Habitat and Biology
Climatic zone: Temperate.
Water Area Overview
The Mediterranean and Black Seas (Figure B5.1) are semi-enclosed seas with a surface of about 3.3 million km2
, which represents 0.8 percent of the total world marine surface. These seas are located within a relatively narrow range of latitudes (from 30°N to 46°N) in the temperate zone of the Northern Hemisphere.
The continental shelf throughout Area 37 is mostly a narrow coastal fringe with the exceptions of the Adriatic Sea, Gulf of Gabès, northern Black Sea, south of Sicily, Gulf of Lions and the Nile Delta and represents only 23 percent of the total area. The Mediterranean Sea water masses are stratified in summer, but the temperature of the water masses below 400 m is very stable at 13 ± 0.3 °C throughout the year. The Mediterranean has a negative water budget – the loss of water through evaporation is greater than the inputs from rain and river runoff. Hence, the contribution of about 1 700 km3/year of Atlantic water through the Strait of Gibraltar balances these losses (Bas Peired, 2005). The Mediterranean is globally considered as an oligotrophic sea (Margalef, 1985), and the gradual decline in nutrient content as the water moves from west to east leads to an overall reduction in productivity. Despite this, there are local exceptions owing to incoming nutrients from rivers and from the Black Sea.
The continental shelves of the Black Sea are widest in the northwest and southwest regions, and do not exceed 20 km in the remaining parts of the sea. The Black Sea is linked to the Mediterranean through the Turkish Straits System (the Bosphorus, Dardanelles Straits and the Sea of Marmara). Europe’s second, third and fourth rivers (the Danube, Dnieper and Don Rivers) all flow to the Black Sea, pouring 350 km3/year of river water into the Black Sea. This large amount of freshwater tends to stay at the surface, mixing little with the remaining water of the sea and causing a very marked stratification of the water column. Only the top 10 percent of the Black Sea is able to support aerobic organisms. The water mass below 150–200 m is devoid of dissolved oxygen and contaminated with hydrogen sulphide. The Black Sea has a positive water balance, and the outflow through the upper layer of the Bosphorus (612 km3/year) is about twice as large as the inflow (312 km3/year), that comes through the bottom (Ünlüata et al., 1990).
The Azov Sea in the northwest part of the Black Sea is the shallowest sea in the world with an average depth of 7 m. Because of the large inflow of freshwater, it has a comparatively low salinity (about 10–12 psu) in the open sea. Salinity is reduced even further in the inner areas to the east of the sea where it is almost freshwater.
|Figure B5.1 The Mediterranean and Black Seas (Area 37) |
Considered a single stock: No
Introductions of exotic species have caused and are causing major changes in the Mediterranean and Black Sea regions. In the Black Sea, drastic ecological changes have led to the collapse of the major anchovy fishery. These major changes have occurred following the introduction of a number of harmful exotic phytoplankton and animals that were carried in ship ballast water or attached to ship hulls. The one introduction that has had the most visible impact on fisheries has been the introduction of the ctenophore Mnemiopsis leidyi
. In the Mediterranean, the most noteworthy of these effects is the progressive invasion of the eastern Mediterranean by a growing number of Red Sea species entering the eastern Mediterranean through the Suez Canal (Lessepsian migrants). These species now dominate the fisheries in some of the eastern Mediterranean countries, and are also likely to become important in other parts of the Mediterranean (EastMed, 2011). Even though some of the new species are highly valuable fishery targets and are welcome by fishers, others, like Lagocephalus sceleratus
, create major problems to the fisheries in the region. This latter species damages most nets and is also highly poisonous (EastMed, 2011). The dramatic accidental introduction and spread of a species of seaweed (Caulerpa taxifolia
) into the western Mediterranean will also probably affect demersal food chains in that region in a way that is not easily predicted (Zaitsev and Öztürk, 2001; Galil, Froglia and Noël, 2002; Golani et al., 2002).
Mediterranean fisheries are dominated by small-scale vessels, dispersed across a large number of landing places in most countries. Four main types of fisheries can be identified:
(i) the industrial fishery for large pelagic fish, such as tunas and swordfish,that is carried out by a number of highly sophisticated and powerful vessels using purse seines and longlines;
(ii) a fishery for small pelagic fish, targeting mostly anchovy, sardine and sprat, undertaken mostly by small to medium-sized purse seiners and pelagic trawlers;
(iii) a multispecies demersal fishery, carried out by a multitude of small to medium-sized vessels that use a variety of gear types including trammel nets, gillnets, traps, pots, handlines, longlines and bottom trawls; and
(iv) a fishery for deepsea crustaceans (mostly deep-sea shrimps and Norway lobster) and fish (mostly hake), with a fleet of small to medium-sized bottom trawlers.
