FEATURE CREATURE
FEATURE CREATURE
BASKING SHARK (CETORHINUS MAXIMUS ) FEATURE IUCN RED LIST 2019 PHOTOGRAPHY SIMONE CAPRODOSSI
RED LIST CATEGORY & CRITERIA: ENDANGERED Scientific Name: Cetorhinus maximus Synonyms: Squalus maximus Gunnerus, 1765 Common Names: English: Basking Shark French: Pelerin Spanish; Castilian: Peregrino JUSTIFICATION The Basking Shark (Cetorhinus maximus) is a very large (to ~1,100 cm total length), highly migratory, filter-feeding shark distributed mainly in the Atlantic and Pacific Oceans in coastal and pelagic habitats from the surface to 1,264 m. It occurs near the surface in temperate waters and deeper, below the thermocline, in tropical waters. The species has low biological productivity with limited fecundity and late age-at-maturity. Although no longer targeted, it is still caught as bycatch in trawl, trammel nets, and set-net fisheries, and becomes entangled in pot lines. The large fins are extremely valuable in the fin trade. Across regions, there have been some severe historic decline, however there are indications of some stability and possible slow recovery since 18
DIVERS FOR THE ENVIRONMENT | JUNE 2020
cessation of target fishing and high levels of protection. The global population may now be beginning to stabilise, with signs of that from the Northeast Atlantic, although elsewhere there is little information upon which is assess stability. However, abundances are still estimated to be well below historic levels and there is ongoing demand for the highvalue fins, and a global population reduction of 50-79% is suspected over the past three generations (102 years).Therefore, the Basking Shark is assessed as Endangered. GEOGRAPHIC RANGE The Basking Shark occurs mainly in the Atlantic and Pacific Oceans; in the Indian Ocean, it is reported only from southern Australia, Indonesia, and South Africa (Ebert et al. 2013, Fahmi and White 2015). POPULATION There is no data on the absolute global population size, although it is likely to be greater than 20,000 individuals (and thus not approaching the thresholds for criterion C: small population size and decline). Genetic results indicate one global population (Noble
et al. 2006, Francis 2017). Basking Shark total abundances have been estimated for a number of regions: 4,200 and 632 (CI: 377-1,058) in the Bay of Fundy, Canada in 2007 and 2011, respectively (Campana et al. 2008, Westgate et al. 2014); 10,125 in Canadian Northwest Atlantic waters in 2007 (highly uncertain estimate) (Campana et al. 2008); 6,671-14,925 in New England shelf waters, United States in 1982 (Kenney et al. 1985); 985 on the west coast of Scotland in 2010 (95% CI: 495-1,683) (Gore et al. 2016); and, possibly 19,151 (+/10,629) for Scotland and Ireland combined (Gore et al. 2013). Landings and sightings data are available from the Northeast Atlantic (e.g. CITES 2002, Southall et al. 2005, Speedie et al. 2009, Witt et al. 2012, ICES 2018); landings data are available from Japanese waters (Yokawa 2017); and, sightings-per-unit-effort (SPUE) are available from New Zealand (Francis 2017, M. Francis unpubl. data). In the Northeast Atlantic, the landings of Basking Sharks declined dramatically during the period 1946-2017 (CITES 2002, ICES
