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14 may 1999
11TH CITES CONFERENCE: UK PROPOSAL TO LIST THE BASKING SHARK ON APPENDIX II
Please find enclosed a United Kingdom proposal to add the Basking Shark (Cetorhinus maximus) to Appendix II of the Convention at the next meeting of the Conference of the Parties in Gigiri in April 2000.
Because of the large number of range states for this species, we are asking the Secretariat to circulate the proposal to Parties in accordance with the procedures set down in Resolution Conf. 8.21.
Attached to the proposal itself is an executive summary which picks out the key points of the case for an Appendix II listing, namely:
- the Basking Shark is listed as Vulnerable in the IUCN Red List
- It is slow to mature, long-lived, with a low fecundity and long gestation period. This, together with its ease of capture, make it particularly vulnerable to over exploitation
- Rapid declines have been recorded from targeted fisheries
- Its fins, which are readily recognisable, are increasingly valuable in international trade
- It is listed in the FAO plan as one of 20 sharks most vulnerable to over-fishing.
We conclude that:
- a decline in the number of individuals in the wild has been observed as ongoing;
- harvesting specimens from the wild for international trade may not be sustainable in the long term; and
- unless trade is subject to strict regulation, the species is likely to further decline.
We look forward to hearing the results of the Secretariat's full consultation process.
J P CLAXTON
Proposal to include the Basking Shark (Cetorhinus maximus) on Appendix II of the Convention on International Trade in Endangered Species (CITES)
- The Basking Shark (Cetorhinus maximus) is widely distributed in coastal waters and on the continental shelves of temperate zones in the northern and southern hemispheres. The species is planktivorous, bears a small number of live young (ovoviviparous) and is the second largest fish in the world (up to 10m in length and 5-7t in weight), exceeded only by the whale shark Rhincodon typus.
- C. maximus is considered to be Vulnerable in the 1996 IUCN Red List based on past records of declining populations, due to exploitation by fisheries, slow recovery rates and the potential for similar declines to occur in future due to targeted and by-catch fisheries.
- The biology of the species makes it especially vulnerable to exploitation; it is extremely K-selected even for a shark. It has a slow growth rate, a long time to sexual maturity (c. 12-20 years), a long gestation period (1-3 years) and a similar interval between pregnancies, low fecundity (the only recorded litter was of just six very large pups), and probable small populations. However, the species is poorly studied and many aspects of its life history remain to be elucidated. Its habit of 'basking' at the surface makes it vulnerable to harpoon fisheries.
- There are a few well-documented fisheries for C. maximus (especially from the NE Atlantic) and these suggest stock reductions of 50-90% over short periods (typically a few decades or less). These declines have persisted into the long-term with no apparent recovery several decades after exploitation has ceased. Other data, based on sightings and less well-recorded fisheries, suggest similar declines. Factors other than exploitation, such as food supply and oceanographic changes, also need to be taken into account.
- Traditionally, basking sharks have been hunted for their liver which yields an oil rich in squalene. This market is now largely superseded but demand for the fins of C. maximus has increased. Fins are known to enter international trade, particularly from the NE Atlantic to eastern Asia where they command a high value, either fresh or dried, as a food item. This demand currently maintains the viability of targeted fisheries for this species and encourages incidental take in non-target fisheries. A single C. maximus can yield over 90kg of fins and reported prices range from 100-300$/kg (dried) and $26/kg (fresh). Whole fins are reported for sale at over $6000. Fins, if unprocessed, are identifiable in trade. There is only limited demand for the flesh and cartilage of this shark.
- This species meets the criteria listed in Conference Resolution 9.24, Annex 2a, Bi, namely that 'it is known, inferred and projected that harvesting of specimens from the wild for international trade has, or may have, a detrimental impact on the species by exceeding, over an extended period, the level that can be continued in perpetuity'. The species also meets criterion in Annex 1, Ci & ii, namely that 'a decline has been either observed as ongoing or as having occurred in the past, and is inferred and projected on the basis of levels or patterns of exploitation'.
The species is only given protection over a limited part of its range (including Great Britain) and no fisheries are properly managed. This proposal is intended to help ensure that exploitation of this globally threatened species is regulated and monitored, and that international trade is not detrimental to the survival of the species. Due to the inevitable gaps in information for such a poorly studied fish, application of the precautionary principle (as defined in Resolution 9.24) is necessary. Listing on Appendix II will help to implement, in part, the FAO International Plan of Action for the Conservation and Management of Sharks, recently agreed in Rome. It may also encourage fisheries management and research into this species, where it is presently lacking, to ensure the long-term sustainability of harvests.
Proposal to include the Basking Shark (Cetorhinus maximus) on Appendix II of the Convention on International Trade in Endangered Species (CITES)
Inclusion of the Basking Shark (Cetorhinus maximus) on Appendix II of CITES.
United Kingdom of Great Britain and Northern Ireland
Chondrichthyes (subclass Elasmobranchii)
Cetorhinus maximus (Gunnerus, 1765)
Halsydrus pontoppidani (Neill, 1809); Tetroras angiova Rafinesque, 1809; Squalus gunnerianus Blainville, 1810; Squalus homianus Blainville 1810; Squalus pelegrinus Blainville, 1810; Squalus peregrinus Blainville, 1811; Squalus (Cetorhinus) gunneri Blainville, 1816; Squalus (Cetorhinus) shavianus Blainville, 1816; ? Scoliophis atlanticus Anon., 1817; Squalus isodus Macri, 1819; Squalus rostratus Macri, 1819; Squalus elephas LeSueur, 1822; Squalus rashleighanus Couch, 1838; Squalus rhinoceros Mitchell, in DeKey, 1842; Squalus cetaceus Gronow, 1854; Polyprosopus macer Couch, 1962; Cetorhinus blainvillei Brito Capello, 1870; Selachus pennantii Cornish, 1885; Cetorhinus maccoyi Barrett, 1933; Cetorhinus maximus forma infanuncula Deinse & Adriani, 1953; Cetorhinus maximus normani Siccardi, 1960.
English:Basking shark, (traditionally sunfish or sailfish, hoe mother)
Cearban (Scotland), liabhán mór, liabhán chor gréine (Ireland)
Temperate waters of continental and insular shelves, very occasionally recorded well offshore in oceanic waters but most commonly seen very close to the coast. They are not recorded from the tropics, and records from the warmest areas are often of dead, stranded or moribund specimens. They may occur in boreal waters during the summer. Although widely distributed, they are generally infrequently recorded except in a few apparently favoured coastal areas, where they are usually seen in relatively large numbers for only part of the year.
Their north Atlantic distribution extends from the transition between Atlantic and Arctic waters (including Newfoundland (Canada), the Gulf of Maine (USA), south and west of Iceland, off the North Cape of Norway and in the western Barents Sea and White Sea), to the Mediterranean (at least as far east as Turkey) and as far south as Senegal (possibly only as dead, stranded specimens) and Florida, USA (including moribund specimens at the southern edge of their range).
In the south Atlantic they are recorded from southern Brazil to Argentina and off the west and south coast of Cape Province, South Africa. In the northwest Pacific, they are recorded from Japan to the Koreas and China, in the northeast Pacific from the Gulf of Alaska, through British Columbia to Gulf of California, and in the southeast Pacific off Ecuador, Peru and Chile. In Australasia, they are only rarely recorded from Australia (New South Wales, Victoria, Tasmania, south and southwestern Australia) but they are more common in cooler New Zealand waters. (Compagno 1984, Last & Stevens 1994).
Major north Atlantic range states include Norway, Sweden, the United Kingdom, Ireland, France, Spain, Portugal, Italy, Greece and Turkey in Europe; the USA and Canada (northwest Atlantic and also Northeast Pacific). Other range states in the North Atlantic include the other Mediterranean countries (possibly excluding the extreme east and southeast), Iceland, Faeroes, Denmark, Russian Federation, and possibly northwest African states.
Elsewhere, major range states include Japan, the Republic of Korea, the Democratic People's Republic of Korea, and China in East Asia; Brazil, Argentina, Uruguay, Ecuador, Chile and Peru in South America; South Africa and New Zealand.
Distribution records are characterised by highly seasonal appearances, and the species may be highly migratory, although no long-distance tracking of individuals has been reported. The majority of basking shark records in UK waters appear to be correlated with a narrow range of water temperatures: 8°-14°C, 14°C in Japan, or 8-12°C in Newfoundland (Lien and Fawcett 1986). Owen (1984), however, reported sightings off the New England northwest Atlantic coast ranging from sea surface temperatures of 11°-24°C, with most sightings at surface temperatures of 16°-24°C, and peak densities at 22°-24°C.