Small pelagic fish, mostly European anchovy (Engraulis encrasicolus
), European pilchard (Sardina pilchardus
), and sprat (European sprat [Sprattus sprattus
] and Black and Caspian sea sprat [Clupeonella cultriventris
]) make up 50–60 percent of total declared catch. The species classified as demersal represent about 30 percent of total reported catches in the Mediterranean and Black Sea. The most important of these are hake (Merluccius merluccius
), red mullets (Mullus
spp.), blue whiting (Micromesistius poutassou
), whiting (Merlangius merlangus
), anglerfishes (Lophius
spp.), pandoras (Pagellus
spp.), bogue (Boops boops
), picarels (Spicara
spp.) striped venus (Chamelea gallina
), octopus (Octopus
spp.), cuttlefish (Sepia officinalis
), red shrimps (Aristeus antennatus
and Aristaeomorpha foliacea
), Norway lobster (Nephrops norvegicus
) and deep-water rose shrimp (Parapenaeus longirostris
). Profile of catches
Total declared catches in Area 37 showed a steady increase from about 0.7 million tonnes in 1950 to about 2 million tonnes in the period 1982–88 (Figure B5.2; Table D5
They then suddenly declined to about 1.3 million tonnes following the collapse of the Black Sea fishery for sprat and anchovy (Figure B5.3), and have since recovered slightly to about 1.5 million tonnes. Total nominal catches have been fluctuating around this level since 1992.
The declared catches of species other than small pelagics increased steadily until they reached a maximum of about 700 000 tonnes in the mid-1980s. Since then, catches have declined, but with some fluctuations. The decline in catches in the last five years is a general feature for these species. The small pelagic fish show a different pattern, dominated by events in the Black Sea (Figure B5.3). After a sharp increase from 700 000 tonnes to 1.3 million tonnes in six years, they fluctuated around this level from 1983 to 1988 then fell sharply to less than 620 000 tonnes in 1991. They recovered to more than 950 000 tonnes in 1995 and have fluctuated between 800 000 and 1 million tonnes since 1999.
Among small pelagic fish, anchovy (Engraulis encrasicolus
) are the most important species landed, with about 50 percent of total, followed by sardine (Sardina pilchardus
), with about 25 percent. The other important small pelagic fish species caught in the region are European sprat (Sprattus sprattus
), Black and Caspian Sea sprat (Clupeonella cultrivensis
, especially important in the Azov Sea), jack and horse mackerels (Trachurus
spp.), sardinella (Sardinella aurita
)and chub mackerel (Scomber japonicus
|Figure B5.2 Total annual nominal catches from the Mediterranean and Black Seas from 1950 to 2009, grouped by major ISSCAAP groups |
|Figure B5.3 Annual nominal catches of selected species in ISSCAAP Groups 24 and 35 |
The large increase in catches of European anchovy until the mid-1980s was probably mainly due to the steady increase in fishing effort. However, it may also have been partly a response to the increasing eutrophication of the Black Sea in this period (Ludwig et al., 2009). The collapse of the small pelagic fish fisheries in the Black Sea around 1990 has been linked to the outbreak of the ctenophore Mnemiopsis leidyi
(Oguz, Fach and Salihoglu, 2008) as it added to the existing heavy fishing pressure. These fisheries have subsequently recovered, but catches have not reached the levels of the 1980s. This may be partly due to the decrease in nutrient input that was a result of both the successful control of fertilizer runoff by the riverine nations and the profound economic changes in the river catchments (Ludwig et al., 2009). Nominal catches of jack and horse mackerels show a pattern similar to other species in the region (Figure B5.4). The catches fluctuated around 50 000 tonnes until 1975, when catches increased rapidly until they reached 200 000 tonnes in 1985, before then declining equally rapidly to the previous level. Reported catches of grey mullets (Mugillidae) tripled from 1988 to 2000, only to return to close to the previous values by 2008 (Figure B5.5). However, those of silversides (Atherinidae) have been relatively stable, despite a temporary increase between 1985 and 1995. The nominal catches of dolphinfish (Coryphaena hippurus
) have always been at very low levels, but started increasing appreciably at the beginning of the 2000s and are currently at the highest level recorded. This increasing trend in catch has probably mainly been the result of increased fishing effort by some countries sharing the stock. The declared catches of most demersal and semi-pelagic fish and crustaceans increased steadily until the period between the 1980s and the end of the 1990s. This has been followed by declines in several species in the last few years.
