Scottish Association for Marine Science
PO Box 3, Oban PA34 4AD, United Kingdom
For the purposes of this study, deep water is defined as deeper than about 400m. Some oceanic pelagic sharks may descend into these deeper waters, but they are specifically excluded from this study which is only concerned with the demersal, or benthopelagic, sharks. These fishes, described by Compagno (1990) as those taken in ‘offshore, deep-trawling operations by international fleets and local line fisheries that take poorly known, slow growing dog-fishes and other deep-water chondrichthyans for human consumption, fish meal and squalene liver oil’, are considered to be among those most at risk.
Data on specific deep-water sharks and their fisheries is sparse because data on their landings are frequently only described as ‘sharks various’, etc. Even if the place of capture is known, it can be difficult to even guess the species being landed without knowing something about the fishery. For example, ‘sharks various’ reported from southwest of Ireland could be a pelagic bycatch of the tuna fishery, a demersal bycatch of the hake longline fishery, a targeted longline fishery for sharks or a bycatch of the deep-water bottom trawl fisheries. The bycatch of many shark species is discarded, sometimes after only removing the liver or fins. Data that might enable estimates to be made of the proportion of the landings attributable to demersal sharks are sparse and often unavailable. This study relies heavily on the author's knowledge of the eastern Atlantic and Mediterranean, based on his coordination of a European Union funded FAIR Project - Developing deep-water fisheries: data for their assessment and for understanding their interaction with and impact on a fragile environment (Deep-fisheries CT 95–655).
For the purposes of this review, the available information is grouped by FAO Statistical Areas or combined areas (Figure 1). Within each area, the information is subdivided into (i) Lists or reference works on the demersal sharks of the area (ii) Survey data and (iii) Information on fisheries, including targeted fisheries, bycatch and discards. A separate section discusses management and conservation issues.
2. AREA DATA
2.1 FAO Statistical Area 27 - Northeastern Atlantic
2.1.1 Area, the deep-water demersal shark species and surveys
This statistical area has the same coordinates as the ICES Area. Figure 2 shows the ICES Area divided into sub-Areas and Divisions.
The deep-water shark species in this statistical area are well-documented (Whitehead et al. 1984). Several genera are in need of revision. The genus Apristurus is represented by two, or perhaps three, species (Haedrich and Merrett 1988). Nakaya and Stehmann (1998) have recently described a light coloured species as Apristurus aphodes. An annotated checklist of the fishes of the Azores has recently been published (Santos et al. 1997). A useful summary of the key distribution and biological data of 27 of the relatively common deep-water sharks from the ICES Area is given in Anon (1997a).
The deep waters of the northeastern Atlantic have been extensively surveyed by both bottom trawl and longlines. In view of the great diversity of deep-water habitats, ranging from the cold Arctic waters to the upwelling on the Iberian slope and the isolation of the Mid-Atlantic Ridge, the area has been subdivided into areas with broadly similar features.
FAO Fisheries Statistical Areas
2.1.2 Survey data
18.104.22.168 Rockall Trough and Porcupine Seabight
The Rockall Trough is probably one of the most surveyed deep-water areas. Some of the surveys date back to the latter part of the 19th Century. However, the most comprehensive data result from surveys that began in the 1960s and 1970s.
The United Kingdom: In 1973 and 1974 the UK Ministry of Agriculture Fisheries and Food (MAFF) carried out a wide-ranging bottom trawl survey of the Rockall Trough and adjacent areas (Figure 3). Bridger (1978) summarised some of the deep-water shark data in terms of overall size range and trends in catch rates by season and depth. Much of the detailed information from these survey cruises and from a later survey in 1978 remained in logbook format. In the 1990s the importance of these surveys, which pre-date the present deep-water trawl fisheries, was recognised as these fisheries have an important bycatch of demersal sharks. In a project jointly funded by the European Commission and the Scottish Association for Marine Science, all the catch and biological data were extracted and stored in a database (Gordon and Swan 1997a). Gordon and Swan (1997a) have also analysed the catch rates (no/hr and kg/hr) of sharks in the MAFF surveys by bathymetric zone and separately for ICES sub-Areas VI and VII.
Beginning in 1975, the Scottish Association for Marine Science (SAMS) carried out a series of trawl surveys in the Rockall Trough but unlike the MAFF surveys, these focused on seasonal studies of a discrete area known as the Hebridean Terrace. Full details of the methods used and the results of these surveys have been published (Gordon and Duncan 1985; Gordon 1986; Gordon and Duncan 1987; Gordon and Mauchline 1990; Gordon and Bergstad 1992; Gordon and Swan 1993; Gordon et al. 1996; and references cited therein). Comparisons of catch composition with different rawl types have been an important aspect of these studies and the catch rates of the different shark species by bathymetric zone and gear type are given in Table 1 (a-1).
The ICES Area showing sub-Areas and Divisions
The deep-water area surveyed by the UK MAFF in 1973 and 1974
The abundance and biomass of deep-water sharks by bathymetric zone and by gear type in SAMS surveys of the Rockall Trough. The upper number in each cell is the number or weight (kg) per 1000 m2. The lower number is the percentage of the total catch of all fish species. The gear codes are GT(L) = Granton trawl with long bridles; GT(S) = Granton trawl with short bridles: OTSB(P) = Semi-balloon trawl fished on paired warps: OTSB(S) = Semi-balloon trawl fishedon a single warp.
