SCRS/2007/078 Collect. Vol. Sci. Pap. ICCAT, 62(5): 1483-1493 (2008)
AN OVERVIEW OF PELAGIC SHARK FISHERIES IN THE NORTHEAST ATLANTIC
Maurice Clarke1, Guzman Diez2, Jim Ellis3, Boris Frentzel-Beyme, Ivone Figueiredo, Kristin Helle, Graham Johnston, Mario Pinho, Bernard Seret, Helen Dobby, Nils-Roar Hariede, Henk Heessen, Dave Kulka and Charlott Stenberg
There is a long history of exploitation of pelagic sharks by European fisheries. Fisheries for basking shark (Cetorhinus maximus) and porbeagle (Lamna nasus) were well established in northern areas (e.g. off Norway) in the early 20th century. Although targeted fisheries for basking shark have now ceased, porbeagle is still taken in locally important directed fisheries in the Celtic Sea. Tuna and billfish fisheries, which expanded in recent decades, harvest shortfin mako (Isurus oxyrinchus), blue shark (Prionace glauca), and a variety of other pelagic sharks, with some of these fisheries targeting sharks at certain times/areas. Prior to the late 1990s, most European nations reported catches as “sharks not elsewhere identified”, and only in recent years has species-specific data become available. There is currently little biological sampling of commercial pelagic shark catches by fisheries laboratories, although there are some tag and release programmes for sharks. In recent years, the ICES Working Group on Elasmobranch Fishes has begun to collate available data on landings and from other data sources, and a brief overview of progress to date is given.
Il existe un long historique d’exploitation des requins pélagiques par les pêcheries européennes. Les pêcheries de requin pèlerin (Cetorhinus maximus) et de requin-taupe commun (Lamna nasus) étaient bien établies dans les zones septentrionales (au large de la Norvège, par exemple) au début du 20ème siècle. Même si les pêcheries dirigées sur le requin pèlerin ont désormais cessé d’opérer, le requin- taupe commun est encore capturé par les pêcheries dirigées dont l’activité locale est importante dans la mer celtique. Les pêcheries de thonidés et d’istiophoridés, qui ont connu une expansion au cours de ces dernières décennies, capturent le requin taupe bleue (Isurus oxyrinchus), le requin peau bleue (Prionace glauca) et divers autres requins pélagiques, et certaines de ces pêcheries ciblent les requins à certaines époques/dans certaines zones. Avant la fin des années 1990, la plupart des nations européennes déclarent des captures comme « requins non identifiés ailleurs », et ce n’est que récemment que les données spécifiques aux espèces sont devenues disponibles. Actuellement, les laboratoires halieutiques réalisent peu d’échantillonnage biologique des prises commerciales de requins pélagiques, bien qu’il existe des programmes de marquage-récupération pour les requins. Ces dernières années, le Groupe de travail sur les poissons élasmobranches de la CIEM a commencé à rassembler les données disponibles sur les débarquements et émanant d’autres sources de données, et une brève présentation des progrès réalisés jusqu’à ce jour est fournie.
Existe un largo historial de explotación de los tiburones pelágicos por parte de las pesquerías europeas. Las pesquerías de tiburón peregrino (Cetorhinus maximus) y marrajo sardinero (Lamna nasus) estaban bien establecidas en las zonas septentrionales (por ejemplo frente a Noruega) a comienzos del siglo XX. Aunque las pesquerías dirigidas al tiburón peregrino han cesado ya, el marrajo sardinero sigue siendo capturado en pesquerías dirigidas localmente importantes en el Mar Celta. Las pesquerías de túnidos e istiofóridos, que se ampliaron en décadas recientes, capturan marrajo dientuso (Isurus oxyrinchus), tintorera (Prionace glauca), y otros tiburones pelágicos, y algunas de estas pesquerías se dirigen a los tiburones en ciertas temporadas/zonas. Antes de finales de los 90, la mayoría de las naciones europeas
1 Marine Institute, Rinville, Oranmore, Co. Galway, Ireland. 2 Fundación AZTI, Instituto Tecnológico, Pesquero y Alimentario. Txatxarramendi ugartea z/g. 48395 Sukarrieta. Bizkaia. Basque Country (Spain). 3 Cefas Lowestoft Lab, Pakefield Road, Lowestoft, NR33 0HT, U.K. 1483 declaraba las capturas como “tiburones no identificados”, y únicamente en años recientes se ha dispuesto de datos específicos de cada especie. Actualmente existe poco muestreo biológico de las capturas comerciales de tiburones pelágicos por parte de los laboratorios pesqueros, aunque hay algunos programas de marcado y liberación para los tiburones. En años recientes, el Grupo de trabajo sobre Elasmobranquios de ICES ha empezado a recopilar los datos disponibles de los desembarques y de otras fuentes y se facilita un breve resumen del progreso alcanzado hasta la fecha.