|Figure B5.4 Annual nominal catches of selected species in ISSCAAP Group 37 |
|Figure B5.5 Annual nominal catches of selected species in ISSCAAP Groups 33 and 37 |
One of the main target species in the Mediterranean is European hake (Merluccius merluccius
). Nominal catches of European hake increased steadily until the mid-1990s. However, after reaching their maximum (52 000 tonnes), they declined abruptly, to levels that were less than half of the maximum (about 21 000 tonnes) by 2003. Catches later recovered to levels close to those recorded in the early 1980s (Figure B5.6). Nominal catches of red and striped mullets (Mullus barbatus
and M. surmuletus
) increased regularly from the 1950s until the mid-1990s. Their catches showed a small decline in the following decade before recovering to close to the maximum. The fishery begins on age group 0, and in many regions the small individuals (caught mostly in summer and early autumn) are considered a delicacy, fetching higher prices than the adults (Tserpes et al., 2002; Bas Peired, 2005).
|Figure B5.6 Annual nominal catches of selected species in ISSCAAP Groups 32 and 33 |
Sparids and seabreams are heavily exploited across the whole region (Bas Peired, 2005). Their catches have shown a similar pattern to that of other demersal species. There was a regular increase until the mid-1990s, followed by a marked fall the following decade, and a partial recovery in the last 5–8 years (Figure B5.7).
|Figure B5.7 Annual nominal catches of selected species in ISSCAAP Group 33 |
Cephalopods are important catches from trawl fisheries and there are also directed fisheries in some regions especially with smaller vessels (Bas Peired, 2005). Catches of octopus and squid (Figure B5.8) reached a maximum at the end of the 1980s, followed by a more or less steady decline until 2009. The catches of cuttlefish, however, show a different pattern as they have been about 10 000 tonnes/year since the peak of the late 1980s.
|Figure B5.8 Annual nominal catches of selected species in ISSCAAP Group 57 |
The onset of deep-water trawling off the slope areas of the Mediterranean in the mid-1980s appears to explain the sharp rise in catches of deep-water rose shrimp and aristaeidae shrimp (Figure B5.9). The decrease in catches of rose shrimp observed in the mid-1990s is most probably the result of overexploitation of the main fishing grounds (GFCM, 2011a).
Its recovery in the last three years is probably associated with a period of good recruitment. The declared catches of Norway lobster follow a similar pattern, albeit less pronounced.
|Figure B5.9 Annual nominal catches of selected species in ISSCAAP Groups 43 and 45 |
The main large pelagic fishes commercially exploited in the Mediterranean, bluefin tuna (Thunnus thynnus
) and swordfish (Xiphias gladius
), are accompanied by albacore (Thunnus alalunga
) and Atlantic bonito (Sarda sarda
). Although they represent only about 4 percent of total catches, their economic value is far greater. These tuna and tuna-like stocks, whose distribution extends beyond the Mediterranean, are dealt with in detail in Chapter C1: World oceans Global Tuna fisheries
Nominal catches of bluefin tuna increased from the mid-1960s to reach almost 40 000 tonnes in the mid-1990s. They then dropped to below 25 000 tonnes and fluctuated around that level until 2008, when they dropped again to below 15 000 tonnes (Figure B5.10). It is possible that these declared catches do not include all those caught, especially in the last decade. This is because of the marked expansion of the farming of wild-caught fishes that are reported as part of aquaculture production instead.
|Figure B5.10 Annual nominal catches of selected species in ISSCAAP Group 36 |
The knowledge base for the assessments has also been improving. There is an increasing recognition that many if not most of the Mediterranean and Black Sea fish stocks tend to be at least partially shared among neighbouring countries. In this context, it is easily accepted that it has been beneficial to have the assessments undertaken jointly, either at the GFCM Stock Assessment Working Groups or at subregional Working Groups. These activities are usually organized within the framework of the FAO regional projects. In 2010, at least six joint stock assessments were conducted with the support of the FAO Mediterranean projects (AdriaMed, CopeMed, EastMed and MedSudMed). These stock assessments included the stocks of rose shrimp in the Strait of Sicily, of Pagellus bogaraveo
in the Alboran Sea, and of sardine, anchovy, hake and sole in the Adriatic Sea. In the last few years, there have also been other important efforts to improve the quality of the stock assessments. These efforts include at least the following: (i) the compilation of a database of the main biological parameters (growth, maturation and mortality) of the more-intensively exploited species in the region to facilitate the carrying out of comparable assessments with consistent parameter sets; and (ii) the introduction of a more systematic quality control and documentation system for all stock assessments, in the framework of the GFCM’s SAC as well as the EU’s STECF.