For details of the trawls see Gordon and Bergstad (1992).
(a) Rockall Trough 500m Bathymetric Zone - Abundance
(b) Rockall Trough 500m Bathymetric Zone - Biomass
(c) Rockall Trough 750m Bathymetric Zone - Abundance
(d) Rockall Trough 750m Bathymetric Zone - Biomass
(e) Rockall Trough 1000m Bathymetric Zone - Abundance
(f) Rockall Trough 1000m Bathymetric Zone - Biomass
(g) Rockall Trough 1250m Bathymetric Zone - Abundance
(h) Rockall Trough 1250m Bathymetric Zone - Biomass
(i) Rockall Trough 1500m Bathymetric Zone - Abundance
|Apristurusspp.||Not surveyed||Not surveyed||0.0794||0.0113|
|Etmopterus princeps||Not surveyed||Not surveyed||0.0367||0.0678|
|Centroscyllium fabricii||Not surveyed||Not surveyed||0.0367||0.0735|
|Centroscymnus coelolepis||Not surveyed||Not surveyed||0.0305||0.0057|
(j) Rockall Trough 1500m Bathymetric Zone - Biomass
|Apristurus spp.||Not surveyed||Not surveyed||0.0389||0.0009|
|Etmopterus princeps||Not surveyed||Not surveyed||0.0170||0.0403|
|Centroscyllium fabricii||Not surveyed||Not surveyed||0.0096||0.0141|
|Centroscymnus coelolepis||Not surveyed||Not Surveyed||0.2260||0.0509|
(k) Rockall Trough 1750m Bathymetric Zone - Abundance
|Etmopterus princeps||Not surveyed||Not surveyed||0.0546||0.0217|
|Apristurus spp.||Not surveyed||Not surveyed||0.0273||0.0145|
|Centroscymnus coelolepis||Not surveyed||Not surveyed||0.0036|
(l) Rockall Trough 1750m Bathymetric Zone - Biomass
|Etmopterus princeps||Not surveyed||Not surveyed||0.0136||0.0080|
|Apristurus spp.||Not surveyed||Not surveyed||0.0123||0.0074|
|Centroscymnus coelolepis||Not surveyed||Not surveyed||0.0387|
Similar surveys were carried out in the Porcupine Seabight in the 1980s and full details are given in Merrett et al. (1991a, b). Table 2 (a-j) shows the catch rates of the different shark species by bathymetric zone and gear type.
Gordon and Swan (1997b) have summarised all the depth distribution data of the main shark species from these three UK surveys. A simplified version of the combined data is given in Table 3
The Fisheries Research Services Marine Laboratory at Aberdeen has unpublished data from deep-water gear trials and surveys carried out in the Rockall Trough in 1997 and 1998. As a contribution to the EC FAIR Deep-fisheries Project, all the UK survey data are being compiled by SAMS.
The abundance and biomass of deep-water sharks by bathymetric zone and by gear type in SAMS/IOS surveys of the Porcupine Seabight. The upper number in each cell is the number or weight kg)/1000m2 The lower number is the percentage of the total catch of all fish species. The gear codes are GT(L) = Granton trawl with long bridles; OTSB(S) = Semi-balloon trawl fished on a single warp. For details of the trawls see Gordon and Bergstad (1992).
(a) Porcupine Seabight 500m Bathymetric Zone - Abundance
(b) Porcupine Seabight 500 m Bathymetric Zone - Biomass
|Etmopterus spinax||0.0017||Not weighed|
|Galeus melastomus||0.0011||Not weighed|
|Dalatias licha||0.0004||Not weighed|
(c) Porcupine Seabight 750m Bathymetric Zone - Abundance
(d) Porcupine Seabight 750m Bathymetric Zone - Biomass
|Deania Calcea||0.1976||Not weighed|
|Etmopterus spinax||0.0135||Not weighed|
|Scymnodon ringens||0.0572||Not weighed|
|Galeus melastomus||0.0159||Not weighed|
|Centrophorus squamosus||0.0658||Not weighed|
|Dalatias licha||0.0001||Not weighed|
|Centroscymnus coelolepis||0.0738||Not weighed|
(e) Porcupine Seabight 1000 m Bathymetric Zone - Abundance
(f) Porcupine Seabight 1000m Bathymetric Zone - Biomass
|Deania calcea||0.1113||Not weighed|
|Scymnodon ringens||0.0589||Not weighed|
|Centroscymnus coelolepis||0.1383||Not weighed|
|Galeus melastomus||0.0057||Not weighed|
|Apristurus spp.||0.0011||Not weighed|
(g) Porcupine Seabight 1250m Bathymetric Zone - Abundance
(h) Porcupine Seabight 1250m Bathymetric Zone - Biomass
|Centroscymnus coelolepis||0.4815||Not weighed|
|Centroscymnus crepidater||0.0026||Not weighed|
|Galeus murinus||0.0024||Not weighed|
|Deania calcea||0.0124||Not weighed|
|Apristurus spp.||0.0041||Not weighed|
(i) Porcupine Seabight 1500m Bathymetric Zone - Abundance
|Centroscymnus coelolepis||Not surveyed||0.0188|
|Etmopterus spinax||Not surveyed||0.0021|
|Apristurus spp.||Not surveyed||0.0021|
(j) Porcupine Seabight 1750m Bathymetric Zone - Abundance
|Etmopterus spinax||Not surveyed||0.0041|
|Centroscymnus coelolepis||Not surveyed||0.0041|
|Etmopterus princeps||Not surveyed||0.0021|
|Scientific name||Depth range (m)|
|Centrophorus squamosus||458 – 1216|
|Centroscyllium fabricii||677 – 1545|
|Centroscymnus coelolepis||366 – 1750|
|Centroscymnus crepidater||484 – 1310|