1. ICES Working Group on Elasmobranch Fishes: A brief history
Following marked declines in the landings of spurdog and concerns about the status of other elasmobranchs, including various skates, ICES established a Study Group on Elasmobranch Fisheries, which first met in 1989. However, the work of this Study Group was restricted by the lack of appropriate data and could not conduct assessments. In 1995, the Study Group on Elasmobranch Fish (SGEF) was re-established and reported to the Living Resources Committee (LRC) of ICES. Initial reports (ICES, 1995-2001) focused on describing the fisheries and collating landings data and biological information, and attempts to carry out analytical assessments for some of the better-known demersal species (e.g. spurdog) was still hampered by the paucity of relevant data (ICES, 1999). Members of SGEF subsequently secured EU funding for a Concerted Action entitled “Preparation of a proposal for stock assessment of some elasmobranch fish in European waters” (FAIR CT98–4156), which was followed by a successful proposal for a three-year project entitled “Development of Elasmobranch Assessments (DELASS)”. The main objective of the DELASS project was “the improvement of the scientific basis for the management of fisheries taking elasmobranch species”. The DELASS project compiled available fisheries and biological data and undertook a variety of exploratory assessments in conjunction with SGEF (ICES, 2002; Heessen, 2003).
Because of the increased interest in elasmobranch fisheries at a European level, the need for ICES to provide regular advice, and the progress made under the DELASS project, SGEF changed to become the Working Group on Elasmobranch Fish (WGEF) in 2003 (ICES, 2003, 2004) and since 2005 has reported to ACFM (ICES, 2005, 2006). The ICES community has made progress in collating landings data, analysing survey data and in undertaking various exploratory assessments, primarily for demersal and deep-water elasmobranch stocks, and the recommendations from WGEF form the basis of advice that ACFM provides to the EC.
There are, however, several issues that still need to be addressed if robust assessments for elasmobranchs are to be undertaken, which include improved species-specific landings data, better life-history data, and biological sampling of commercial landings. Such data requirements are especially pertinent for pelagic fisheries. In terms of pelagic sharks, the DELASS project examined blue shark Prionace glauca as one of the nine case-study species, and recent reports of WGEF (ICES, 2006) have provided the information with which ACFM provided advice for basking shark Cetorhinus maximus and porbeagle Lamna nasus.
Although ICES assists in the provision of advice for fisheries operating in the NE Atlantic (Figure 1), the ICES area does not cover the northwestern Atlantic or Mediterranean Sea (even though large areas of the Mediterranean Sea are in EC waters). This is problematic for pelagic species, for which the stocks may occur throughout the North or NE Atlantic and extend into this area. To help redress this, two meetings of an elasmobranch subgroup were held by the EU’s Scientific, Technical and Economic Committee for Fisheries (STECF) to assist in the preparation of an EC Shark Action Plan. Although a considerable amount of background information for such a plan was provided, covering both the NE Atlantic and the Mediterranean (Anon., 2002, 2003), a formal Action Plan has yet to be prepared by the Commission.
2. Pelagic fisheries in the NE Atlantic and Mediterranean
2.1 Basking shark Cetorhinus maximus
The basking shark fisheries that once took place in the NE Atlantic have now ceased. The main fishery was prosecuted by Norway, using harpoons, with other fisheries (e.g. off Scotland and Ireland) ceasing earlier. Although the EC used to provide Norway with a quota for livers, this practice has now been discontinued, and there have been no targeted EC fisheries for basking shark in many years, although dead by-catch is landed occasionally in some areas. Overall, catches have declined from peaks in the 1960s and 1970s and ICES (2007) considered that available landings data and anecdotal information suggested that basking sharks were depleted, and advised that no targeted fishing for the species should be permitted and that additional measures should be
1484 taken to prevent their by-catch in fisheries targeting other species. Based on this advice, Norway banned all targeted fisheries for basking sharks.
WGEF has made progress in compiling landings data for this species, and in recent years there have been several studies on their movements and migrations (e.g. Southall et al., 2005) which suggest they are quite wide ranging in the NE Atlantic, which is consistent with the view of ICES that there is a single NE Atlantic stock.