Management unit: No
With the exception of large pelagics and some particular fisheries (striped venus in the Adriatic, or sturgeon fisheries), fishery management in the Mediterranean is not based on catch control via TACs and quotas. The exception is the management of national fisheries in the Black Sea by the Russian Federation. Instead, the management of Mediterranean fisheries is based on regulation of total fishing effort through limited licences and technical measures such as time and area closures, gear limitations and limited landed sizes. Most countries have some form of closed-access system, through a limitation on the number of licences issued, although this is not the case in all countries and in all fleet segments. In most parts of the Mediterranean, trawlers are not allowed to operate in coastal waters (at least down to depths of 50 m and/or a distance of 3 nautical miles from the coast). These restrictions have been made in order to protect the nursery areas of several commercial species. A review of the fisheries management measures applied in the Mediterranean can be found in Cacaud (2005).
Countries neighbouring the Mediterranean have all established territorial waters up to 12 nm from the coast. However, none has actually claimed an EEZ out to 200 nm (Cacaud, 2005). Therefore, most of the Mediterranean Sea is classified as the high seas.
This means that international waters are much closer to the coasts than in most other seas and oceans. This situation requires a higher level of cooperation among coastal States for the management of Mediterranean fisheries. In the Black Sea, on the other hand, all coastal countries have claimed the 200 nm EEZs. This means that most of the fishing is carried out within the national jurisdiction of bordering countries.
In the Mediterranean, the overall management of all fisheries is done in the framework of the GFCM. The fisheries of the countries that are members of the EU are managed according to the CFP of the EU. In most cases for the Mediterranean, this policy is harmonized with the GFCM policy. Non-EU countries define their own fisheries management measures, although most try to ensure they are compatible with GFCM regulations. The GFCM has had a very limited role in the regulation of fisheries in the Black Sea until recently. This is because not all countries bordering the Black Sea are members of this organization.
There are a number of major difficulties for adequate fisheries management in the region. These include: the overcapacity of the fleet, widely dispersed fleets dominated by small-scale vessels, a huge number of landing points, multispecies fisheries, and insufficient compliance and cooperation among countries in fisheries management. Despite this, there have been important improvements and achievements recently in the management of Mediterranean and Black Sea fisheries.
First and foremost, most countries in the region are becoming increasingly active in fisheries management. They are introducing national measures for fisheries management and participating more actively in regional and subregional initiatives. Most countries regularly participate in the meetings of the GFCM and send representatives to the stock assessment Working Groups of the GFCM Scientific Advisory Committee and to the subregional stock assessment Working Groups organized by the FAO regional projects CopeMed, AdriaMed, MedSudMed and EastMed. The EU established a Mediterranean subgroup of its STECF in 2006 to provide fisheries management advice on the Mediterranean fisheries of its member countries. The work of this subgroup is complementing the work done by the GFCM’s SAC. These recent initiatives have led to an appreciable increase in the number of the fish stocks and fisheries that are scientifically assessed. In 2009 and 2010, 59 different stocks (48 demersal and 11 small pelagic fish) were formally evaluated by the GFCM’s SAC or by the STECF.
Biological State and Trend
To access all FIRMS State and Trend summaries available for this Area, please look at:
Status and Trend Summaries (extracted from reports)
The status of fish stocks and fisheries in the Mediterranean and the Black Sea are shown in Table D5
. They are assessed and managed at several levels in Area 37. Some smaller inshore fisheries are managed at the national level. However, regional fisheries are managed within the framework of the General Fisheries Commission for the Mediterranean (GFCM), the RFMO in charge of the Mediterranean and the Black Sea, and by the EU. The exceptions to this management arrangement are mostly the tunas and tuna-like species. These species are managed within the framework of the ICCAT. For statistical reporting and management purposes, the GFCM breaks the Mediterranean and the Black Sea down into 30 different regions, called Geographical Subareas (GSAs) (Figure B5.11).
In the most recent two sessions of the GFCM Sub-committee on Stock Assessment (GFCM, 2010, 2011b) and of the Mediterranean Subgroup of the EU’s Scientific and Technical Committee for Fisheries-SGMED (Cardinale et al., 2009; Cardinale et al., 2010), a total of 59 stocks from 13 of the most exploited species were formally assessed mostly with analytical models. The quality of these assessments was reviewed through the formal process of the GFCM’s Scientific Advisory Committee (SAC) or the EU’s Scientific, Technical and Economic Committee for Fisheries (STECF) (Table B5.1
). The majority (78 percent) of the stocks assessed in the region in 2009 and 2010 were considered to be overexploited, with 22 percent fully exploited or non-fully exploited. The situation differed between demersal and small pelagic fish. Practically all demersal fish and crustaceans stocks assessed were classified as overexploited. In contrast, almost 70 percent of the small pelagic fish stocks were classified as fully exploited or non-fully exploited (Table B5.1
). Given the high intensity of fishing practised across the whole region, it is reasonable to assume that this is also the general situation for most of the nonassessed fish stocks. The exceptions are possibly the stocks off some less-fished regions in the Mediterranean, such as off the southeast coast and the deep waters in the east.