Records in higher latitudes are most common during the spring and summer months, suggesting a seasonal migration occurs. This migration may take place from deep to shallow water (indicated by high levels of squalene in liver oil in spring, followed by increasing levels of vitamin A later in the year) or from lower to higher latitudes as sea temperatures rise, or both. In the North Atlantic, basking sharks appear in the southern part of their range in spring, more northern areas in summer, then apparently almost disappear in autumn and winter. Owen (1984) reports that basking sharks are first sighted by aerial surveys in the spring over very deep water along the southern and eastern margins of Georges Bank, off New England (USA). They move into shallow shelf waters as the season progresses, particularly after the thermocline has developed and zooplankton densities are at their height.
In the eastern North Pacific, basking sharks are recorded in largest numbers in winter (November to March) on the Californian coast, and occur in northern latitudes (Washington and British Columbia) in the spring and summer (Compagno, 1984). In the western North Pacific, the Japanese basking shark fishing season off the Shima Peninsula, Mie Prefecture, was also in spring and early summer (March to May).
There is a pronounced spatial and seasonal population segregation, with groups of animals of similar sizes and the same sex often sighted together. Most basking sharks caught in surface fisheries in Scottish waters were recently mated females (F:M ratio of 18:1, Watkins 1958), and 65-70% of sharks taken in Japan were also female. Conversely, catches in sub-surface gill nets off Newfoundland included twice as many male as female sharks (Lien & Fawcett 1986). Despite the large numbers of mature females taken in fisheries, there is only one known record of a pregnant female (with a litter of six). Newborns and juveniles are also only rarely seen, indicating that their populations occur elsewhere, out of the range of surface fisheries.
Basking shark numbers (or recorded sightings) in some regions appear to vary over an indeterminate time scale. For example, exceptionally large numbers of basking sharks were sighted in Brittany, France and southwest England in 1998 (Speedie 1998), but apparently not in other areas of the UK. Similar 'invasions' have been reported elsewhere from time to time (Kunzlik 1988, Castro et al. in preparation). However, superimposed on this pattern is one of individual sharks being re-sighted repeatedly at certain locations year after year (Watterson in lit., Compagno in lit.).
Tagging programmes using satellite transmitters and other electronic tags are proposed in a number of locations. If successful, these should help to elucidate the migratory routes of these sharks.
Siccardi (1960, 1971) suggested that there are four species of Cetorhinus, two in the North Atlantic and Mediterranean (C. maximus and C. rostratus), one from southern Australia (C. maccoyi), and one from the South Atlantic (C. normani). Compagno (1984) and Springer and Gilbert (1976) consider there is insufficient evidence to separate these species. Tomás and Gomes (1989) describe some morphological dissimilarities between basking sharks caught in gill net fisheries off Southeastern and southern Brazil and those described from the North Atlantic. These observations may indicate that little or no exchange takes place between northern and southern hemisphere populations by migration in deep cold waters below the thermocline. No research has addressed the question of whether genetically distinct sub-populations exist in different oceans or hemispheres. Some tissue sampling is now taking place and the DNA studies planned may eventually help to clarify the status of various populations.
2.2 Habitat availability
Habitat availability is not considered to be a constraint for this species.
Basking sharks are mainly recorded from temperate coastal, inshore and oceanic waters, reported from surface sightings when the sharks are feeding or congregating at or very close to the surface. Surface waters preferred for feeding and possibly mating activity appear to be ocean fronts, or close inshore off headlands and islands and in bays where 'tide lines' are formed in areas of strong tidal flow and zooplankton aggregate (Earll 1990, Sims et al. 1997, Sims and Quayle 1998).
Basking sharks are also taken occasionally in temperate oceanic drift nets and as by-catch in shallow and deep-set nets in coastal areas. Bonfil (1994) uses observer data to extrapolate to a figure of some 50 basking sharks taken annually in the whole of the Pacific oceanic drift net fisheries, suggesting that only small numbers are found away from the coast. The species is thought to over-winter in deep water offshore, but the location of such wintering grounds is generally unknown. Only a few winter records have been reported, including sharks caught in deep water trawls in the Gulf of St Lawrence, Newfoundland, Canada (Lien and Aldrich 1982) and the Firth of Clyde, Scotland (Fairfax 1998). Owen (1984) describes how the first sharks sighted on or near the surface in spring are over deep water on the edge of Georges Bank, off New England, USA.
2.3 Population status
The global status of the basking shark is assessed as Vulnerable (A1a,d, A2d) in the 1996 IUCN Red List of Threatened Animals.
The assessment is based on past records of rapidly declining local populations of basking sharks as a result of short-term fisheries exploitation and very slow population recovery rates recorded (see fisheries accounts in the following pages). It also takes into account the likely potential for similar population declines to occur in the future from directed fisheries, driven at least in part by the demand for fins in international trade, and from continued global by-catch. Several authors describe fisheries for other sharks that have caused serious stock declines (e.g. Ripley 1946, Olsen 1954, Rae 1962, Holden 1968 and 1974, Casey et al 1978, Gauld 1989, Cailliet et al 1993). Compagno (1984) considers the basking shark "to be extremely vulnerable to overfishing, perhaps more so than most sharks ... ascribed to its slow growth rate, lengthy maturation time, long gestation period, probably low fecundity and probable small size of existing populations (belied by the immense size of individuals in their small schools)." The best estimates of age at maturity for basking sharks are 12-16 years for males, up to 20 years for females, with a litter size of six, and gestation period from 12 to 36 months. Longevity is likely to be 50 years. The interval between litters may be two to four years. (Pauly 1978 and in press, Compagno 1984, Fowler in press.) This is not excessive for such a large shark, considering the well-documented gestation periods of 18-24 months recorded for the much smaller spiny dogfish Squalus acanthias, collated by Camhi et al. 1998.
No firm estimates are available for the total global population or regional populations of this species. Owen (1984) suggested that numbers sighted during aerial surveys for cetaceans and turtles in the Northwest Atlantic, which covered about 10% of the shelf area and could only identify sharks swimming at depths of less than 3-4 m, might represent only 1/7th of the total population present. On this basis, he estimated that as many as 4-6,000 sharks might be present in the Gulf of Maine and off the New England coast (USA) during the summer months. He compared this with an estimated population of 2,000 sharks in the Monterey Bay area of the US west coast (Squire 1967). McNally (1976) reports that a fishery removed 12,360 basking sharks over a 29-year period from the west coast of Ireland, the majority during the 1950s. The Norwegian fleet took another 800 in the area from 1973-83, and presumably significant numbers before 1973, when records by ICES (International Council for the Exploration of the Sea) Fishing Area become available (Annex 2b). Recent sightings data (Berrow & Heardman 1994) suggest that this population has not recovered since the main Irish fishery closed in the 1970s, following many years of low catches.
As pointed out by Compagno (1984), it should be noted that basking shark populations are probably very small compared with most other sharks. Most recorded fisheries have taken only hundreds or about one thousand individuals annually for a few years before collapsing. The maximum annual recorded catch throughout the northeast Atlantic only occasionally exceeded 3,000 individuals, at the peak of the Norwegian fishery, when more than 30 Norwegian vessels participated for the whole or part of the season (ICES1995). Where observations of basking sharks have been recorded, the total annual number of records is usually in the tens, hundreds, or at most low thousands, including repeat sightings. The Marine Conservation Society obtained 2,610 records with information on 9,064 sharks (doubtless including many repeat sightings) from UK waters from 1986 to 1988. The total number removed from the whole of the Northeast Atlantic during the past 50 years is probably between 80,000 and 100,000 animals (Annex 2a).
2.4 Population trends
A few well documented declines in catches by directed fisheries for the basking shark suggest that stock reductions of at least 50% to over 80% have occurred in some areas over a very short period (usually ten years or less, Fowler in press; Annex 1). These declines have resulted in long-term (lasting several decades) reductions in local populations, with apparently little or no migration into the area from other sources. Examples from Ireland, Japan and British Columbia are given below. However, most other fisheries described in literature (also summarised below) lack accurate recorded data on landings, market conditions and catch per unit effort. It is therefore not always possible to determine whether a short-term fishery ends for market reasons, or because the local population has declined to a point where difficulty in finding the target animals damages the viability of the fishery. Calculations of natural and fisheries mortality derived from north-west European landings (see following paragraph), however, strongly suggest this species is unable to withstand targeted exploitation for long, and confirm that stock depletion is likely to be a major factor affecting fisheries yields.