2.2 Porbeagle Lamna nasus
The main countries currently targeting porbeagle in the NE Atlantic are France and Spain, with other nations having occasional small-scale fisheries targeting aggregations of porbeagle when they are locally abundant. There is a small, directed fishery operating from the Isle d’Yeu (France), and reported catches in this fishery have fluctuated between 300-1,000 t since the 1980s, with a slight overall decline. Landings off Spain tend to be greater during the spring and autumn, with a drop in the summer (Mejuto 1985; Lallemand-Lemoine 1991).
The history of the porbeagle fishery is well documented (e.g. in ICES, 2005, 2006). The following account is from Anon (2003);
“Porbeagle sharks are often taken as a by-catch in trawls, seines, pelagic and bottom gill nets and by surface longlines set for billfish and tunas. Traditional line fisheries directed at porbeagle (which also take occasional tope and blue sharks) in the northern North Sea and off the Scottish coast have involved specialised vessels from Norway and, to a lesser extent, Denmark and the UK, and French vessels fishing to the south and west of England. Prior to 1930, the Norwegian fleet used shark lines in the eastern North Sea, mainly during July-October. Over the period 1930-1965, Norway was the principal country fishing for porbeagle, and it extended the fishery to the Orkney- Shetland area and the Faeroes and then to the waters off Ireland and offshore banks by the 1950s. Landings by Norway first reached a peak of 3,884 t in 1933, and about 6,000 t were taken by the Norwegian fleet in 1947, when the fishery reopened after the Second World War. A progressive drop in Northeast Atlantic landings followed from 1953-1960, to around 1,200-1,900 t annually. In 1961, a fleet of Norwegian longliners extended their fishing for porbeagle to Northwest Atlantic waters off the coast of New England and Newfoundland. Catches of porbeagle had declined by 1965, when many of the vessels switched to other species or moved to West African grounds to fish for mako shark and swordfish (Gauld 1989). Norwegian landings from the Northeast Atlantic continued to decrease from 160-300 t/annum in the early 1970s to around 10-40 t/annum in the late 1980s/early 1990s.
Denmark’s small fleet of specialised shark longline vessels formerly operated in the summer months, predominantly in the North Sea but extending into the Northwest Atlantic in the 1980s (Gauld 1989). Average landings from the Danish porbeagle fishery fell from 500-600 t/annum in the 1950s to under 50 t in 1984. More recently, a minimum of 32 t was landed by Denmark in 1988, rising to 94 t in 1994 (ICES 1995). Porbeagles were reported in landings statistics by Scotland in the mid to late 1950s (Rae 1962; Gauld 1989). The Faeroes, France, England, Iceland, Germany and Sweden started landing significant quantities in the 1970s. French longliners have operated a directed fishery for porbeagle from Isle d’ Yeu, landing into La Rochelle (Lallemand-Lemoine 1991). The main fishing grounds were in the Celtic Sea and Bay of Biscay from where over 77% of the total French catch of 640 t recorded by all gears in 1993 was landed. Their activity is now decreasing. Similarly, local fisheries in the Bristol Channel occasionally deploy longlines for porbeagle (Ellis & Shackley, 1995).
Porbeagle are currently landed by many European countries, principally Denmark, the Faeroes, France, Norway and Spain. Smaller quantities are landed by the Channel Islands, Iceland, Portugal, Sweden, Germany, Ireland and the United Kingdom. According to the FAO Yearbook of fisheries statistics, porbeagle landings in 1994 by all countries fishing the Northeast Atlantic totalled 985 t, of which Norway landed only 25 t. Annual landings during the period 1995-1999 have been in the range of 400-700 t.”
Although catch data are incomplete and there are few ancillary data (e.g. no fishery-independent data, and little or no biological sampling of caches), ICES (2007) considered that because the fisheries in northern waters had not resumed, the stock of porbeagle in these areas has probably not recovered. Moreover, catch per unit effort (cpue) in the French fishery has declined since the mid-1990s (ICES, 2006). Based on this, ICES (2007) advised that there should be no targeted fisheries for porbeagle and that measures should be taken to mitigate by-catch in other fisheries. These views were also supported by a meeting of STECF. For 2007, the European Commission set a TAC of 174 t for porbeagle in the NE Atlantic.