|Dalatias licha||366 – 1360|
|Deania calcea||458 – 1260|
|Etmopterus princeps||689 – 1861|
|Etmopterus spinax||386 – 999|
|Scymnodon ringens||500 – 1109|
|Apristurus spp.||721 – 1760|
|Galeus melastomus||245 – 1033|
|Galeus murinus||940 – 1260|
Germany: Germany also carried out extensive bottom trawl surveys in the 1970s and 1980s. The area surveyed was similar to that shown in Figure 1. No detailed information on the shark catches has been published, but Ratz (1984) gives summarised data of some of the earlier cruises. Ratz divided the area into three; northern slopes, southern slopes and offshore slopes around the Rockall Plateau. For each of these areas, he gives mean catch rates (number and weight per square nautical mile) for each species by 100m bathymetric zone. Gordon and Swan (1997b) have summarised these data for each shark species and the data for all species combined is given in Table 4. These survey data have been reanalysed as the Institut fur Seefischerei contribution to the EC FAIR Deep-fisheries Project.
|Depth zone (m)||Southern slope||Northern slope||Rockall slopes|
France: France carried out bottom trawl surveys in the 1960s but little information has been published. A new survey was carried out in 1996 and Allain and Kergoat (1997) have provided a list of all the fish species, including sharks, which were caught. Few data exist for the commercial fishery, however, within the “official” statistics, the data for the category “siki” are as follows:
|Year||Landings (t)||Value (FF millions)|
These data show that the catches have already started to decrease but it is not possible to say if this is caused by overfishing or market fluctuations. The 3 landing ports involved are Boulogne/Mer (55% of landings), Lorient (27%) and Concarneau (18%). Landings at the last two ports started in 1995.
Ireland: The Fisheries Research Centre began a deep-water survey programme in 1993 using a chartered trawler. A total of eight trawl and longline surveys have been completed (Connolly and Kelly 1994, 1997; Kelly et al. 1997; Connolly 1997; Clarke 1997). In addition to providing material for biological studies on deep-water species, including sharks, these surveys have been used to study discards, of which sharks are an important component (Connolly and Kelly 1996).
Norway: In 1991 Norway carried out an experimental deep-water longline survey to the west of the British Isles (Stene and Buner 1991). Sharks comprised a significant part of the total catch by weight (20–85%), depending on the area. The data on the sharks have been extracted from the report and have been summarised by Gordon and Swan (1997b) (Table 5).
22.214.171.124 Norwegian Sea (including Faroe Shetland Channel, the Norwegian Deeps and the deep water of the Skagerrak)
No shark species were encountered in the trawling surveys of the western Norwegian slope (Bakken et al. 1975; Baliño et al. 1993; Bergstad et at. 1998). However, in the Norwegian Deeps and the deep water of the Skagerrak, Etmopterus spinax, Squalus acanthias, Scyliorhinus caniculus and Galeus melastomus have been recorded (Bergstad 1990).
126.96.36.199 Iceland and Faroe Islands
In this area the composition of the deep-water fish fauna is influenced by the water masses (Magnússon 1998). Most of the sharks occur in the Atlantic water masses. The main deep-water shark species which have been recorded in Icelandic deep-water bottom trawl surveys are Centroscymnus coelolepis, Centroscyllium fabricii, Etmopterus princeps, Deania calcea and Centroscymnus crepidater (Magnússon and Magnússon 1995). Other species mentioned are Centrophorus squamosus, Apristurus laurussonii and Somniosus microcephalus. In a deep-water trawl survey of the Reykjanes Ridge in 1993, sharks comprised 3.5% of the total catch by weight.
Jakobsdóttir (1998) has described the distribution and biology of Centroscyllium fabricii and Etmopterus princeps from ten Icelandic deep-water bottom trawl surveys between 1992 and 1997. Two surveys in 1996 and 1997 were for Reinhardtius hippoglossoides (Greenland halibut), but some effort was also placed on analysing the shark bycatch. Both species had a similar depth distribution between 800 and 1200m and bottom temperature was an important factor in determining the distribution. Both species, especially C. fabricii, comprise a significant component of the discarded bycatch in the Greenland halibut fishery (Table 6).
Other deep-water demersal sharks reported from Icelandic waters are Galeus murinus, Pseudotriakis microdon, Etmopterus spinax, Dalatias licha and a doubtful record of Scymnodon obscurus (Jónsson 1975).