Pauly (1978 and in press) re-analysed previously published length-frequency data for north-west European basking sharks, mainly obtained from juvenile strandings and adults taken by a Scottish fishery. He modelled growth using the von Bertalanffy growth formula, and estimated total mortality (Z) as 0.33/yr for juveniles (considered too high to represent natural mortality) and 0.16/yr for adults. Adult natural mortality (M) calculated from Pauly (1980) produced an estimate of M = 0.068/yr for adults. Fishing mortality (F) was considered to be 0.094/year in adults, with the ratio of F/Z = 0.6. Pauly (in press) states that this is 'an exploitation rate that no fish - especially not a long-lived, low-fecundity fish such as the basking shark - can withstand for long (Beddington and Cooke 1983)'.
An additional explanation for the rapid collapse of localised fisheries for a widely distributed and apparently seasonally migratory species, is that basking sharks are site-faithful and tend to return to the same coastal summer 'basking' and feeding locations. Despite their wide-ranging nature, they are effectively part of local stocks that are particularly vulnerable to depletion by fisheries activity (Fowler 1996 and in press). Individuals of several other species of large migratory sharks have been found to return seasonally to the same general location to feed, mate, or give birth. Walker (1996) describes examples of localised stock depletion in wide-ranging shark populations. Hueter (1998) suggests that this pattern of 'philopatry' may occur in many species of shark and lead to localised stock depletion. In effect, there are likely to be sub-populations of basking sharks present in many (if not all) coastal areas, but the degree of exchange between these is unknown. Watterson (in lit.) has seen over 35 individuals returning to the Isle of Man (a UK Crown Dependency), some over a four or five year period. Individual sharks have been recorded as remaining in the area for up to 27 days. One South African basking shark has been re-sighted off Robben Island, Cape Town, on more than one occasion (Compagno, pers. comm.). Sharks marked in the Isle of Man have, however, also been re-sighted in other locations; one each on the west coast of Scotland, southern England, and south-west Ireland, possibly during other stages of their seasonal migrations (Watterson pers. comm.).
There is only very limited information available on wider population trends; data indicating changes in catch per unit effort or annual variation in numbers of sightings are only obtainable on a local, or at most regional, scale. Standardised sightings per hour data from the Isle of Man, where the species has been protected since 1990, suggest a decline in shark numbers from the end of the 1980s, with particularly poor sightings in the mid 1990s (Table 1 and Figure 1). Sightings data corrected for effort from a coastal cetacean-watching site in Cornwall for the period 1995-1998 show no significant trend (Speedie in lit.). Other sightings schemes (Scottish Wildlife Trust and Marine Conservation Society) do not correlate sightings with observation effort and so do not enable trends to be assessed reliably. MCS data (Table 2 and Figure 1) still appear to show a decline in reported sightings between the two periods when the public sightings scheme was actively promoted in 1988-91 and 1995-96.
Table 1. Number of basking sharks sighted per hour effort around the Isle of Man (Watterson in lit.)
Table 2. Sightings reported to the Marine Conservation Society, 1986 to 1998.
No of reports
No. of sharks
(* years during which the sightings scheme was promoted.)
Some evidence exists for unpredictable cycles in the numbers of basking sharks entering coastal waters. Certain years (including 1998) have seen very large influxes of sharks to some UK areas, while in others the numbers recorded are low (Kunzlik 1988, Speedie 1998, Fairfax 1998). Landings throughout the Northeast Atlantic have also fluctuated strongly. This annual variation in sightings and catch records may, however, be strongly influenced by weather conditions, since basking sharks are generally most commonly sighted on the surface in calm conditions, when they are also most vulnerable to surface harpoon fisheries. Water temperature may also have a significant effect on numbers seen; unusually warm or cold years may result in fewer sightings, possibly a reflection of food availability or distribution through the water column. Finally, basking shark sightings are often associated with the presence of coastal or oceanic fronts, where zooplankton may congregate. Such fronts may be more persistent and sharks more abundant in years when weather conditions are particularly favourable or if incursions of oceanic water into coastal areas occur. The latter may take place as part of a long-term cycle (e.g. the Russell cycle in the English Channel, Russell 1936, Southward 1980), but shorter cycles of six and three to four years are also reported by Robinson and Hunt (1986). In these circumstances migrating sharks may spend longer feeding on high densities of plankton and delay their onward migration to other preferred summer locations.
Some of the fluctuations in north-east Atlantic catches (Figure 4 and Annex 2) may be the result of cyclical fluctuations in zooplankton abundance linked to broad-scale oceanic changes controlled by factors such as summer stratification, the North Atlantic Oscillation or climate (Reid & Planque, in press). Associated changing patterns of basking shark activity may make populations more, or less, vulnerable to fisheries in some years than in others An alternative explanation may be that the wide-ranging Norwegian fleet identified and fished out several local stocks sequentially, resulting in a series of peaks and troughs as each stock was targeted. Neither hypothesis can be tested due to the absence of location data for the majority of catches. The life history of the basking shark, with late maturity and low birth rate probably means, however, that any short-term fluctuations in sightings or catches are not reflections of natural fluctuations in total abundance, but of variations in distribution and / or vulnerability to surface harpoon fisheries.
The collapse of two historical fisheries off the Irish coast are well documented: the 18th to 19th Century Sunfish Bank fishery, and the mid-20th Century Achill Island fishery (McNally 1976, Parker & Stott 1965).
The Sunfish Bank is located 30-40 km off the coast of Galway and Mayo, parallel to the coast between Slyne Head and Erris Head (including Achill Island) and not far from the edge of the Continental shelf. McNally notes that it was described in 1836 as being 'remarkable for the break of tide on it, with ebb and flood' (the conditions within which large aggregations of basking sharks are frequently reported elsewhere today). The Sunfish Bank and Achill Island were two of the main areas where large numbers of basking sharks were taken by small boats and relatively primitive equipment at the end of the 18th and first quarter of the 19th Century. Records from this period suggest that this fishery was active for several decades, between 1770 and 1830. The season only lasted for a few weeks in April and May, but at least 1,000 fish (probably more) seem likely to have been taken each year at the height of the fishery. In the early 1830s, sharks became very scarce. Despite continued high prices for 'sunfish' (basking shark) oil, the fishery collapsed in the second half of the 19th Century. A few years' shortage of sharks may be due to adverse weather conditions, but this lack of sharks lasted for several decades. There is no evidence that the collapse of the fishery was due to market factors. The decline in the fishery started 20 years before paraffin became widely available, shark oil was still more valuable in Ireland than paraffin in 1855, and profits to be made from basking shark catches were recorded as being extremely high in 1875, to the extent that 'lives were risked to secure a fish' (McNally 1976).
Basking sharks were next recorded in abundance around Achill Island in 1941 (McNally 1976), although numbers had presumably been increasing for some time. This was some 50 years after the previous fishery in the area had ceased, and more than 100 years since large numbers of shark had been taken off this coast A new fishery based on entangling sharks in nets in Keem Bay on the Island started in 1947. Between 1,000 and 1,800 sharks were taken each year from 1951 to 1955 (an average of 1,475/year), but a significant decline in catch records occurred from 1956 onwards. Average annual catches were 489 in 1956-1960, 107 in 1961-65, and then about 50-60 per annum for the remaining years of the fishery (Figure 2).
There is no evidence that this steady decline in catches was the result of a significant decline in fishing effort, which is considered to have been fairly constant at this shore-based fishing station. It is more likely to reflect the falling numbers of sharks entering Keem Bay, as a result of a steeply declining regional shark population. Fishing effort actually increased in the early 1970s as a result of increasing oil prices and re-investment, and catches rose elsewhere (see below). Harpoon guns were installed on three Achill Island boats in 1973, enabling the fishermen to move out of the Bay to the coast of Galway. Regardless, the fishery was unable to increase landings and closed in 1975 (Kunzlik 1988). A total of 12,360 fish had been taken in 29 years at this one site, with 10,676 of these caught from 1949 to 1958 (see Figure 2 and Annexes).
Another Irish basking shark fishery started in county Waterford (southeast Ireland) in 1974, taking an estimated 180 sharks that year and 350 in 1975 (McNally 1976), and confirming the value of basking shark products at this time.