|Figure B5.11 Definition of the GFCM Geographical Sub-Areas (GSAs) Notes: 01 Northern Alboran Sea; 02 Alboran Island; 03 Southern Alboran Sea; 04 Algeria; 05 Balearic Islands; 06 Northern Spain; 07 Gulf of Lions; 08 Corsica Island; 09 Ligurian and North Tyrrhenian Sea; 10 South Tyrrhenian Sea; 11.1 Sardinia (west); 11.2 Sardinia (east); 12 Northern Tunisia; 13 Gulf of Hammamet; 14 Gulf of Gabes; 15 Malta Island; 16 South of Sicily; 17 Northern Adriatic Sea; 18 Southern Adriatic Sea; 19 Western Ionian Sea; 20 Eastern Ionian Sea; 21 Southern Ionian Sea; 22 Aegean Sea; 23 Crete Island; 24 North Levant; 25 Cyprus Island; 26 South Levant; 27 Levant; 28 Marmara Sea; 29 Black Sea; 30 Azov Sea |
European sprat, Mediterranean Sea
This is the most widely assessed species in the Mediterranean. Until the mid-1990s, high estimated juvenile mortality rates did not cause an obvious decline in recruitment. At the same time, catches were also increasing in both the east and west Mediterranean (Fiorentini, Caddy and de Leiva, 1997). It was suggested that this was because of the population of adult spawners surviving in some less exploited regions, the so-called spawning refugia (Caddy, 1990). However, after reaching their maximum (52 000 tonnes) in 1995, reported catches declined abruptly, to reach levels less than half of this maximum (about 21 000 tonnes) by 2003, recovering later to levels close to those of the early 1980s (Figure B5.6). The decline was associated with the systematic introduction of deep bottom gear (longlines and gillnets) that targeted the largest and most valuable fish (e.g. AdriaMed, 2005). The most recent stock assessment Working Groups (GFCM, 2011a; Cardinale et al., 2010) assessed the status of the stocks of this species in 11 GSAs. They concluded that all these stocks were being overexploited, with decreasing biomass and recruitment trends in many of these GSAs. The assessments recommended that both overall fishing mortality and the percentage of small fish in the catch should be reduced. This latter measure can be achieved through temporal closures of the nursery areas or gear modifications. Nevertheless, the importance of protecting a part of the adult spawning population has been identified several times as a way of improving the likelihood of sufficient recruitment to the population (e.g. Caddy, 1990; GFCM, 2011a).
Red (Mullus barbatus) and striped (Mullus surmuletus) mullets, Mediterranean Sea
During the latest meetings of the stock assessment Working Groups, the stocks of red mullet in 10 GSAs and of striped mullet in 3 GSAs were assessed (GFCM 2011a; Cardinale et al., 2010). All stocks were considered to be suffering overexploitation, with the exception of striped mullet in Malta Island, which was diagnosed as under full exploitation. The Working Group recommended a reduction in the overall fishing pressure and in the percentage of juveniles in the catches. It also recommended pursuing these reductions through changes to the gear or the protection of nursery areas.
Sparids, seabreams and pandoras, Mediterranean Sea
Sparids and seabreams play an important role in Mediterranean demersal fisheries and are generally heavily exploited. Analysis of data for Sparus aurata in the Gulf of Lions (Farrugio and Le Corre, 1994) suggested that it was fished above FMSY, and it is unlikely that this situation has improved. Pandora (Pagellus spp.) and groupers appear to be some of the demersal species least resistant to heavy exploitation, and catch rates have declined in a number of regions. Pandora stocks have been heavily overfished in Greek waters (Papaconstantinou, Mytilineou and Panos, 1988), and probably also in Cyprus. Other species overexploited in this region include bogue (Boops boops) and red mullet stocks (Hadjistephanou, 1992). In contrast, picarels (Spicara spp.) are considered to be exploited close to MSY. The stock of common pandora (Pagellus erythrinus) in GFCM GSA 09 (Ligurian and North Tyrrhenian seas) was assessed as overexploited by the SGMED WG in 2010 (Cardinale et al., 2010). The stocks of blackspot seabream (Pagellus bogaraveo) in the Alboran Sea were assessed by a joint Moroccan–Spanish working group within the framework of the CopeMed II project. The stock was classified as overexploited, although its status on the southern side is appreciably better than that on the northern side of the Alboran Sea (GFCM, 2011b). Finally, although bogue is a bycatch in many regions, it is targeted in several others, e.g. GSAs 03 and 26, and the stocks of this species in these regions were assessed as being overexploited in 2008–09. However, the situation of the species in other GSAs is probably slightly better.