1485 Although WGEF have made progress in compiling landings data, these data are incomplete, due to some nations not reporting catches of sharks in some years/periods, and also by the use of generic landings categories. Data for some of the northern European countries (e.g. Norway and Denmark) have been reported consistently, with other nations having improved species-specific data in recent years, and have had period of time reporting landings as “sharks” (e.g. UK). French landings have been reported annually, though there may be small discrepancies in their national reported landings, which are sometimes less than those subsequently reported for the Isle d’Yeu fishery (Table 1). Some smaller vessels (<10 m) do not always report landings data, and it is unclear as whether data from the Isle d’Yeu fishery are included in national landing statistics. Within the EC, smaller vessels have not always had to report their landings, and given that France and other countries (including UK) have some small vessels targeting porbeagle, it is likely that official landings are less than actually harvested. Spain report large quantities of porbeagle in occasional years, though data are not reported consistently, although species species specific records in landings have improved in the last few years. Portuguese fisheries have occasional by-catch of porbeagle, both off the mainland and the Azores, although targeted fisheries are not known to exist.
2.3 Blue shark Prionace glauca
The following account of blue shark fisheries is taken from Anon (2003):
“Blue shark is taken mainly as a by-catch in surface longline fisheries for tuna and billfish by Spanish fishermen as far south as the west coast of Africa. This fishery has developed rapidly since the 1940s and it is estimated that 2,400 t of blue shark were taken in 1984, up to 82% of which were discarded due to their low value compared to that of swordfish Xiphias gladius or even mako and porbeagle sharks (Vas, 1995; Mejuto, 1985). During 1997 and 1998, the total landings of pelagic sharks from the swordfish fishery had risen to 35,000 t and 32,700 t respectively, with 85% of the landings comprising blue shark and 10% shortfin mako (Castro et al., 2000). The remainder includes diverse species of Carcharhinus spp., Alopias spp. and others. In 1999, the by-catch landings of blue shark from the North Atlantic had fallen to 21,811 t (89% of total pelagic sharks) (Mejuto et al., 2002). Both mainland Portugal and the Azores also have longline fisheries for tuna, which take a by-catch of blue sharks. In Mainland Portugal, landings from ICES Sub-area IXa have fluctuated between 340 and 540 t during the 1990s.
Further north, blue sharks are taken by swordfish longline vessels operating from northern Spain (Mejuto, 1985), and a small Spanish longline fishery targets blue shark mainly between June and November in the Bay of Biscay (VIII) (Lucio et al., 2002). In addition, France, UK and Ireland have had gillnet fisheries for albacore tuna Thunnus alalunga beyond the slope of the continental shelf, in which blue sharks are taken as a by-catch. Other pelagic sharks taken in the same fisheries are the mako, hammerhead (Sphyrnidae) and bigeye thresher Alopias superciliosus. Given the increasing commercial value of these species, it is assumed that discards of blue shark are decreasing whilst those of shortfin mako are negligible.
In the summer months, blue sharks move north to cooler waters as far as the south coast of England and southern, western and northern coasts of Ireland. They have been the target of recreational anglers from ports in south-west England since the early 1950s, though the catches taken by this fishery have fallen considerably since 1960 (Vas, 1990). In the UK, a small-scale longline fishery for blue and porbeagle sharks was started off the south coast of Cornwall in 1990. In 1992, vessels registered in England and Wales accounted for 757 t of shark, of which half were landed abroad. The equivalent landings by the 6 boats fishing for sharks in 1994 was 893 t, in a fishery which now appears to take place mainly off the shelf edge in the Celtic Sea and west of Ireland. In Irish waters blue sharks are targeted by anglers in a tag and release fishery (Fitzmaurice and Green, 2000). Since its inception in 1970, this tagging programme has resulted in the release of sharks (Fitzmaurice et al., 2003).
Apart from the European fisheries described above, the most important source of mortality on blue sharks probably arises where they are taken as a by-catch in the high seas longline and driftnet fleets targeting tuna and billfish from the nations Japan, Taiwan, Korea and Russia. These fisheries operate throughout the blue shark's geographical range, including the Mediterranean (De Metrio et al., 1984). There is usually no requirement for these fisheries to record their blue shark catch and, because the entire catch is not retained on all fishing trips, the available landing data might not be indicative of stock trends. Due to the increasing price paid for shark fins, however, it is becoming less clear whether the blue (and other pelagic) shark is the target or by-catch species in these fisheries.”
1486 WGEF attempts to assemble landings data for North Atlantic blue shark has been severely restricted by the lack of species-specific landings data, particularly from some of the more important shark fishing nations (e.g. Spain). Estimating removals for blue shark will be problematic, given the spatial and temporal differences that could affect the proportions discarded or retained.
2.4 Mako shark Isurus oxyrinchus
Only recently has WGEF attempted to assemble landings data for mako shark (ICES, 2006), and although there are limited species-specific data, a major part of the landings were not available at the species level and further studies are ongoing.