Reinert (1995) has analysed the total catch of Faroese bottom trawl surveys for stations >500m and gives details of frequency of occurrence and relative abundance. Details are also given of an exploratory longline survey. The sharks caught by each gear are shown in Table 7.
|Species||Station 2||Station 3||Station 4||Station 5||Station 7||Station 8||Station 10||Station 11|
|coelolepis Deania calcea||39.1||14.1||15.2||15.9||8.9||2.1||42||0|
|Wt (kg) per 1000 hooks||800||340||400||1020||1080||1170||390|
|Catch (kg)||%||Catch (kg)||%|
188.8.131.52 East Greenland
A deep-water longlining survey to the east of Greenland at depths down to 1000m yielded only two species of deep-water lantern sharks, Etmopterus pusillus and Etmopterus spinax in small quantities (Hareide 1991). A bottom trawl survey off East Greenland of depths between 200 and 1000m only recorded Centroscyllium fabricii (Yatsu and Jørgenson 1988).
184.108.40.206 Mid-Atlantic Ridge
In a review of trawl and longline surveys carried out in the international sectors of the Mid-Atlantic Ridge and the Reykjanes Ridge, Hareide and Thomsen (1997) record the following species; Chlamydoselachus anguineus, Dalatias licha, Hexanchus griseus, Oxynotus paradoxus, Galeus melastomus, Pseudotriakis microdon, Centrophorus squamosus, Centroscymnus coelolepis, Deania calcea, Etmopterus princeps, Etmopterus spinax, Centroscyllium fabricii, Etmopterus pusillus and Centrophorus lusitanicus. Biological information is given for Centrophorus squamosus, Centroscymnus coelolepis and Deania calcea. Hareide and Garnes (1998) give catch rates of all fish species caught by both trawl and longline surveys in five areas of the Reykjanes and Mid-Atlantic Ridges. The shark data are summarised in Tables 8 to 13.
The northern Reykjanes Ridge (61-62°N) was sampled by bottom longline. Catches of Centroscyllium fabricii were variable, but in some instances accounted for almost the total catch of a set (Table 8). Further south on the Reykjanes Ridge (54–56°N) fishing was by both bottom and vertical longlines and Etmopterus princeps was sometimes the dominant species, especially at night (Table 9). E. princeps was a dominant species in bottom and vertical longline sets on the Hecate Seamount (52°N) (Table 10). Trawling on the Faraday Seamounts (59°N) was extremely difficult, but nevertheless there were some large catches of E. princeps (Table 11). Trawling north of the Azores (43–44°N) yielded a variety of deep-water sharks (Table 12). Longline sets north of the Azores (43– 44°N) showed that Centrophorus squamosus was a dominant species between 400 and 900m, whereas Centroscymnus coelolepis and Centroscymnus crepidater were dominant between 900 and 1300m (Table 13).
As part of a study on the design optimisation and implementation of demersal cruise surveys of the Macaronesian Archipelagos, longline surveys were carried out around all the islands and fishing banks of the Azores in the spring of 1995 and 1996 (Menezes et al. 1997). The mean catch rates by area and depth are given in the report. A sumrtiafy of the total number and weight of sharks caught in each survey is given in Tables 14 and 15. An intensive fishing experiment on a seamount in the Azorean archipelago was carried out in 1996 (Silva and Menezes 1996). Deania profundorum, Etmopterus spinax, Etmopterus pusillus and Dalatias licha were recorded.
|Species||Number of individuals||Weight (kg)|
|Species||Number of individuals||Weight (kg)|
The Instituto Español de Oceanografia has carried out annual demersal surveys in the Galician and Cantabrian Seas and since 1994 some of the trawls have been in deep water. Data on species composition, total catch, and catch-per-unit-effort for deep-water elasmboranchs caught by the R.V. Cornide de Saavedra are given in Table 16. Most elasmobranchs were found in depths greater than 400m.
Demersal surveys have also been carried out in the Gulf of Cadiz and CPUE data are available for the following sharks that occur at depths greater than 400m: Centrophorus granulosus, Dalatias licha, Deania calcea, Etmopterus spinax, Galeus melastomus and Scyliorhinus canicula. Deep-water exploratory surveys were carried out in 1994 in ICES sub-Areas VI, VII and XII and CPUE data by depth zone and fishing area are available for Centroscymnus coelolepis, Etmopterus princeps, Scymnodon obscurus, Apristurus maderensis and Galeus melastomus. In 1996 a deep-water exploratory survey (EXP96) was carried out on the Galician Slope (ICES Divisions VIIIc and IXa). Catch and CPUE data are available for Deania calcea, Galeus melastomus and Scymnodon ringens for two areas and for bathymetric zones corresponding to 500–914 m and 914–1400 m (EC FAIR 95–655-unpublished reports).
As a contribution to the EC FAIR Deep-fisheries Project, a stratified sampling programme was carried out along the entire Portuguese continental slope. The area was subdivided into 5 sectors and a variable number of subsectors. Within each of these divisions, hauls were separated into depth strata which were generally of 100m. Mean yields (kg/hr) for each stratum are available for Galeus melastomus, Deania calcea, Centrophorus granulosus and Dalatias licha (EC FAIR 95–655 unpublished reports; Viriato et al. 1997; Correia et al. 1997).
2.1.3 The fisheries
220.127.116.11 Rockall Trough and Porcupine Seabight
The only deep-water demersal shark species which are routinely landed from the bottom trawl fisheries to the west of the British Isles are Centrophorus squamosus and Centroscymnus coelolepis and they are collectively known as ‘siki’. Landings of other species such as Dalatias licha, Deania calcea, Centroscymnus crepidater and Centroscyllium fabricii are of only minor importance.