Soles, Mediterranean Sea
The recent assessments undertaken in the framework of the AdriaMed project and by the GFCM stock assessment Working Groups indicate that sole (Solea solea) stocks in the Adriatic and the South Levant regions are heavily overexploited. The catches also include a large proportion of juveniles (GFCM, 2011a). The management recommendations for these two stocks include a reduction in the overall fishing mortality and reinforcement of closed areas during the peak recruitment periods to protect juveniles.
Horse and jack mackerels, Mediterranean Sea
Few data exist for horse mackerels (Trachurus trachurus and T. mediterraneus) as they are not a target species for the most fisheries in Area 37. They are apparently not intensively fished, except in Turkey and maybe some southwest Mediterranean countries. Their biomass appears to be variable, presumably responding to environmental fluctuations. They are migratory, but the patterns are unclear and this makes their assessment more difficult. Similar considerations apply to mackerels (Scomber scombrus and Scomber japonicus).
Norway lobster, Mediterranean Sea
Three stocks of this species were assessed in the most recent round of formal stock assessments (GFCM, 2011a; Cardinale et al., 2010). These stocks were those from GFCM GSA 05 (Balearic Islands), GSA 09 (Ligurian and North Tyrrhenian Seas) and GSA 17 (northern Adriatic, stock assessed in the framework of the AdriaMed project). All three stocks were found to be overexploited, requiring a reduction in fishing mortality, albeit to different degrees. This species is often captured by the fleets exploiting the deep-sea shrimps Parapenaeus longirostris and Aristeus antennatus, as well as larger hake (e.g. Sartor et al., 2003; Sbrana, Sartor and Belcari, 2003). Thus, the management of Norway lobster must take into consideration the multispecies nature of the fishery.
Rose shrimp, Mediterranean Sea
Rose shrimp (Parapenaeus longirostris) is exploited throughout the Mediterranean, and in most GSAs. During the last series of assessments, the stocks of this species in six GSAs B5. Mediterranean and Black Sea – FAO Statistical Area 37 85 were assessed, and the conclusion was that five (83 percent) of these were overexploited and one was fully exploited. This species is actively targeted in all these GSAs, but it is also sometimes captured as a bycatch of other fisheries (GFCM, 2011a). Therefore, management must take into consideration the multispecies nature of the fishery.
Small pelagic resources
Red shrimps, Mediterranean Sea
Red shrimps (Aristeus antennatus and Aristaeomorpha foliacea) are intensely exploited in the western and central Mediterranean by bottom trawlers fishing the continental slope. The most recent assessments could only analyse the state of the stocks of these species in two GSAs (Balearic Islands and Northern Strait of Sicily), which were considered to be overexploited. For some countries, significant amounts of Aristeus and Aristeomorpha are probably reported to FAO simply as “natantian decapods NEI”. Given the high economic value of this resource in the region (Lleonart et al., 2003), and the expansion in the fisheries targeting these species (Mouffok et al., 2008), special attention needs to be paid to the management of their fisheries.
Large pelagic resources
Sardine and anchovy, Mediterranean Sea
Monitoring of sardine and anchovy stocks with acoustic surveys has been done regularly for more than a decade in several regions. These regions include the Alboran Sea and Northwest Mediterranean, the Adriatic (with the support of the AdriaMed Project) and the Aegean and Black Seas (GFCM, 2011c). The daily egg production method (DEPM) is currently applied routinely to assess anchovy stocks in the Aegean Sea and less regularly in the Northwest Mediterranean, Tyrrhenian and Southern Adriatic. In general, the results are used as ancillary information to the acoustic surveys and the model-based stock assessments. In the latest meeting of the different stock assessment Working Groups dealing with small pelagic fish, a total of 11 assessments were presented and discussed (GFCM, 2011c; Cardinale et al., 2010). The assessments covered sardine and anchovy stocks in seven GSAs. Most stocks were found to be fully exploited. About 30 percent of the stocks were assessed to be overexploited, with those of both sardine and anchovy in the Gulf of Lions and the stock of anchovy in the Strait of Sicily considered to be in particularly poor condition. In the Gulf of Lions, this situation was associated with previous overexploitation and a current state of very low productivity. In contrast, excessive current fishing pressure is considered to be the main cause of low catch for the stock of anchovy in the Strait of Sicily.