The collapse of the Achill Island fishery was likely accelerated by the activity of Norwegian basking shark fishermen in west Irish waters, including the Sunfish Bank and other areas offshore from Achill Island (S. Myklevoll pers. comm., quoted in Kunzlik 1988). The numbers of sharks taken by this fleet in Irish or any other EC waters were not reported before 1973, so the proportion of earlier Norwegian catches taken in Irish waters is unknown. ICES Fishing Area landings records from 1973 indicate that a few hundred sharks were taken off the west coast of Ireland by the Norwegian fleet in 1973-74 (Area VIb-c), but Norwegian catchers were active off west Scotland in 1975 (Figure 3 and Annex 2b). However, total Norwegian landings for the whole northeast Atlantic (including Norwegian and Scottish coastal waters) were still relatively low during the initial period of decline at Achill Island (Figure 4). It seems likely that, as in later years, the majority of their catches were being taken off the Norwegian coast at this time.
Fowler (1996 and in press) suggests that the percentage decline in the regional population of basking sharks which occurred off the west coast of Ireland during these fisheries, as indicated by the steep and long-lasting decline in catches, was certainly greater than 50%. Indeed, considering Irish landings alone, the most recent Achill Island fishery appears to have caused a local population decline of over 80% in less than ten years. Average catches during the final 15 years of the fishery were less than 10% of the yields in the early 1950s. When the Norwegian catches from this area of the Irish coast are taken into consideration (so far as is possible in view of the lack of catch data by ICES Area for the 1950s and 1960s), then the regional population decline may have been even greater.
Despite incomplete data for Norwegian fleet catches in the area, the Achill Island catch data are considered to broadly reflect a general decline in the regional population of basking sharks on the west coast of Ireland as a result of this fishery. Evidence outlined above for localised stock depletion as a result of fisheries for other species of shark (Walker 1996) supports this theory. While such declines in landings may, in the short term, be due to weather conditions, Berrow & Heardman (1994) note that there were still very few observations by fishermen of basking sharks recorded along this whole west and north-west coast of Ireland in 1993, compared with other previously un-fished coastal areas. Another reason suggested for the decline in the Achill Island fishery is that there was a decline in zooplankton abundance over the same period, which may have affected the number of sharks available to harpoons at the surface (Anon., in press; Reid & Planque, in press). If so, this decline has lasted for forty years.
Fairfax (1998) summarises the limited information available on the earlier 18th and 19th century fisheries in Scotland. These appear, like the Irish fishery, to have ceased by the mid 1830s, with large numbers of sharks not being reported again until the 1930s. Fairfax (1998) and Kunzlik (1984) present data on landings from the 20th century Scottish basking shark fisheries, which concentrated on the Firth of Clyde and West coast (see Annex I). Several such fisheries started up in the 1940s, some targeted full time at the basking shark during the summer season, while others were more opportunistic. Regardless, all appear to have ceased after only a few years of good catches (Figure 4, Annex 2a). It is unclear whether this fishery was short-lived because of stock depletion (by the Scottish fishermen themselves, or Norwegian shark catchers operating close to the west coast of Scotland), or because of falling oil prices in the 1950s.
Oil prices rose again in the mid 1970s, Norwegian catchers took several hundred sharks in 1975, some Clyde basking shark by-catch was processed in the late 1970s, and a small target harpoon fishery started again in the Clyde in 1982. Initial yields from this fishery were good, but these were extremely short-lived and the fishery ceased at the end of 1994 after several poor years of catches (Fairfax 1998, Annex 2a).
Northeast Atlantic Norwegian fishery
A very wide-ranging Norwegian fleet, whose geographical and temporal distribution changes markedly from year to year (Stott 1982), has undertaken the major basking shark fishery in the Northeast Atlantic. Landings have been made from local fisheries from the Barents Sea to the Kattegat, across the North Sea to the south and west of Ireland, west coast of Scotland, Iceland and Faeroe (Pawson and Vince 1998), and have fluctuated widely (see Figures 3 and 4 and Annex 2).
Catches were at their highest (>1,000 and up to >4,000 in some years) between 1959 and 1980, when over 30 vessels were active for all or part of the season (ICES 1995, Figure 4). Shark oil prices were particularly high from the mid-1970s to the early 1980s, and fishing effort is therefore thought to have remained fairly constant over this period.
The subsequent decline in this fishery has been attributed (ICES 1995) to the ageing inshore whaling fleet that targeted basking sharks and a decline in value of basking shark liver oil in the late 1980s. (The latter was the result of the competition from the gulper shark Centrophorus granulosus and kitefin shark Dalatias licha fisheries.) This trend would, however, appear to have been offset by the greatly increased value of the fins in international trade in the 1990s. Regardless, at the present time only a few vessels now continue to fish for this species. A future increase in the activity of the Norwegian inshore whaling fleet may lead to increased opportunistic targeting of basking sharks.
Since the precise locations from which the Norwegian fleet fished for basking sharks are uncertain for the first 27 years of the fishery, it is difficult to detect and evaluate trends in catches, effort, and hence population. Figure 5 presents all landings data combined from the Northeast Atlantic since fisheries restarted in the 1940s, with running means added to smooth the fluctuations that may (as discussed above) be the result of climatic or oceanographic factors. This clearly shows a persistent decline in average landings from the early 1970s to the early 1990s. This period of decline includes a period of peak demand and high value for basking shark oil from the mid 1970s to mid 1980s, which encouraged the establishment of new fisheries in southern Ireland and the Firth of Clyde, Scotland. According to ICES (1995), the Norwegian fleet only declined significantly after 1980, and effort has largely been concentrated off the Norwegian coast since 1984.
Although no effort data are available, it may be concluded that the declining catches from 1970 to 1980 represent falling yields from declining stocks (possibly despite increased fishing effort), rather than declining fishing effort. This pattern of steeply declining catches is certainly a familiar pattern in other fisheries for large sharks, where much better records, including catch per unit effort data, are available.
Landings increased slightly in the early 1990s (Figures 4 and 5), when the fishery was being sustained by the high value of the fins (ICES 1995, quoting Dr S Myklevoll). The main market for Norwegian fins appears to be Japan, and exports to this market were also increasing steadily in the early 1990s (Directorate for Nature Management, 1995, quoted in Castro et al. in preparation). Norwegian catches have since declined to a new low, despite the continued high value of these products and demand in international markets.
Lien and Fawcett (1986) report on an incidental fishery for basking sharks by salmon and cod fishers in Newfoundland. Basking sharks have been incidentally entangled in set nets and occasionally sold for their liver oil for a long time in the area, but written records of these catches are scanty. An estimated 410 sharks were taken from 1980 to 1983 when a survey was carried out of collisions by cetaceans and basking sharks with fishing gear. Incidental shark catches increased in 1981 when a market developed for the fins and liver. When there is no market for the sharks' fins and livers, salmon fishermen generally remove their gear from the water to prevent damage when basking sharks are known to be in the area. If there is a market, the incidental catch becomes a target catch: fishing gear is left in the water and any fish caught is killed and landed, rather than released.
Basking sharks are common in the traditional knowledge of the Hesquiat and Ahousat people along the central west coast of Vancouver Island. In the 1940s, salmon fishermen complained about the problems with these fish being caught in their nets in Barkley Sound, Vancouver Island. The Department of Fisheries and Oceans therefore ran a shark eradication programme in the 1950s. A large blade was placed on the bow of Fisheries vessels and the sharks were rammed and killed. Information on the numbers of fish killed in this manner varies. Newspaper articles report a maximum of 31 being killed in one day and 50 in the first month of operation in 1956, and a total of 59 sharks killed in 1955 and 51-56 in 1956. Clemens and Wilby (1961) state that 'several hundred' were killed in Barkley Sound up to 1959. Presumably the programme ceased when numbers had been depleted to the extent where basking sharks were no longer posing a significant problem to the salmon fishermen. Darling and Keogh (1994) state 'Basking sharks are rarely sighted in Barkley Sound today, suggesting that the majority of the population in that area were killed.' It seems that a single vessel managed to deplete significantly the Barkley Sound stock of basking sharks over a period of just a few years. This occurred between 35 and 40 years ago, but the population has not recovered.
