© Chelsea Gray
SPECIES | Legal Status
Due to the extent of its range, basking sharks frequently move through jurisdiction of multiple nations and are thus subject to varied management efforts. The basking shark is currently not listed as a protected or restricted fish species under Irish National marine or conservation legislation. A Wildlife Trust - sponsored action plan has prompted a review of its status in the Northern Ireland Wildlife Order 1985. However, basking sharks are protected from capture and disturbance in British waters (up to 12 miles offshore) under the Wildlife and Countryside Act (1981). They are also protected within the territorial waters of the Isle of Man and Guernsey. More broadly, target fishing is prohibited in EU waters and Internationally by EU registered vessels (EC No41/2007 of the 21/12/2006 and equivalent Norwegian regulations). In the Mediterranean, this species is protected under the Bern Convention (with EU reservation) and Barcelona Convention (non-ratified). Directed fisheries are prohibited in New Zealand, but by-catch is landed. Similarly, throughout North American waters, target fishing for basking sharks is prohibited but by-catch is landed in the United States and Canada.
At a global scale, basking sharks are listed as vulnerable on the IUCN’s Red List in 2007 and endangered in the Northeast Atlantic and North Pacific. In 2002 the basking shark was successfully proposed as an addition to Appendix II of CITES by the UK and Australian governments. They are also covered under CMS Appendix I and II and Annex I of the United Nations Convention on the Law of the Sea (UNCLOS).
Though now protected internationally, basking sharks still face a variety of anthropogenic threats, including boat strikes, harassment by recreational boat users and habitat alteration due to the development of renewable energy infrastructure (Kelly et al., 2004). As filter-feeders, basking sharks are also vulnerable to the toxicological effects of microplastic consumption (Fossi et al., 2013). There also remains concern that the population has not recovered significantly from persistent fishing pressure in the twentieth century, although this remains difficult to resolve (Sims et al., 2005). Recent estimates suggest that the effective global population size of basking sharks is less than 10,000 individuals (Hoelzel et al., 2004). However, because most population censuses are based on a combination of genetic data and surface sightings, variation in movement and diving patterns likely affect this estimate. Any behavioral plasticity in both migration and hotspot use could also render current area-based protection measures (i.e. marine protected areas) less effective than previously considered (Doherty et al., 2017).
Sustainable mortality and by-catch rates have been calculated by Canadian researchers which show that the current by- catch in the Atlantic Canada region is above calculated sustainable mortality in the species. Consequently, the localised basking shark population is estimated to be on a negative trend (CSAS 2008). European and West African by catch reports also suggest that due to offshore target fishing (particularly by deep sea gillnets), total allowable catch (TAC) levels and by-catch are currently too high and under-regulated to enable sustainable shark populations in the eastern Atlantic (Berrow, 1994, Pauly, 2002, Lack & Sant, 2008, OCEANA, 2007).
ICUN guidelines therefore echo the advice of the International Council for the Exploration of the Sea (ICES) Working Group on Elasmobranch Fishes (WGEF) by suggesting that no target fishery of basking sharks should be permitted until a reliable estimate of a sustainable level of exploitation is first established.
RECENT ADVANCES IN
CONSERVATION AND RESEARCH
Up until the late 1990s and early 2000s, little research had been conducted on the basking shark, especially the population in the northeastern Atlantic. To date, only two pieces of scientific research have been published from Irish coastal waters, both of which were initiated by Dr S. Berrow in 1994. Between 2007 and 2008, however, a number of media articles were published to raise awareness of a tagging project conducted to determine the site fidelity of basking sharks in Irish coastal waters (Berrow, S.D., 2008, IWDG 2008, Derry Journal, 2008). It was during this time that the IBSP was founded, with the goal of establishing a persistent research and conservation effort in the country.
This effort mirrors a broader global trend. In recent years, a number of different research projects have been completed on the basking shark in neighbouring territorial waters. Among these are comprehensive ship- transect surveys of UK coastal waters, a number of geo-location satellite tagging projects, and the co-ordination of public sightings into a comprehensible database. Public awareness and education programmes have also been run in conjunction with these studies (Bloomfield & Solandt, 2006). In addition, numerous tagging and tracking projects have been initiated around the Gulf of Maine and up to Newfoundland by notable Canadian and U.S.A. based research institutes (CSAS, 2008). In the Pacific, the Canadian government also sponsored an aerial survey of its Pacific seaboard in 2008, with the intention of ascertaining a population estimate of basking sharks. However, no sharks were recorded (Dulvy et al, 2008).