2.5 Thresher sharks Alopias vulpinus
Two species of thresher shark occur in the ICES area, with A. vulpinus more likely to occur in more coastal and northern parts of the ICES area, and A. superciliosus occurring further offshore. Several studies have provided anecdotal information regarding the presence of juveniles in coastal waters and potential nursery grounds (refs). WGEF has not dealt with thresher sharks to date, although hope to start collating data in 2007.
3. National fisheries
Iceland: Icelandic captures of porbeagle in ICES Division are about 1-5 tonnes.y-1. Iceland has some sporadic large pelagic fisheries, and report landings of bluefin tuna and swordfish in occasional years.
Faeroe Islands: Faeroese fisheries regularly report landings of porbeagle, with annual landings usually in the order of 5-25 t.y-1. Larger catches (44-76 t.y-1) were reported in 1993-1995. Most of these landings are around the Faeroe Islands (ICES Division Vb), although they are also reported from adjacent areas (IIa, IVa, VIb etc.)
Norway: Norwegian landings of porbeagle were high in the 1970s (up to 300 t.y-1), though have been lower since, usually amounting to 20-30 t.y-1 since the 1990s. Most landings are from ICES Divisions IIa, IVa and IIIa.
Sweden: Sweden have regularly reported landings of porbeagle from ICES sub-areas II-IV, with annual landings usually < 5 tonnes, although 9-10 tonnes were taken in 1984-85.
Denmark: Danish landings of porbeagle were in the region of 100-300 t.y-1 for most of the 1970s, with more recent landings generally < 100 t.y-1. Since 2003, reported landings have been about 20 t.y-1.
Germany: Nominal porbeagle landings are available for 1973-1975 and from 2000 onwards, although are usually < 5t.y-1. The absence of porbeagle in landing statistics between these times would suggest that porbeagle are also a component of the ‘various sharks nei’ landings and further examination of German landings are therefore required.
Belgium: Most of Belgium’s fisheries are demersal, with landings of ‘skates and rays’ and spurdog reported. There are reported landings of ‘various sharks nei’ (11-25 tonnes.y-1) since 1989, mostly from ICES Division IVc, and so likely comprise smooth-hounds and tope, although thresher sharks and porbeagle can occur in this area.
The Netherlands: Large sharks are not usually reported in Dutch landings data, although porbeagle and thresher shark are likely to be taken as occasional by-catch
United Kingdom: Landings data for the UK (England, Wales, Scotland and Northern Ireland) as well as various surrounding islands (Channel Islands and Isle of Man) are relatively difficult to interpret. Species-specific data for porbeagle were reported in the early 1970s (13-21 t.y-1) and also since 2000 (8-27 t.y-1). Between these periods landings of ‘various sharks nei’ gradually increased. Many of these landings are from ICES divisions along the western seaboard and it is unclear as to whether they refer to porbeagle, blue shark or other shark species. Further examination of UK landings data are therefore required. Since 2000, UK has also reported 4-12 t.y-1 of blue shark and small quantities of mako (<2 t.y-1) and thresher (unreported) may be taken.
1487 In addition to fisheries in the ICES areas, Anglo-Spanish vessels operate in the central and South Atlantic and parts of the Indian Ocean, and various UK Overseas Territories may also have fisheries taking pelagic sharks. Some of these vessels have 100% observer coverage for some of those vessels while other vessels supply EU logbooks that report blue and short fin mako sharks separately. Although the catches from those vessels are small, analysis of these data might provide some information on number of sharks taken relative to the number of targeted species caught.
The Shark Angling Club of Great Britain have some data on recreational catches of blue shark (and other species) from the south-west of the UK, and there have been some tagging experiments (Stevens, UK Shark Tagging). Although there are no formal biological studies programmes at the fisheries laboratories, some ad hoc data on size compositions of commercial catches have been made, although such data are limited.
Ireland: Pelagic fisheries expanded in the 1990s, with various tunas and swordfish reported on a regular basis. Landings of blue shark and porbeagle have been reported since 1999, with usually <10-20 t.y-1 of porbeagle taken. Small numbers of ‘mackerel sharks’ and thresher shark are also reported. Landings of ‘various sharks nei’ since 1993, though the use of this category has declined in recent years.
The Irish Central Fisheries Board conducts two research programmes of relevance to pelagic sharks. The data associated with these programmes are described in a separate working document (Green et al. 2007). Pelagic sharks have been tagged and released as part of an ongoing programme since 1970. From 1970 to 2005, 17,562 blue sharks were tagged, with a recapture rate of 773 (4.4%). In that period 71 porbeagles were tagged, with 7 recaptures (9.85%). These data are being archived and collated as part of a new project, in collaboration with the Irish Marine Institute. Preliminary analyses were carried out and presented to ICCAT (Fitzmaurice et al. 2004).