The GFCM Small Pelagics Working Group (GFCM, 2011c) analysed the global variations of several small pelagic stocks and fisheries across the Mediterranean. It concluded that there were signs of some synchronous variations that suggested an environmental effect overlaying the effect of fisheries on the stocks. The Working Group suggested that this effect needed to be further investigated.
Large pelagic fish, being mostly migratory fish with extensive migration patterns covering several of the FAO Fishing Areas, are dealt with in Chapter C1.THE AZOV AND THE BLACK SEAS
Fisheries in the Azov and Black Seas are characterized mostly by the spectacular increase in catches of small pelagic fish from the 1970s to the mid-1980s and their subsequent collapse by the end of the 1980s. It is now reasonably accepted that the increase in catch was the result of a combination of eutrophication from the rivers draining into the seas and a reduction in predation pressure from heavy exploitation of the more important predators (Daskalov, 2002; Oguz, Fach and Salihoglu, 2008). The subsequent collapse has been linked to the invasion by the ctenophore Mnemiopsis leidyi coupled with heavy fishing pressure and environmentally unfavourable conditions for fish recruitment(Shiganova and Bulgakova, 2000; Oguz, Fach and Salihoglu, 2008). Top Black Sea predators such as dolphins and porpoises have seriously declined in abundance (Birkun, 2008). Predatory fish, including mackerel (Scomber scombrus), blue fish (Pomatomus saltatrix) and bonito (Sarda sarda) used to enter seasonally from the Sea of Marmara. Now, these species rarely penetrate into the waters to the northwest of the Black Sea (Zengin and Dinçer, 2006). The abundance of the stocks of these species can be considered severely reduced, but not necessarily only by fishing. Pollution, especially in the northwest part of the Black Sea, is considered to have played an important part (Mee, Friedrich and Gamoiu, 2005). Meanwhile, a species of grey mullet (the haarder [Mugil soiuy] has been introduced from the Pacific coast of the Russian Federation). This species breeds in shallow water and appears to be less sensitive to M. leidyi predation on its larval stages. This has allowed haarder stock size to increase in recent years. Several other introduced species, such as the Mya clam and Rapana sea snail appear to be tolerant of eutrophic conditions. The snail is now becoming a major export item in some countries and can be considered fully exploited (Shlyakhov and Daskalov, 2008). In the Azov Sea, collapses of several freshwater fish stocks, such as pike, bream and roach, occurred in the 1960s (Ivanov and Beverton, 1985). These collapses were associated with progressive salination caused by damming of, and water extraction from, major inflowing rivers. In the last decade, the amount of nutrients and pollutants entering the Black Sea through the river discharge has been appreciably reduced (BSC, 2008). This in turn has already resulted in a slight improvement in environmental conditions in the Black and Azov Seas in the last decade. This has allowed the recovery of biodiversity and marine living resources despite overfishing, degradation of vital habitats (including spawning and nursery areas) and the disturbance of the ecological balance that continues to occur. Although the regular yearly assessment of the major fish resources has not yet become a rule in the Black Sea, some particularly important resources have been the subject of more intensive study and more information on their status is available.Anadromous fish
Sturgeons, Azov and Black Seas
The estimated biomasses and catches of the most common species of sturgeon: Acipenser gueldenstaedtii, Acipenser stellatus and Huso huso have all declined recently. This decline has been accentuated drastically since the late 1980s. Two species of sturgeon (Acipenser brevirostrum and Acipenser nudiventris) have almost disappeared. Experts attribute these declines to the combination of a reduction in spawning habitats by damming of rivers, large-scale illegal fishing and the alteration of the flow regime of the main rivers (Shlyakhov and Daskalov, 2008). The estimated abundance of the Azov Sea sturgeon stock for 2004–05 was only 5 percent of that at the beginning of the 1990s (Shlyakhov and Daskalov, 2008). It is now considered that all the stocks of sturgeon in the Black and Azov Seas are very severely overexploited.
Small pelagic fish
Shads, Black Sea
Biomasses of these anadromous species have declined by about 75 percent or more compared with the 1970s. Unfavourable environmental conditions in the region’s rivers, especially the Danube River, may have affected the reproductive success of these species. However, overfishing on the northern and southern coasts of the Black Sea seems to have been the most important cause of the decline of these stocks (Radu, 2006). It is now considered that the stock of shad in the Black Sea is overexploited (Shlyakhov and Daskalov, 2008).