All the French landings of siki are from the deep-water trawl fisheries and most are from ICES sub-Areas VI and VII. Landings by the French fleets have increased from almost 400t in 1990 to over 3000 t in 1996 (Lorance and Dupouy 1998). The landings of siki at the French port of Concarneau are being sampled by the Marine Laboratory of the Collège de France as a contribution to the EC FAIR Deep-fisheries Project. The results indicate that there are seasonal differences in the proportion of both species in the landings. Length compositions by sex of both species have been recorded. There is a lack of juvenile and gravid females of Centrophorus squamosus in the trawl catches. A summary of French data availability is given in Anon. (1996a).
|Species||Year||Number of hauls||Weight (g)||CPUE g/30min||Specimens number|
|1998||6||18 552||3 092||70|
|Deania calceus||1994||6||3 180||530||9|
|1995||10||106 935||10 694||75|
|1996||11||37 080||3 371||77|
|1997||8||11 880||1 485||16|
|1998||6||12 030||2 005||32|
|Galeus melastomus||1994||6||1 890||315||11|
|1997||8||9 215||1 152||28|
|1998||6||18 005||3 001||71|
|Scymnodom ringens||1994||6||1 830||305||3|
|Hexanchus griseus||1994||6||4 170||695||2|
Lorance and Dupouy (1998) have identified three main fleets in the deep-water fishery and illustrate the difficulties associated with CPUE indices for assessment purposes in this developing fishery where technology, increasing knowledge of the fishing grounds etc., cause changes in efficiency and hence CPUE. One fleet of larger trawlers that had changed little during the development of the fishery was considered to give the best estimates of CPUE. There has been a decline in CPUE for all species, but the deep-water squalid sharks appeared to be the most resilient to change, perhaps because they live over widely dispersed areas (Table 16).
Iglesias and Paz (1995) and Piñeiro et al. (1998) have described some recent developments in the Spanish fishery for deep-water sharks in this area. A deep-water longline fishery for sharks in ICES sub-Areas VI and VII began in 1991 and was dependent on the high value of the liver oils. The fleet involved in this fishery were longliners that previously fished for Merluccius merluccius. Many operate under foreign flags, but most of the landings are in the Galician port of La Coruña. The sharks captured included Somniosus rostratus, Deania calcea, Centrophorus granulosus and Centroscymnus coelolepis. Table 17 shows the combined landings of all species into the port of La Coruña and Table 18 the landings of deep-water sharks from the longline fishery in ICES sub-Areas VI and VII.
18.104.22.168 Reykjanes and Mid-Atlantic Ridges and Hatton Bank
Landings of deep-water sharks have been recorded from ICES sub-Area X but the species are not recorded and it appears that most are probably from Spanish vessels fishing on the Hatton Bank (Hareide and Thomsen 1997). In the second half of 1996, five Spanish trawlers began a multi-species deep-water fishery in ICES sub-Area XII (Hatton Bank). The estimated shark catches, which were mostly Centroscymnus coelolepis, for 1996 and 1997 were 534 and 554t, respectively. The corresponding catch rates were 79.7 and 65.7kg/hr and the shark discards were 1.6 and 2.1t, respectively (Piñeiro et al. 1998).
Dalatias licha in the Azores occurs at depths of between 150 and 200 m, with a deepest record of 500m. In 1981 the recorded catch was 2239t1 which accounted for 19% of the total Azorean catch of all species (Silva 1983). It was second in importance only to the blackspot seabream (Pagellus bogaraveo). In 1981 it was fished only around three of the islands, Pico, Faial and San Miguel. The traditional method of fishing was by vertical longlines, but in 1981 it was reported that some larger vessels were using nets. The flesh was dried and exported to mainland Portugal. The livers, which account for about 20% of body weight, are rich in squalene. The liver oil was also exported. A preliminary assessment of the stock using an estimated CPUE adjusted for variables such as fluctuating market demand led to the conclusion that the catch was close to Maximum Sustainable Yield (MSY) in 1981 and that it would be unwise to further increase catches.
In a further paper Silva (1987) carried out an assessment based on catch and effort data for the years 1977–1886 taking into account the sexual dimorphism in size and gear selectivity and estimated the MSY for both sexes combined at 933t/yr. Anderson (1990) gives a summary and evaluation of both these papers. He concludes that the assessment appears to be valid because it is a well-defined directed fishery and that there is a strong likelihood that a unit stock is being considered. However, he did consider that the time-series of catch and effort data was too short.
1 This figure appears to be incorrect. Later in the paper a figure of 543t is given for the catch in the two of the most important areas In Anon. (1995a) the total catch of this species from the Azores (sub-Area X is given as 947t.
The landings of Dalatias licha at the Azores for the years 1977–1994 are given in Table 19 (Anon. 1995a). Data provided to the ICES Study Group on Elasmobranch Fishes, but only shown in graphical format in the Report, suggest there has been a dramatic decline in landings between 1995 and 1997 (Anon. 1998a). This report also provides information on the value of the landed catch and the distribution of the catch between the Azorean islands.