Catch-per-unit-effort data for blue shark has been collected in a sea-anglers logbook scheme, in the Irish recreational fishery, since 1978. Catch and effort data are available from a series of angling centres around the Irish coast. A refined data series, representing 10 centres, with relatively consistent operating procedures, was developed for the years 1989 to present. Preliminary results are presented in Green et al. (2007). Further work on identifying suitable categorical variables and GLM standardisation of the series is planned, in anticipation of the ICCAT shark stock assessment meeting in 2008.
France: France has fisheries for various large pelagics, especially tunas, and these have a shark by-catch. There are also some targeted shark fisheries (e.g. for porbeagle). Reported landings of porbeagle were >1,000 in 1979 and have been usually <500 t.y-1 since the mid-1990s. Reported landings of blue shark increased during the 1980s, with 100-400 t.y-1 reported since the 1990s. Catches of thresher shark were also generally low prior to the early 1990s, but have since been approximately 10-20 t.y-1, although they peaked at >100 t.y-1 in 2000-01. France had large quantities of landings allocated to ‘cartilaginous fishes nei’ in the 1970s, although the use of generic landings categories has been reduced since the 1980s. France also has important pelagic fisheries elsewhere in the Atlantic and Indian Oceans.
Spain: Spanish pelagic fisheries take large quantities of sharks. Although there have been improvements in the reporting of species specific data (e.g. smooth and scalloped hammerheads, thresher sharks, shortfin mako, requiem sharks and blue shark) since 2004, there was widespread use of more generic categories (including ‘cartilaginous fishes nei’ and ‘various sharks nei’). Indeed, the combined total of reported landings of these generic categories between 1990 and 2003 was 227,510 tonnes. Given the magnitude of these landings, improved data prior to 2004 are required. The data on the catches of the directed long line Basque fishery for the period 1998-2006 are available. Catches of that fishery fluctuated from approximately 70 t to 359 t in that period (Diez et al. 2007).
Portugal: Portuguese fisheries target a variety of large pelagic fishes, and reported landings of sharks up until 1999 were mostly reported as ‘cartilaginous fishes nei’ or ‘various sharks nei’. There have been improved species-specific data since 1999, with blue sharks the most abundant species taken (1000-2000 t.y-1), followed by shortfin mako (100-600 t.y-1), requiem sharks (10-145 t.y-1), thresher sharks (13-80 t.y-1) and hammerheads (<10 t.y-1).
Although outside the ICES area, various EC fleets also operate in the Mediterranean Sea. There are no large- scale commercial fisheries targeting migratory, oceanic sharks in the Mediterranean Sea, although fisheries do target large pelagic fishes (e.g. swordfish, bluefin tuna and albacore) with longlines and drift nets, and these
1488 fisheries have a by-catch of pelagic sharks. Several types of longline are used in Mediterranean fisheries, including swordfish longlines, American-type swordfish longlines, and longline targeting albacore and bluefin tuna. Drift nets were used (mainly by Italian vessels), until the EC ban in January 2001.
Given the lack of information on shark by-catch in Mediterranean pelagic fisheries an EC-funded project (No. 97/50 DG XIV/C1) examined the by-catch and discards in Greek, Italian and Spanish fleets fishing for swordfish and tunas in 1998-1999 (see Anon, 2003). At least 10 species of pelagic shark are taken incidentally in Mediterranean pelagic fisheries which are, in order of importance: blue shark Prionace glauca, shortfin mako Isurus oxyrinchus, common thresher shark Alopias vulpinus, porbeagle Lamna nasus, tope Galeorhinus galeus, bigeye thresher shark Alopias superciliosus, sandbar shark Carcharinus plumbeus, basking shark Cetorhinus maximus, sixgill shark Hexanchus grisues and smooth hammerhead Sphyrna zygaena (see Anon, 2003).
The catch composition of sharks caught in those parts of the Mediterranean Sea studied, showed that 68 and 82% (by weight) comprised blue shark in 1998 and in 1999 respectively (Anon, 2003). Most sharks were caught in the swordfish fishery, and lowest numbers were taken in the albacore longline fishery. Further information on the Mediterranean fisheries is given in Anon (2003) and references cited therein.
Data on pelagic sharks taken in North African fisheries are poorly described and further studies on these fisheries are required.