Basking sharks were only taken occasionally during the winter in Californian waters before a directed fishery commenced. Harpooning was initially only for sport, with carcasses incidentally being processed for oil and fish meal. However, the value of these products increased until the fishery became profitable and was operated from two centres: Monterey Bay and the San Luis Obispo Bay to Morro Bay area, 100 miles to the south. These two small areas are the two most important locations for winter concentrations of basking sharks along the central and northwestern southern Californian coast (Squire 1990). An average of 25 sharks per annum was landed during each season (September to May) from 1924 and 1938, with a maximum of about 100 in a single year. The fishery was inactive for several years, possibly due to wartime operations, then was revived in autumn 1946 to develop new uses for the valuable liver oil. It was also intended to process the carcasses for their very thick leather and for animal feed meal, and dry the fins for export to China. Three hundred basking sharks were taken in the first season, with 12 vessels operating in Monterey Bay and about six in the San Luis Obispo Bay area. Some vessels were directed to basking sharks on or near the surface by a spotter plane (Phillips 1947). This fishery continued until the early 1950s with about 200 sharks taken annually (Roedel and Ripley 1950). Squire (1967) reports that the fishery was suspended in California in 1950, because of the low prices paid for the oil and the low availability of basking sharks. Lea (pers. comm.) reports that basking shark sightings off central California over the past 20 years are not as numerous in the past. It has been suggested that the early 1940s and 1950s fisheries reduced the populations substantially, and that the species has never fully recovered. However, basking sharks are still taken incidentally in the area. Finned, but otherwise intact, carcasses have been reported washed up at intervals over the past few years (Sean van Sommeran pers. comm.).
The main targeted Japanese basking shark fishery used to take place off Nakiri, on the Shima Peninsula, Mie Prefecture. Basking shark hunting is recorded as a traditional activity here since the Edo era (1772). However, basking sharks were also taken as by-catch in the 1960s in set nets in the Nakiri area and elsewhere (including Onahama on the Pacific coast of Middle Japan, and near Tokyo). The fishing season was during the main basking shark migration through the area from March to May. Sharks were most abundant in March when the water temperature was about 14° C. About 65-70% of all sharks caught in the fishery was female, and males caught were found to be holding sperm in their claspers, indicating that mating activity was likely underway during this part of the year.
The basking shark fishery became more intensive in 1967 when oil prices rose, and Nakiri fishermen began harpooning larger numbers of sharks. The fishery used vessels of under 3 tons with a crew of two (one harpooner and one skipper). The fishing boats usually worked in pairs, one acting as the catcher and the other towing the sharks. The main use for the sharks during this period was the valuable squalene-rich liver oils. Shark fin was also important and considered a middle ranked shark fin in Taiwan. Shark meat was sold for human consumption, or processed into fishmeal for animal feed.
During the 12-year period from 1967 to 1978, more than 1,200 individual basking sharks were harpooned (an average of about 100 per year). During the last few years of the fishery, from 1975 to 1978, catches gradually decreased, from about 150 sharks in 1975, to about 20 in 1976, nine in 1977, and six in 1978. The fishery ceased completely in the early 1980s as a result of falling oil prices and the declining numbers of sharks sighted. In the 1990s, only 0-2 basking sharks have been sighted each year off Nakiri during the migration season. This compares with a peak year in 1972, when more than 60 basking sharks were processed for sale in Nakiri market. (This information was compiled from Yano 1976 and 1979, and Uchida 1995.)
Parry-Jones (1996a in Phipps 1996) reports that basking sharks used to be landed by a harpoon fishery in Fujian Province and Guangxi Zhuang Autonomous Region up to the 1970s. The species was commonly caught in the 1960s, but is seldom landed now. The report concludes that catches and landings of this species had decreased over the last 40 years, and recommended prohibition of catches of this species (and whale sharks Rhincodon typus) in near-shore waters as a precautionary measure until their status is ascertained.
2.5 Geographic trends
The species is widely distributed in temperate waters, but large numbers tend to be concentrated in only a few favoured coastal areas where feeding and possibly breeding activity takes place at or near the surface. As noted above, basking sharks are most vulnerable to target fisheries where they occur in such surface aggregations, and greatly reduced population numbers have persisted for decades in formerly favoured locales that were fished heavily. In addition, cyclical variations in patterns of sightings or catches of this species have been reported. For example, the Norwegian fishery demonstrated widely fluctuating landings during its peak 20 years of operation, and short term variations in local abundance of basking sharks sighted are also recorded from time to time (Kunzlik 1988, Speedie 1998). These may be linked to alterations in oceanic currents, water temperature and zooplankton aggregations. Long and short-term cycles in plankton abundance have been reported in the Northeast Atlantic and North Sea, with different patterns of abundance being recorded in different areas (Reid et al. 1998 a and b). For example, the abundance of Calanus finmarchius, a significant component of zooplankton, has declined in the north-east Atlantic, in some areas by as much as 50% since 1970 (UK BAP in press). This may also have some influence on basking shark distribution and abundance or availability to the fishing fleet.
2.6 Role of the species in its ecosystem
The role of the basking shark in its ecosystem is unknown, but as a large (up to 10m long) plankton feeder this will presumably be similar to that of the smaller baleen whales.
The main threat to basking shark populations is from fishing operations - both targeted on basking sharks and incidental or by-catch in other fisheries. However, because these fish congregate in bays and shallow water, they are also at risk from collisions with vessels and may be harassed by shark watchers. Collisions appear to be a fairly frequent occurrence - large areas of scarring are often observed on the head and dorsal surfaces.
Targeted basking shark fisheries use nets to deliberately entangle the fish or harpoon guns to take basking sharks swimming or feeding on the surface. Targeted fisheries have been recorded from Norway, Ireland, Scotland, Iceland, California, China, Japan, Peru, Ecuador (Compagno 1984) and Northern Spain (Evaristo Alfaya pers. comm.). Some of these are described in detail above. The main product of these fisheries has traditionally been the liver oil, although the meat, skin and cartilage are also used, and fins are now a very important product of modern fisheries because of their high value in international trade.
Incidental fisheries take is mainly recorded in set nets and trawls, and is most common in coastal waters. It naturally occurs over a much larger area than targeted fisheries. There is evidence from Newfoundland (Lien and Fawcett 1986) that some incidental fisheries may become targeted fisheries as markets for the products develop. There are reports of finned basking sharks being washed up dead in areas where no directed fisheries are known to exist (e.g. Monterey Bay, van Sommeran pers. comm.). Berrow (1994) extrapolated from very limited observer data to suggest that 77-120 sharks may be taken annually in the bottom set gill net fishery in the Celtic Sea (south of Ireland), though the reliability of this estimate has been questioned (P. Kunzlik in litt.). Berrow and Heardman (1994) received 28 records from fishermen of sharks entangled in fishing gear (mostly surface gill-nets) around the Irish coast during 1993, representing nearly 20% of all records of the species that year. At least 22% of basking shark by-catch in fishing nets died. By-catch in Isle of Man herring fishery has amounted to 10-15 sharks annually, and a further by-catch source here is entanglement in pot fishermens' ropes, amounting to some 4-5 fish annually (Watterson in litt.). Lien and Fawcett (1986) record that at least 410 basking sharks were caught between 1980 and 1983 in salmon gill nets and cod-traps in the coastal waters of Newfoundland. Some basking sharks were also taken in deepwater trawls nearby during the winter months. Fairfax (1998) also reports that basking sharks are sometimes brought up from deep water trawls near the Scottish coast during winter - either in a torpid or lively state. In contrast to these relatively large coastal by-catches, extrapolation of observer data from oceanic gill net fleets suggests that only about 50 basking sharks were among the several million sharks taken annually offshore in the Pacific Ocean (Bonfil 1994).
Basking sharks caught incidentally during fishing operations for other species are sufficiently resilient to be released, apparently unharmed in many cases, possibly even after up to three hours on the deck of a fishing boat (Lien pers. comm. and Watterson in lit.). The survival of sharks returned in this way is not monitored. However, the high value of their fins (and to a lesser extent liver oil, flesh and cartilage), is a strong incentive for fishermen to kill and utilise rather than release this species.
3. Utilisation and trade
The basking shark reaches weights of up to seven metric tonnes (it is the second largest fish in the world, after the whale shark Rhincodon typus). The main parts utilised are the liver, which comprises about 17-25% of the body weight and yields 60-75% oil (Phillips 1947, McNally 1976), meat and fins. The cartilage and skin are of secondary importance. The main traditional product of the basking shark fishery was the liver oil. Its use for lighting and other purposes is documented since at least the 17th Century in the UK and presumably took place much earlier here and in other regions. The meat has also been utilised, either fresh or dried, for food or fishmeal, since early fisheries. It was the secondary product of most traditional fisheries, after oil, but is still valuable in some areas. Fins are recorded as a by-product of the Monterey fishery in the 1940s, and were an important product of the Irish fishery by 1960. The increased value of fins during the past decade means that they are now probably the major incentive for continued directed basking shark fisheries in some regions. The cartilage has been used to produce fishmeal, and more recently for medical research and the manufacture of cartilage capsules for the health market. The thick skin can yield high quality leather.
