of Russian sturgeon Acipenser gueldenstaedti and the starred stuggeon A. stellatus on the Nordwestern part of the Black Sea under modern ecological conditions. Journal of Ichthyology, 36(4), 317?322 (in Russian).