22.214.171.124 East Greenland
At present there is no directed fishery directed for sharks in Greenland waters. Somniosus microcephalus is taken as bycatch in both the inshore and offshore longline fishery for Greenland halibut and in the offshore trawl fishery for shrimps and Greenland halibut. Almost all the sharks are discarded and not recorded. A few S. microcephalus, taken as bycatch in the East Greenland shrimp fishery, are landed in Iceland and some are used as dog food in Northwest Greenland, although the amount is not known (Jorgensen, Pers. Comm.).
There was a commercial longline fishery for S. microcephalus during the first half of the century and the landings of liver were about 700t/yr in the period 1931–1939 but decreased thereafter (Hansen and Hermann 1953). There have been a number of trial and research fisheries over the years but they are not well documented. Centroscyllium fabricii must be taken as a bycatch in the commercial trawl and longline fisheries, but the amounts are not recorded.
126.96.36.199 Iberian Peninsula
Spain2: Since 1996 two longliners have fished for deep-water sharks in ICES Divisions VIIIc (Cantabrian Sea), VIIIabd and IXa throughout the year. These vessels are based at the ports of Fisterra and Aviles. Other longliners operate a seasonal fishery for sharks between October and March and the most important harbour is San Vicente de la Barquera (Piñeiro et al. 1998). The species landed are Scyliorhinus canicula, Galeus melastomus, Centrophorus spp., Etmopterus spp., Dalatias licha and Deania calcea. The livers are the most valuable commodities, but the fins and body are used for human consumption and the skin of some species is retained. The total landings of sharks of all species into northwestern Spanish ports from ICES Divisions IXa, VIIIc and VIIIabd has increased from 31t in 1991 to 483t in 1997. The fleet composition is diverse with a wide range of size and power. The landings of each species of shark from the longline fishery in ICES Divisions VIIIabd for 1996 and 1997 are shown in Table 20.
In 1996 an experimental survey in deep waters was carried out in the Northwest of the Spanish continental slope (ICES Divisions IXa and VIIIc) by commercial trawlers of the Spanish fleet, during August and September 1996. The catches and CPUEs by deep strata and Division of deep-water sharks are shown in Table 20. In 1997 three small trawlers also began trawling in a sporadic way on the Galician continental slope (Division IXa). Between January and August 1997 they landed 1375 kg of Galeus melastomus and 3183kg of Deania calcea.
2 Much of the information provided here was obtained through the Deep-water fisheries project (EC FAIR PROJECT CT 95–0655).
|ICES Division Ixa|
|Depth strata||500–914||914–1400||500–914||915–1400||All depths|
|ICES Division VIIIc|
Since 1997, a deep-water survey was carried out in ICES Division IXb by two Spanish longliners. The survey was conducted from August to October and in April of 1998; the depth range explored was between 600 and 1400m. One longliner targeted deep-water sharks over dephs greater than 900m. The catches and CPUE for this ship are given in the Table 21.
|Depth strata||900–1000 m||<1000m|
|Species||Kg/1000 hooks||N/1000 hooks||Kg/1000 hooks||N/1000 hooks|
|10 900 hooks||21 300 hooks|
In ICES Divisions IXa, VIIIc and VIIIabd, with the exception of one longliner in Fisterra, the other longliners (around 10) involved in this fisheries, target deepwater shark seasonally (mainly from October to March). The species captured are mainly: Deania calceus Dalatias licha, Centrophorus sp., Centroscymnus sp. The landings since 1991 to 1998 of the most important ports in Cantabrian Sea and North West of Spain (La Coruña, Cariño, Ondarroa , San Vicente de la Barquera S.V.B and Avilés AV) are shown in Table 22. From 1996 and 1997 it was possible to estimate the preliminary landings by species (Table 23). Since 1996 information on S. Acanthias and G. galeus has become available previously it was not disaggregated.
* Preliminary data
|Main harbours||Year||Fishing area||Galeus Melastomu s||Centrophorus Squamosus||C. coelolepis and D. calceus||S. acanthias and G. galeus||C. fabricii|
|La Coruña||1996||VII-VIIIab||400 703|
|Finisterre1||1996||VIIIc and Ixa||18 552||15 804|
|S.V. Barquera||1996||VIIIc||512||15 862||23 791|
|S.V. Barquera||1996||VIIIab||13 626||36 455|
|Marín y Vigo2||1997||VII||738 635|
|Marín y Vigo2||1997||Ixa||50 618|
|S.V.B and AV||1997||VIIIc||60 779||91 169||395|
|S.V.B and AV||1997||VIIIab||220 474||58 607||1 579|
1 Estimated from first semester.
2 Preliminary data.
The new directed deep-water fishery, established in Bay of Biscay (ICES Divisions VIIIa,b,d) began in 1996 year. The deep-water shark landings from 1996 and 1997 are shown in the Table 24.
|Squalus acanthias||80 200||98 580|
|Centrophorus squamosus||136 626||142 556|
|C. coelolepis and Deania calceus||36 455||38 123|
|Galeus melastomus||26 350|
|Raja spp.||1 320|
In the second half of 1996, five trawlers with conventional deep-water trawls started a new deepwater fishery in the northeast of Subarea XII, in an area called Hatton Bank. This fishery targets many species and is highly diversified. The majority of the fishing effort (76%) is between 1000 and 1500m. The estimated deepwater shark catch from 1996 and the preliminary data from 1997 are shown in the Table 25.