The lack of detailed fisheries landings records and trade data at species level, and for specific shark products, presents a major obstacle to determining precisely which products and what quantity are utilised nationally by fishing nations, and which enter international trade (Rose 1996). However, some information can be obtained from literature, personal communications and TRAFFIC reports on the International Shark Trade. Even where basking shark products are eventually utilised in their country of origin, this may often follow initial export in 'raw form' for processing and re-import as a marketable product.
3.1 National utilisation
The livers were, until recently, the main product of basking shark fisheries, originally mainly to supply domestic markets. Indeed, some fisheries formerly removed the livers from the fish at sea and discarded the remainder of the fish. A large shark can provide about 0.7 t (metric tonnes) of oil, but the average is considered to be about 0.4 to 0.5 t per fish. This oil has a very high squalene content (up to 55%, Buranudeen & Richards-Rajadurai 1986), characteristic of deep water sharks, and is therefore primarily of industrial rather than medicinal value. (Liver oil high in vitamin A and D is characteristic of shallow water sharks; the vitamin A content of basking sharks is highest in autumn after a period spent on the surface.) Traditional basking shark fisheries supplied oil for lighting, but it is now used for certain manufacturing processes and for lubrication of machinery. The large amount of oil derived from a single shark has made these fisheries viable in the past, but the liver oil market is presently suffering from competition from the gulper shark Centrophorus granulosus and kitefin shark Dalatias licha fisheries (ICES1995). T he oil is used in Norway for the extraction of squalene and supplies the cosmetic and health supplement markets (Fleming and Papageorgiou 1996). As a result of falling oil prices in recent years (see 3.2), the Scottish fishery was discarding the livers at sea, but landing the flesh and fins. It is uncertain how much of the liver oil landed in most countries is utilised nationally today, but all or most oil landed in the UK in recent years appears to have entered international trade, mainly through export to Norway.
The flesh of basking sharks, when not discarded at sea, has been used both to produce fish meal and, dried or fresh, for human consumption. McNally (1976) records that meat was sold at £2.50 to £3 per ton (£2.54-3.05 per metric tonne) in the early 1960s, which made processing uneconomic. Basking shark flesh was sold in Billingsgate market in the 1970s, and in fish and chip shops in Scotland in the 1980s and early 1990s. Prices for the meat were £0.30 to £0.80/kg in the early 1990s (Fleming and Papageorgiou 1996). Chen et al. (1996 in Phipps 1996) give a landing value at fishery markets for whole basking sharks in Taiwan as US$1.10/kg.
Fins landed in Europe and other fishing nations outside southeast Asia are mainly thought to be directed into the international trade, and are not utilised nationally to any significant extent. Fins landed in China and Japan may be used by domestic markets, or exported for processing. Basking shark fins may be re-imported to any country in processed form, but if no longer whole are unlikely to be recognisable as this species.
Basking shark cartilage is probably only used domestically in small quantities, and may be exported in 'raw' form before being re-imported as a processed product for use in its country of origin. The large size of the basking shark will likely make the processing of its cartilage more cost effective than cartilage of smaller sharks, increasing the demand for this species.
No information was obtained on present national utilisation of basking shark skin for leather manufacture.
3.2 Legal international trade
Four basking shark products are known to enter the international trade in significant (albeit largely unrecorded) quantities; liver oil, fins, cartilage and meat. However, no customs data are available on quantities of shark fin, cartilage or oil imports and exports by individual species, and most countries which keep any records of trade in sharks separately from other fish, combine all shark products into a single category. It is therefore impossible to determine precisely the volume of basking shark products which enter international trade or from which populations these products originate. The following information was obtained from literature and TRAFFIC surveys.
The value of the oil has declined in recent decades. McNally (1976) records liver oil prices in Ireland as follows: £140/ton in 1947, £90-110 in 1948, £70 in 1949 and up to £500 per ton (£508/metric tonne) in 1974 (due to the high cost of oil imports from the major oil producing countries at this time). Fleming and Papageorgiou (1996) give values of £600/t for liver oil landed in Scotland in the early 1980s, but this had fallen to £230/t in the late 1980s. Fairfax (1998) reports liver prices of £250/t (US$375/t) in the early 1990s, and notes that the liver was no longer landed in the last years of the recent Firth of Clyde fishery in Scotland because the high costs of exporting oil to Norway made exports uneconomic. The Norwegian fishery is reportedly still landing basking shark oil and has been importing large quantities of shark oil (from various species) over the past decade. However, their domestic fishery is apparently now only economic because of the high value of the fins (ICES 1995 quoting Myklevoll). Basking sharks caught incidentally by New Zealand fisheries are processed for their oil and fins, which are thought mainly to be exported. Where data are available for shark oil exports and imports, these do not differentiate between species of origin. Shark oil records may therefore represent products from basking shark, gulper shark, spiny dogfish, kitefin shark and other fisheries.
Norway is the only country that reports information to Food & Agriculture Organisation (FAO) on the shark oil trade. Norwegian imports have greatly exceeded exports in the period 1988 to 1994, but it is not clear whether processed and subsequently re-exported shark oil products will also appear in the Norwegian export statistics, or whether only unprocessed shark oil is recorded. It is extremely difficult to trace exports, imports and re-exports of processed liver oil capsules and other oil products.
The fins have a very high value in oriental markets. McNally (1976) notes that sales of fins had provided the Achill Island fishery with "a secondary, if relatively small source of income since 1960", when they were exported to Spain from Ireland. By 1970 fins were being exported directly to Hong Kong. Prices paid to fishermen for fins were £3,000/t in the 1970s, but had climbed to £20,000 (US$30,000)/t by 1994 (Fairfax 1998). (These prices are not corrected for the rising price index over this 20 year period, but the nearly 700% rise is significant, with much of this increase occurring in the late 1980s to early 1990s.) Fleming and Papageorgiou (1996) record that fins were exported from Scotland to Norway for US$6/kg (£4/kg) in 1983. Prices then rose, with a particularly rapid increase in the early 1990s, and fins for export were US$26.25/kg (£17.50/kg) in 1994, an increase of over 300% in nine years. Fairfax (1998) reports that the largest quantity of fins yielded by a single shark (a large female) in the recent Firth of Clyde fishery was 92 kg. The fins from a single fish will therefore be worth well over US $1,500 (£1,000), and up to US$2,400 (£1,600) to the fisherman. This high value is the main economic factor now sustaining the Norwegian basking shark fishery (Dr S Myklevoll, in ICES 1995). Norwegian fin exports to Japan have been steadily increasing: 0.096 t of fins were exported in 1992, 7.218 t in 1993, and 26.859 t in 1994 (from letter of Directorate for Nature Management, 21 September 1995, quoted in Castro et al. in preparation).
Prices for fins dried for processing are, of course, much higher. A Norwegian fin processor reported that the April 1996 price for dried basking shark fins was about US$130/kg (£90/kg) (Fleming and Papageorgiou 1996). Some fins might be used nationally by oriental restaurants in the countries of origin, but it is thought that virtually all fins taken from basking sharks in European waters and other areas outside Southeast Asia are likely to enter the international trade; some may later be re-imported in processed form. Lum (1996) reports that basking shark fins imported from Norway are the most expensive available in Singapore, at Sg.$400 (£200 or >US$300) per kilogram (dried), or Sg.$88 (£44) per bowl in restaurants.
Parry-Jones (1996b in Phipps 1996) quotes retail prices supplied by an experienced Hong Kong trader of US$25/kg, US$256/kg and US$330/kg respectively for frozen, dried and processed sets of basking shark fins (a fin set usually comprises two pectoral, dorsal and lower caudal fins). Another trader quoted a price of US$846/kg for a single fin weighing 7.3 kg (US$6,176 for the whole fin), presumed to be from either a basking shark or whale shark. In June 1998, a single 1 m high shark fin, considered likely to be from a basking shark, was on sale in a restaurant just outside Chengdu, Sichuan, China, for 80,000 yuan (slightly less than US$10,000) (Antony Whitten, pers. comm.).
It is impossible to determine the volume of cartilage entering international trade. However, Fleming and Papageorgiou (1996) report that cartilage capsules manufactured and on sale in pharmacies, homeopathic shops and health practitioners in Belgium are labelled as 'ex Ceatarinus maximus pulvis'. If this labelling is accurate, then the cartilage will certainly have been imported to Belgium; there is no basking shark population in the southern North Sea. This product is also exported from Belgium to France, Portugal, Germany and Switzerland.