After the heavy exploitation of the larger predators in the Black Sea, small pelagic fish, especially sprat (Sprattus sprattus) and anchovy (Engraulis encrasicolus) became the most important fish resources in the Azov and Black Seas until their collapse in the late 1980s.
European sprat, Black Sea
The sprat stock in the Black Sea supported intensive fishing by the former Soviet Union in the 1950s and 1970s. More recent increases in exploitation rate have caused a decline in stock biomass that has also been linked to the increase in the abundance of the predatory ctenophore Mnemiopsis leydi in the late 1980s (Daskalov, 1998; Shiganova and Bulgakova, 2000). After the late-1980s stock collapse, sprat recruitment, biomass and catches started to increase again. The stock had recovered to the previous peak-level recorded in the 1980s by the mid-2000s. With the recovery of fishing, fishing mortality increased from 0.1 in 1990 to 0.3 in 2000. The catch reached close to its historic levels (~70 000 tonnes) in 2001–05. The decreasing CPUE and mean catch size in Bulgarian and Romanian fisheries in 2006–07 indicate that the current level of fishing pressure might be excessive for the current stock (Shlyakov and Daskalov, 2008).
Anchovy, Black Sea
Anchovy is the single largest marine resource in the Black Sea. The biomass increased in the late 1970s and early 1980s at a time when catches were also increasing. This was apparently in response to increased nutrient inputs to the Black Sea (Oguz and Gilbert, 2007) and a reduction in predators due to fishing (Daskalov, Prodanov and Zengin, 2007). Anchovy stocks collapsed in the late 1980s, probably as a result of the combined effect of intensive fishing and increased predation and feeding competition with the ctenophore Mnemiopsis leidyi (Oguz, Fach and Salihoglu, 2008). Fishing effort was subsequently reduced and this allowed anchovies to recover somewhat. However, anchovy biomass and catches have not returned to the previous levels. Despite this partial recovery, there is still substantial overcapitalization in anchovy fisheries, especially in the south and southeast of the Black Sea. It is believed that the stock of Black Sea anchovy is still being exploited above the level of sustainability.
Whiting, Black Sea
In the Black Sea, whiting (Merlangius merlangus) is caught mainly as a bycatch of trawl fisheries targeting sprat and other species. The exception is in Turkey and Romania, where it is also a target species for a part of the fleet. Catches of whiting have fluctuated markedly in the last two decades (Shlyakov and Daskalov, 2008). However, the condition of the stock varies in different parts of the Black Sea. In general, the stock seems to be more heavily exploited in the southwest Black Sea than in the northeast region, where it is apparently in a better condition. This stock may have benefited from the relative recovery of the small pelagic stocks that allowed both an increase in prey and a reduction in fishing pressure.
Turbot, Black Sea
Turbot (Psetta maxima) is the most important demersal species in the Black Sea, especially owing to its high value across the region. The stock of this species suffered very heavy exploitation in the 1970s and 1980s. It has partially recovered since then, as a result of increased restrictions on fishing being imposed by several nations, especially on the northern coasts of the Black Sea (Shlyakov and Daskalov, 2008). The latest information seems to indicate that this stock can be considered as fully exploited, although the components of the stock on the south coast may be overexploited already.
Among the species that have been introduced recently into the Black Sea, the Soiuy grey mullet (Mugil soiuy) and the sea snail Rapana thomasiana make the largest contribution to Black Sea fisheries. The catches of both of these species have been increasing following increased fishing effort. They are considered to be fully exploited, after the introduction of regulations limiting their exploitation on the northern coasts of the Black Sea. The intensive use of dredges for the fishery of sea snail, however, may be causing other damage to benthic habitats that should be closely monitored (Shlyakov and Daskalov, 2008).
Source of information
Marine and Inland Fisheries Service, Fisheries and Aquaculture Resources Use and Conservation Division. FAO Fisheries and Aquaculture Department “Review of the state of world marine fishery resources” FAO FISHERIES AND AQUACULTURE TECHNICAL PAPER.
No. 569. Rome, FAO. 2011.
The bibliographic references are available through the hyperlink displayed in "Source of Information".ACKNOWLEDGEMENTS
The authors would like to thank Enrico Arneri, Juan Antonio Camiñas, Constantina Riga, Nicoletta Milone, Luca Ceriola, Mark Dimech and Mathieu Bernardon, from the FAO Mediterranean fisheries management support projects, for their valuable comments and inputs. Special thanks also to the GFCM Secretariat and all the colleagues from the Fisheries Research Institutes of Mediterranean and Black Sea countries, who along the years have maintained high-quality fisheries research and data management programmes providing the information this review is based on, because without their work there would still be no scientific knowledge on the status of exploited fish stocks in this region.