ANON. (2002) Report of the subgroup on resource status (SGRST) of the Scientific, Technical and Economic for Fisheries (STECF): Elasmobranch Fisheries, Brussels, 23–26 September 2002, 102 pp. ANON. (2003a) Report of the subgroup on resource status (SGRST) of the Scientific, Technical and Economic for Fisheries (STECF): Elasmobranch Fisheries, Brussels, 22–25 July 2003. CASTRO, J., J.M. de la Serna, D. Macias, and J. Mejuto (2000). Preliminary scientific estimates of by-catch landings by the Spanish surface longline fleet in 1997 and 1998. (SCRS/99/082). ICCAT. Collect. Sci. Pap. vol. 51, no. 1, pp. 1882-1894. DE METRIO, G., Petrosino, G., Montanaro, C., Matarrese, A., Lenti, M. and Cecere, E. (1984). Survey on summer-autumn population of Prionace glauca L. (Pisces, Chondrichthyes) in the Gulf of Taranto (Italy) during the four year period 1978-1981 and its incidence on sword-fish (Xiphias gladius L.) and albacore (Thunnus alalunga (Bonn)) fishing. Oebalia, 10: 105-116. DÍEZ1 G., Santurtún, M., Ruiz, J., Iriondo, A., Gonzalez. I., & Artetxe, I. 2007. The long line Basque fishery on blue shark (Prionace glauca) in the Bay of Biscay (1998-2006). Working Document for the ICES Working Group on Elasmobrach Fishes, Galway 22-28 June, 2007. ELIS, J.R. & S.E. Shackley (1995). Notes on porbeagle sharks, Lamna nasus, from the Bristol Channel. J. Fish. Biol., 46: 368-370. FITZMAURICE, P. and Green, P. (2000). Results from tagging of blue sharks in Irish waters. Irish Scientist Yearbook, 3:51. FITZMAURICE, P., Green, P Kierse, G., Kenny, M and Clarke, M. 2004. Stock discrimination of the blue shark based on Irish tagging data. SCRS Document. SCRS/2004/123. FITZMAURICE, P., G. Keirse, P. Green, M. Clarke, and M. Kenny. 2003. Results from the tagging (1970-2001) and Catch per unit effort (1978-2002) of blue shark (Prionace glauca) in Irish waters from the marine sport fishery. Central Fisheries Board. Unpublished Report. GAULD, J.A. (1989). Recordings of porbeagles landed in Scotland, with observations on the biology, distribution and exploitation of the species. Scottish Fisheries Research Report No. 45. DAFS, Edinburgh: 1-13. GREEN, P., Roche, W., Fitzmaurice, P., Clarke, M., Kierse, G., Kenny, M. 2007. Data on blue shark from the Irish recreational fishery. Working Document to ICCAT Pelagic Shark Data Preparatory Meeting. SCRS/2007/101 HEESSEN, H. J. L. (ed) (2003) Development of Elasmobranch Assessments – DELASS: DG Fish Study Contract 99/055.
1489 ICES (1989) Report of the Study Group on Elasmobranch Fisheries. 26–28 April 1989, Dublin, Ireland. ICES Document CM 1989/G: 54, 37 pp. ICES (1995) Report of the Study Group on Elasmobranch Fishes. 15–18 August 1995, Copenhagen, Denmark. ICES Document CM 1995/G: 03, 88 pp. ICES (1996) Report by Correspondence of the Study Group on Elasmobranch Fishes. ICES Document CM 1996/G: 04, 49 pp. ICES (1997) Report of the Study Group on Elasmobranch Fishes. 26–30 May 1997, Copenhagen, Denmark. ICES Document CM 1997/G: 02, 123 pp. ICES (1998) Report of the Study Group on Elasmobranch Fishes. ICES Document CM 1998/G: 12, 29 pp. ICES (1999) Report of the Study Group on Elasmobranch Fishes. 23–27 March 1999, Santander, Spain. ICES Document CM 1999/G: 11, 18 pp. ICES (2000) Report of the Study Group on Elasmobranch Fishes. ICES Document CM 2000/G: 09, 9 pp. ICES (2001) Report of the Study Group on Elasmobranch Fishes. ICES Document CM 2001/G: 07, 6 pp. ICES (2002) Report of the Study Group on Elasmobranch Fishes, 6-10 May 2002, Copenhagen, Denmark. ICES Document CM 2002/G: 08, 119 pp. ICES (2003) Report of the Working Group on Elasmobranch Fishes, 28 April-2 May 2003, Vigo, Spain. ICES Document CM 2003/G: 09, 151 pp. ICES (2004) Report of the Working Group on Elasmobranch Fishes (WGEF). ICES Document CM 2004/G: 11, 110 pp. ICES (2005) Report of the Working Group on Elasmobranch Fishes (WGEF). 