* About 76% of the effort are between 1000 and 1500m.
1 Mainly C. coelolepis
2 mainly E. princeps.
Starting from September of 1997 one trawler began to fish in deep-water on the continental slope to depths of about 1000m in ICES Subareas VII. This vessel alternates fishing deepwater and demersal species. The deep-water sharks catches are shown in the Table 26.
In the last year, three trawlers began to fish on the continental slope of Galicia (NW of the Spain, ICES Divisions IXa), but isolated way. The Table 27 shows the catches and effort of these vessels from 1997 year during January - August when they sporadically fished in deep waters.
|Number of ships||3|
|Number of hauls||18|
* These landings correspond to the captures of the sporadic trawls carried outin deep-waters
Mainland Portugal: The shark species recorded in the bycatch of the deep-water (200–600 m) crustacean trawl fishery off the south and south west coasts of Portugal are Galeus melastomus, Deania calcea, Etmopterus spinax, Dalatias licha, Centrophorus granulosus, Centrophorus squamosus and Etmopterus pusillus. Deep-water sharks are also a bycatch of the longline fishery for the black scabbardfish (Aphanopus carbo) off Sesimbra. The most important species are Centroscymnus coelolepis and Centrophorus squamosus. Other sharks caught are Dalatias licha. Deania calcea, Centrophorus granulosus and Scymnodon ringens. There is also a targeted longline fishery for deep-water sharks off northern Portugal close to the Spanish border. This takes place at depths ranging from 800 to 1400 m and most of the catch consists of Centrophorus granulosus. Other shark species caught in small quantities are Centrophorus squamosus and Centroscymnus coelolepis. However, in this fishery, which began in 1983, the catch rates have steadily declined since 1992 when six vessels took part in the fishery. Now only one longliner continues to fish for sharks all the year round. Livers are important to the viability of the fishery. Fishermen have been increasing the value of their catches by processing the sharks on board.
Moura et al. (1998) give details of the landings between 1992 and 1997 of four species of deep-water shark, Galeus melastomus, Dalatias licha, Centrophorus squamosus and Centrophorus granulosus for each port. Some information is also given of the landings by each gear type for the same period. The totals for all ports are given in Table 28.
|Galeus melastomus||16 054||20 143||36 964||29 481||34 922||28 959|
|Dalatias licha||10 994||11 024||10 828||7 420||4 303||3 634|
|Centrophorus squamosus||421 089||337 686||1 108 186||543 501||410 796||356 053|
|Centrophorus granulosus||682 157||555 148||183 498||192 730||121 648||189 590|
The shark landings from both the directed fishery and the bycatch of the black scabbardfish fishery have been the subject of a special study as part of the EC FAIR Deep-fisheries Project. Because the identification of sharks can cause problems and thus lead to inaccurate fishery statistics, routine market sampling has been undertaken. The identification of sharks in boxes selected at random from the market was verified. The results indicate that the errors in identification of sharks were small. During this sampling programme, biological information on length and sex was collected from the following species. Hexanchus griseus, Centroscymnus coelolepis, Dalatias licha, Deania calcea, Centroscymnus crepidater, Centrophorus granulosus, Centrophorus squamosus and Scymnodon ringens.
In a semi-pelagic “pedra-boia” longline fishery for Merluccius merluccius (hake) at depths between about 200 and 700m on the continental slope off the Algarve, several shark species are caught (Erzini et al. 1998). Galeus melastomus (23% of total numbers in the catch) was the most abundant. Etmopterus pusillus and Scyliorhinus canicula made up about 5% of the catch. With the exception of the larger specimens of Galeus melastomus, the remaining sharks were discarded or retained for use as bait in traps.
2.2 FAO Statistical Area 21 - Northwestern Atlantic
2.2.1 The deep-water demersal shark species
Templeman (1963) listed the following deep-water shark species in his review of the distribution of sharks in the Canadian Atlantic (with special reference to Newfoundland waters): Apristurus profundorum, Centroscyllium fabricii, Etmopterus princeps, Centroscymnus coelolepis, and Somniosus microcephalus. Other reviews are by Bigelow and Schroeder (1948, 1957). Haedrich and Merrett (1988) have summarised the distribution of all deep-living demersal fishes, including sharks, from two surveys of the continental slope off Newfoundland and the eastern coast of the United States. Three deep-water demersal sharks, Centroscyllium fabricii, Etmopterus spinax and Somniosus microcephalus, have been recorded from West Greenland (Hareide 1992).
2.2.2 Survey data
Snelgrove and Haedrich (1985) carried out a survey in the Carson Canyon region on the eastern edge of the Grand Bank of Newfoundland and only recorded one species of shark, Centroscyllium fabricii. Haedrich et al. (1980) also recorded only C. fabricii from a trawl survey of the continental slope south of New England. However the trawl used was small and used only a single warp. Thus, it would be inefficient for catching large mobile species such as sharks (Gordon and Duncan 1985). In a similar survey along a transect at 1000m in the Middle Atlantic Bight, C. fabricii was the only shark caught (Markle and Musick 1974).