Fleming and Papageorgiou (1996) report that the market for basking shark meat exports from Norway to Eastern Europe is increasing; at a 1996 value of about US$1/kg.
3.3 Illegal trade
All known international trade in basking shark products is legal. Illegal trade will only be taking place if products are derived from areas where the species is protected and where it has been taken illegally (e.g. those areas described in section 4.1); there is no evidence of this, but detailed trade records for this species are not kept.
3.4 Actual or potential trade impacts
The high value of basking shark fins in international trade is reportedly the reason why the Norwegian fishery for this species is still viable, now that liver oil prices have fallen (ICES1995). There is not thought to be any significant domestic market in Norway or other European countries for unprocessed basking shark fin, so it is concluded that the international trade in this product is the main impetus for this targeted fishery.
The value of international trade is also likely having a significant impact on mortality from incidental fisheries. As reported by Lien and Fawcett (1986), the presence of a market for basking shark products, including fins for international trade, encourages Newfoundland cod and salmon fishermen to continue to leave their nets in the water when basking sharks are present, risking collision, entanglement and damage to fishing gear. This is because the value of the shark products exceeds the cost of the damage they cause to nets. In the absence of a market for basking shark products, nets will be removed from the water when these fish are known to be in the area. In effect, the international market for basking shark products has turned an incidental fishery into a targeted fishery. The high value of international trade in basking shark fins also encourages the finning of basking sharks caught incidentally in other fisheries, which might otherwise often be released alive.
3.5 Captive breeding for commercial purposes
4. Conservation and Management
4.1 Legal status
The basking shark is fully protected from intentional capture or disturbance in British waters (to 12 miles offshore) under a 1998 listing on the Wildlife and Countryside Act (1981), Schedule 5.
Isle of Man
The basking shark is protected within a radius of twelve miles around the Isle of Man (a UK Crown dependency). Despite protection here since 1990, numbers of basking sharks recorded around the Island in recent years have been falling (see Table 1 and Figure 1 in section 2.4).
Guernsey, Channel Islands
The basking shark is strictly protected under fisheries legislation around Guernsey (a UK Crown dependency).
Florida state waters, USA
The basking shark, which is on the southern edge of its range in Florida, is fully protected in State waters (out to the three mile limit on the east coast, and nine miles on the Gulf coast).
Atlantic and Gulf federal waters (3-200 miles), USA
The basking shark is strictly protected under the US Fishery Management Plan. Directed commercial fishing and landing or sale (either by commercial or recreational fishermen) of the species is prohibited. This prohibition recognises the biological vulnerability (limited reproductive potential and slow surface movements) of the species and was enacted in order to prevent targeted fisheries from developing.
The basking shark is one of several fish species (including some teleosts) which have received partial protection through fisheries legislation (the Fisheries Act 1983). Commercial target fishing for the species has been banned since 1991, although they are allowed to be taken as by-catch. The liver and fins are landed in this way, and the fins almost certainly all exported. Two main concerns led to this ban on target fishing basking sharks in NZ: their vulnerability (presumed low reproductive rate, growth rate and population size); and secondly the introduction of a Quota Management System (QMS) in 1986. The QMS restricted fishing on main commercial species and reduced some catches substantially. As a result fishermen showed a lot of interest and innovation in looking for and catching non-quota species. The Ministry of Agriculture and Fisheries placed a prohibition on targeting species that were considered unlikely to support significant fisheries in order to prevent a surge in effort away from the quota species on to species for which there were no (or few) output and input controls, and no information on sustainable yields. (Malcolm Francis, pers. comm.)
The Barcelona Convention for the Protection of the Mediterranean Sea (1976) Protocol Concerning Specially Protected Areas and Biological Diversity in the Mediterranean was signed in Barcelona on 10 June 1995. The basking shark Cetorhinus maximus is listed on Annex II to the Protocol 'Endangered or Threatened Species' and will therefore receive full protection in the Mediterranean once the Convention is ratified and appropriate legislation in place. (Species receiving a lesser degree of protection are listed under Annex III: 'Species whose Exploitation is Regulated'.)
The basking shark (Mediterranean population only) was also added to Appendix II (strictly protected species) of the Bern Convention on Conservation of European Wildlife and Natural Habitats in December 1997. This listing has an EU Reservation, pending progress on the management of other protected species already listed on European legislation.
4.2 Species management
4.2.1 Population monitoring
Very little monitoring of this species takes place, and none provides sufficiently good information to enable population trends to be determined with any reliability. Catches of basking sharks are recorded by some fisheries departments, including Norway, New Zealand (incidental catches) and, formerly, Scotland. However, most (if not all) other countries reporting on their elasmobranch landings do not differentiate between species of shark (only providing figures for total tonnage landed); weights of products rather than numbers of fish are reported; and little or no effort data are available. Even where catches are reported accurately, there are no catch per unit effort data available to enable fisheries yields to be extrapolated to provide overall population trends.
Three public sightings recording schemes for the species are presently underway in the UK. A national project run by the UK Marine Conservation Society has been collecting records since 1986 and includes a few records from Ireland. A regional project in south-west England and adjacent areas (Seaquest) also contributes to the Marine Conservation Society's database. The Isle of Man basking shark project includes both an effort sightings scheme and a public sightings programme. The last of these also receives records from adjacent areas in England and Scotland (Watterson in lit.). Berrow & Heardman (1994) reported on a shorter-term project recording fishermen's sightings around the Irish coast.
All sightings are heavily dependent on weather conditions and observer effort. Variation between years in numbers recorded cannot, therefore, reliably be attributed to changes in population size, and sharks a short distance below the surface will usually not be recorded. As noted in Table 1, section 2.4, effort sightings data from the Isle of Man have shown a steady decline in shark numbers since the late 1980s. The same trend is apparent in the data from the UK Marine Conservation Society public sightings recording programme for the whole of the UK (Figure 1).
Some useful data may be available from aerial surveys for cetaceans and turtles, as demonstrated by Owen (1984), but basking sharks have not been a sufficiently high priority for inclusion in such sightings programmes.
There is a need to obtain much more reliable population and distribution data for the species, including information on directed and incidental fisheries landings, population dynamics, reproductive biology, and migrations between wintering and summering grounds and pupping areas. The draft UK Biodiversity Action Plan (Anon., in press) for the basking shark proposes to address some of these points.
4.2.2 Habitat conservation
4.2.3 Management measures
The only known fisheries management for this species followed the establishment of 200 miles fishery limits around European Community countries (including the UK and Ireland) in the 1970s. An annual quota for the Norwegian catch of the species in EC waters was first agreed in 1978, as part of a quota exchange for white fish in Norwegian waters. The basking shark quota stood at 800 tonnes liver weight in 1982 and has since steadily been reduced, to 400 mt liver weight (approximately 800-1000 fish) in 1985, then 200 mt, and has been 100 mt (or about 200-300 sharks per year at an average weight of 0.4-0.5 mt oil per shark) since 1994.
FAO International Plan of Action for the Conservation and Management of Sharks
Management and monitoring of the basking shark and other species of sharks will be required in future under the International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks), agreed at an FAO inter-governmental meeting in Rome, October 1998. This document was endorsed by consensus at the FAO Committee on Fisheries meeting in February 1999, and will be submitted for adoption by the FAO Conference in November 1999. The objective of this FAO IPOA is to ensure the conservation and management of sharks and their long-term sustainable use. It notes that the current state of knowledge of sharks and shark fisheries practices causes problems in the conservation and management of sharks due to the lack of available catch, effort, landings and trade data. Inter alia, the IPOA requires States that adopt the Plan (it is voluntary) to identify and pay special attention, in particular, to vulnerable or threatened species, and facilitate the identification and reporting of species-specific biological and trade data. CITES presently offers the only established, effective means of monitoring international trade data at species level.
4.3 Control measures
4.3.1 International trade
4.3.2 Domestic measures
5. Information on similar species
The basking shark is the only species of the family Cetorhinidae. It has a very distinctive appearance, and unlikely to be confused with any other species (except possibly for large specimens of the great white shark (Carcharodon carcharias) if it is not clearly seen in areas where their range overlaps - e.g. in southern Australia). The fins of the adults are extremely large and, for this reason alone, are very unlikely to be confused with those of any other species when detached from the body. The whale shark also has very large fins, but the skin of the whale shark (Rhincodon typus) is spotted and the fins are rounded at the tips, while the basking shark has pointed fin tips.