14-21 June 2005, Lisbon, Portugal. ICES Document CM 2006/ACFM: 03, 229 pp. ICES (2006) Report of the Working Group on Elasmobranch Fishes (WGEF). 14-21 June 2006, ICES Headquarters. ICES Document CM 2006/ACFM: 31, 299 pp. LALLEMAND-LEMoine, L. (1991). Analysis of the French fishery for porbeagle Lamma nasus (Bonnaterre, 1788). ICES-CM-1991/G:71, 10 pp. LUCIO, P., V. Ortiz de Zárate, G. Díez, C. Rodríguez-Cabello, and M. Santurtún (2002). Description of an experimental artisanal fishery targeting blue shark in the Bay of Biscay, 1998 - 2000. NAFO Symposium on Elasmobranch Fisheries. Santiago de Compostela (Spain), 11-13 September 2002. MEJUTO, J. (1985). Associated catches of sharks, Prionace glauca, Isurus oxyrinchus and Lamna nasus, with NW and N Spanish swordfish fishery in 1984. ICES C.M. 1985/H:42: 16pp. MEJUTO, J., B. García-Cortés and J.M. de la Serna, (2002). Preliminary scientific estimations of by-catches landed by the Spanish surface longline fleet in 1999 in the Atlantic Ocean and Mediterranean Sea. ICCAT, SCRS/01/049. Collect. Vol. Sci. Pap. ICCAT, 54(4): 1150-1163. RAE, B.B. (1962). Porbeagle sharks. Scottish Fisheries Bulletin, 18: 17-19. SOUTHALL, E.J., Sims, D.W., Metcalfe, J.D., Doyle, J.I., Fanshawe, S., Lacey, C., Shrimpton, J., Solandt, J-L and Speedie, C.D. (2005). Spatial distribution patterns of basking sharks on the European shelf: preliminary comparision of satellite-tag geolocation, survey and public sightings data. Journal of the Marine Biological Association of the United Kingdom, 85, 1083-1088. VAS, P. 1990. The abundance of the blue shark, Prionace glauca, in the western English Channel. Environmental Biology of Fishes. 29: 209-225. VAS, P. (1995). The status and conservation of sharks in Britain. Aquatic Conservation: Marine and Freshwater Ecosystems, 5: 67-79.
1490 Table 1. Reported French landings of porbeagle as supplied to ICES and as reported recently from sales slips (mostly originating from the Isle d’Yeu fishery). Data source: ICES (2006).
Isle d’Yeu (as proportion of Year France1 Isle d’Yeu2 total landings) 1990 551 575 1.04 1991 294 305 1.04 1992 496 462 0.93 1993 633 642 1.01 1994 812 816 1.01 1995 565 643 1.14 1996 267 475 1.78 1997 331 494 1.49 1998 219 419 1.91 1999 237 371 1.57 2000 319 354 1.11 2001 237 367 1.55 2002 353 448 1.27 2003 258 434 1.68 2004 251 377 1.50 2005 221 301 1.36 1 From Table 6.2 of ICES (2006); 2 From Table 6.3 of ICES (2006)
Figure 1. ICES fishing areas,
1492 Pelagic and large coastal elasmobranchs in the CLOFNAM area (from Whitehead et al. 1984).
Family Common name Scientific name Lamnidae White shark Carcharodon carcharias Shortfin mako Isurus oxyrinchus Longfin mako Isurus paucus Porbeagle Lamna nasus Alopiidae Thresher shark Alopias vulpinus Bigeye thresher Alopias superciliosus Cetorhinidae Basking shark Cetorhinus maximus Triakidae Tope Galeorhinus galeus Carcharhinidae Spinner shark Carcharhinus brevipinna Silky shark Carcharhinus falciformis Blacktip shark Carcharhinus limbatus Oceanic whitetip Carcharhinus longimanus Dusky shark Carcharhinus obscurus Sandbar shark Carcharhinus plumbeus Night shark Carcharhinus signatus ? Tiger shark Galeocerdo cuvier Blue shark Prionace glauca Sphyrnidae Scalloped hammerhead Sphyrna lewini Great hammerhead Sphyrna mokkaran Smooth hammerhead Sphyrna zygaena Dasyatidae Pelagic stingray Pleuroplatytrygon violacea Mobulidae Devil ray Mobula mobula