Between 1995 and 1997, deep-water exploratory fishing has been carried out by a few commercial vessels along the continental slope, in canyons and on certain seamounts (Moore and Galbraith 1998). The main fishing area was from the Hudson Canyon to the northeastern Georges Bank. The fishing depth ranged from 310 to 1850m. Listed amongst the fish occurring in small numbers, but with potential commercial importance, were the deep-water sharks Centroscyllium fabricii, Centroscymnus coelolepis and Etmopterus spp.
There have been a number of trawl and longline surveys on the continental slope of west Greenland and also in some of the fjords (Jørgensen 1995). The only sharks recorded were Centroscymnus fabricii and Somniosus microcephalus, both of which were taken by trawl and longline. In another longline survey over a wide range of depths (300 to 2100m) on the continental slope of west Greenland, C. fabricii comprised about 1.5% of the total catch (Hareide 1992). S. microcephalus was also encountered.
2.2.3 The fisheries
There are no directed fisheries for deep-water demersal sharks in FAO Statistical Area 21. There are also no reported landings of demersal sharks as a bycatch of other fisheries. In a review of the potentially exploitable deep-water resources off Atlantic Canada, Pohle et al. (1992) considered that only Centroscyllium fabricii was sufficiently abundant to be of interest. They thought that there would be little demand for human consumption, but a fishery for oil (squalene) might have a small potential if catches were sufficiently large.
2.3 FAO Statistical Area 37 - Mediterranean
2.3.1 The deep-water demersal shark species
Whitehead et al. (1984) gives information on the shark species present in the Mediterranean.
2.3.2 Survey data
188.8.131.52 Catalan Sea
Stefanescu (1991) has recorded the presence of Hexanchus griseus, Galeus melastomus, Centroscymnus coelolepis Dalatias licha and Etmopterus spinax from the Catalan slope at depths greater than 1000m. There have been numerous surveys in this area in recent years and as a contribution to the EC FAIR Deep-fisheries Project all the data from these surveys have been collated in a unified database.
184.108.40.206 Balearic Islands
One of the main, long-established fisheries, around the Balearic Islands is a trawl fishery for deep-water crustaceans. Some of the deep-water sharks are landed (see below). As a contribution to the EC FAIR Deep-fisheries Project, the Institut Mediterrani d'Estudis Avançats, Mallorca, has been surveying a previously unfished deep-water area off the southern Balearic Islands. Table 29 gives details of the shark component of the catch.
220.127.116.11 Northwest Ionian Sea
In research surveys carried out in the northwestern Ionian Sea by the University of Bari as a contribution the EC FAIR Deep-fisheries Project, four species of demersal sharks were caught (Table 30). Galeus melastomus was the third most abundant of all the fish species caught and occurred at depths between 313 and 670m.
|Species||April 1996||June 1996||October 1996||February 1997|
18.104.22.168 The continental slope of Greece
In Greek waters Etmopterus spinax was caught in deep-water trawl surveys in the North Aegean and Thracian Seas, but not in the Ionian Sea. In the North Aegean it was found in the 300– 400m zone, whereas in the Thracian Sea it tended to be deeper than 400m. Also recorded in surveys on the upper slope were Scyliorhinus canicula and Squalus blainvillei (EC FAIR Deep- fisheries Project 95–655, unpublished reports).
In a new seasonal deep-water bottom trawl survey carried out in the South Ionian Sea as a contribution to the EC Deep-fisheries Project, the following sharks have been recorded: Dalatias licha, Etmopterus spinax, Galeus melastomus, Scyliorhinus canicula and Squalus blainvillei. Details of monthly changes in catch rates by bathymetric zone length distributions and depth ranges for G. melastomus, E. spinax and S. blainvillei have been recorded. Table 31 shows the total weight of all shark species caught during the survey. Monthly CPUE data for G. melastomus caught during the survey are given by Petrakis (1998).
22.214.171.124 Eastern Mediterranean
A monitoring survey of a deep-water dumpsite in the eastern Mediterranean caught specimens of Centrophorus squamosus, Galeus melastomus, Sommosus rostratus, Etmopterus spinax and Hexanchus griseus (Hornung et al. 1993).
2.3.3 The fisheries
Muñoz-Chápuli (1985) has analysed the catches of demersal sharks from trawlers operating in the Alboran Sea (western Mediterranean). Although separate records were kept for the northern and southern regions, the same species were present in both areas (D and E) of Table 32, only Squatina aculeata and Mustelus asterias were not found deeper than 200 m.
As a contribution to the EC FAIR Deep-fisheries Project, the monthly landings of all fish species landed as a bycatch of the deep-water crustacean trawl fisheries have been scientifically recorded in Majorca for 1996. These include the following sharks: Squalus spp., Scyliorhinus canicula, Galeus melastomus and Centrophorus granulosus.
A checklist of the sharks in the waters of the eastern tropical Atlantic is given in Quero et al. (1990). The following deep-water sharks have been recorded in Madeiran waters: Centrophorus squamosus, Centrophorus granulosus, Centroscymnus coelolepis, Centroscymnus crepidater, Dalatias licha, Deania calcea, Etmopterus pusillus, Etmopterus spinax, Galeus melastomus and Hexanchus griseus (Nunes 1994).
In Italy the main deep-water trawl fisheries target the red shrimps (Aristeus antennatus and Aristaeomorpha foliacea), the Norway lobster (Nephrops norvegicus) and hake. The only sharks that are marketed are the larger specimens of Galeus melastomus.