The order Lamniformes contains a total of 16 species in seven families, including the sand tiger sharks (Carcharias and Odontaspis spp.), thresher sharks (Alopias spp.) and mackerel sharks (Carcharodon carcharias, mako sharks Isurus spp., and Lamna spp.). The basking shark, whale shark and very rarely recorded deepwater megamouth shark (Megachasma pelagios) are the only known planktivorous sharks, but are not closely related.
6. Other comments
The addition of the basking shark to Appendix II of CITES is being proposed by the UK in order to ensure that future international trade and target and by-catch fisheries for basking shark are sustainable. The basking shark is now protected or partly protected within the territorial waters of the UK, USA, and New Zealand, and in Florida State waters. Legal protection is pending throughout the Mediterranean Sea and proposed in the territorial waters of other states. However, the species remains vulnerable to target fisheries once it moves out of these waters on migration. Unmanaged fisheries may, therefore, endanger the viability of legally protected populations of this vulnerable species. Available evidence already indicates that some basking shark populations are either very small, or showing a declining trend, or still at a low level following declines in previous decades. Recovery from depletion appears to be extremely slow and precautionary management is advisable for this species.
Basking shark products enter international trade and the fins are particularly valuable. Indeed, the high value of the fins in international trade is not only a major factor maintaining the viability of existing targeted fisheries, but also encourages incidental take in non-target fisheries which would otherwise remove fewer individuals from the population. No basking shark fisheries are managed, apart from a quota for the Norwegian fishery in European Union waters (which is not based on a stock assessment), and little or no fisheries or fisheries-independent research or monitoring is underway. This is despite the recognition by many countries that many fishermen are having to search for alternative quarry species as traditional fisheries decline, and that a valuable and vulnerable species like the basking shark is an easy potential target. Unfortunately, fisheries management plans are very slow to be introduced after a fishery has developed.
The recently agreed FAO International Plan of Action for the Conservation and Management of Sharks (IPOA-Sharks) acknowledges the increase in effort and catch of shark fisheries over the past few decades and that shark life histories make them vulnerable to over-fishing. Indeed, it recognises the need to pay special attention to vulnerable or threatened species, and to facilitate the identification and reporting of species-specific biological and trade data. However, the IPOA-Sharks is voluntary, and there is no mechanism, other than through a CITES listing, to enable the latter objective to be undertaken. A CITES Appendix II listing for the basking shark would enable Parties to fulfil part of the aims of the FAO IPOA-Sharks. I t would require exporting Parties to ensure that international trade (which drives many fisheries) was not detrimental to the survival of that species. It would encourage fisheries management and research to be introduced where it is presently lacking, to ensure sustainability of catches.
7. Additional Remarks
The vulnerability of the basking shark to directed fisheries as a result of its biology and ecology is already recognised by its 1996 IUCN Red List assessment of 'Vulnerable'. Additionally, several Parties to CITES have considered it necessary to introduce legislative measures to protect the species in their territorial waters. The following paragraphs assess the basking shark in terms of the CITES biological criteria.
7.1. Assessment of the basking shark under the CITES biological criteria
This proposal for the listing of the basking shark on Appendix II of CITES is based on the following assessment of the species' biological status, using CITES Appendix II listing Criterion Bi (see Box 1).
- The species has been subjected to unsustainable fisheries in several parts of the world, including the Northeast Atlantic, Northeast Pacific, and Northwest Pacific (see summary in Annex 1). All these fisheries appear to have exceeded sustainable levels and most caused population collapse in 10-20 years.
- At least some of the products of some of these fisheries have entered international trade.
- In recent years European basking shark fisheries have largely been supported economically by the high value of shark fin in international trade.
Criterion A is also met by this assessment, using Appendix I criteria C i & ii.
Box 1. CITES listing criteria
Article II Fundamental Principles
2. Appendix II shall include:
- all species which although not necessarily now threatened with extinction may become so unless trade in specimens of such species is subject to strict regulation in order to avoid utilization incompatible with their survival;
Criteria for the Inclusion of Species in Appendix II
A species should be included in Appendix II when either of the following criteria is met.
A. It is known, inferred or projected that unless trade in the species is subject to strict regulation, it will meet at least one of the criteria listed in Annex 1 in the near future.
B. It is known, inferred or projected that the harvesting of specimens from the wild for international trade has, or may have, a detrimental impact on the species by [either]:
- exceeding, over an extended period, the level that can be continued in perpetuity;
- [not relevant].
Biological Criteria for Appendix I
A species is considered to be threatened with extinction if it meets, or is likely to meet, [at least one of] the following criteria.
C. A decline in the number of individuals in the wild, which has been either:
i) observed as ongoing or as having occurred in the past (but with a potential to resume) ; or
ii) inferred or projected on the basis of any one of the following:
- levels or patterns of exploitation
- [others are not relevant].
A. When considering proposals to amend the appendices, the Parties shall, in the case of uncertainty, either as regards the status of a species or as regards the impact of trade on the conservation of a species, act in the best interest of the conservation of the species.
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Annex 1. Trends in fisheries yields or sightings for the basking shark.
Geographical area and description of records.
Average catches or sightings per year
Overall (decline) or increase in catches
Average (decline) or increase per decade
Achill Island, Ireland. A targeted coastal basking shark fishery
360/year in 1947-1950,
1,475/year in 1951-1955,
489/year in 1956-1960,
107/year in 1961-1965,
64/year in 1966-1970,
50/year in 1971-1975.
Rarely seen in 1990s
(>95% decline in 25 years)
1940s: increase as fishery develops
(1950s: 65% decline)
(1960s: 30% decline)
(1970s: 20% decline and closure)
West coast of Scotland
121/year throughout fishery.
142/year in 1946-1949,
100/year in 1950-1953.
(~30% in 7 years, but trend unclear)
(~30%, but trend unclear)
Firth of Clyde, Scotland
58.6/yr in first 5 years,
4.8/yr in last 5 years.
(>90% in 12 years)
837/year in 1946-1950
554/year in 1951-1955,
1,541/year in 1956-1960,
1,792/year in 1961-1965,
3,213/year in 1966-1970,
2,236/year in 1971-1975.
1,706/year in 1976-1980
797/year in 1981-1985
343/year in 1986-1990
403/year in 1991-1995
(87% decline from peak landings in late 1960s to levels in the early 1990s)
~200% increase, 1950s
~100% increase, 1960s
(1970s: 47% decrease)
(1980s: 80% decrease)
(1990s: 60% overall)
(all catches combined)
1,254/year in 1946-1950
2,094/year in 1951-1955,
2,030/year in 1956-1960,
1,899/year in 1961-1965,
3,277/year in 1966-1970,
2,385/year in 1971-1975.
1,706/year in 1976-1980
848/year in 1981-1985
355/year in 1986-1990
407/year in 1991-1995
(90% decline from the main period of peak landings in the late 1960s to landings in the late 1980s)
This followed 20 years of fluctuating but rising catches.
~40% increase, 1950s
~20% increase, 1960s
(1970s: 40% decrease)
(1980s: 65% decrease)
(1990s: 80% overall)
50-60/year killed in 1950s
<25/year sighted in 1990s
Data unclear, but a few years of catches resulted in an approximately 50% decline in sightings over 40 years.
300/yr in 1946
200/yr in late 1940s
Fishery closed, early 1950s
(30% decline in first few years, then fishery closed)
Data unclear, but a few years of high catches was followed by closure of the fishery.
127/yr average, 1967-1974
150 sharks in 1975
20 sharks in 1976
9 sharks in 1977
6 sharks in 1978
Fishery closed, early 1980s
0-2/year sighted in 1990s
(>95% decline in 10 years)
Data summarised for first eight years of the fishery, so early trends unclear, but the decline was rapid in the second half of the fishery and has persisted to the present.
No quantitative data. Reported to be common in the 1960s, occasionally caught in the 1970s, and rare in 1980s and 1990s.
(No quantitative data, but decline to very low levels reported.)
(No quantitative data, but significant decline indicated in the 1960s and 1970s.)
Isle of Man sightings
Table 1 presents steady decrease in sightings/effort.
(Average sightings declined by ~90%)
(Average sightings declined by ~90%)
Annex 2. North East Atlantic basking shark landings data.
2a. Targeted Northeast Atlantic basking shark landings (numbers of sharks caught), 1946-1996.
Other Irish catches
Annex 2b. Norwegian basking shark landings3, recorded by ICES Fishing Area from 1973.
Source: reports of the ICES Study Group on Elasmobranch Fishes.
3Numbers are derived by converting published landings (tonnes) to number of 5t fish. This may result in an under-estimate of the numbers of sharks taken by up to 30%.
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