Pierce, S.J. and Norman, B. (2016) Rhincodon typus. The IUCN Red List of Threatened Species . e.T19488A2365291.
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The Whale Shark (Rhincodon typus), the world’s largest living fish, is a cosmopolitan tropical and warm temperate species. Genetic results indicate that two major subpopulations exist, in the Atlantic Ocean and Indo-Pacific, respectively.
Pronounced size- and sex-based segregation is present in most of the species’ known coastal feeding areas, with coastal sites typically dominated by juvenile male sharks. The largest known aggregation sites for Whale Sharks host hundreds or low thousands of individuals, based on counts and model estimates. Although individual sharks are highly mobile, many show a degree of site fidelity.
Directed fisheries and significant bycatch fisheries have targeted areas where high densities of Whale Sharks occur, leading to rapid reductions in catch per unit effort (CPUE) measures. Some bias toward juvenile Whale Shark-dominated aggregations are present in trend data; in the absence of information on other life-stages, these trends are inferred to be representative of population-level declines. While a number of commercial fisheries for the species closed during the 1990–2000s, Whale Shark products remain valuable and the species is still commonly caught in some countries. Serious injury and inferred mortality through vessel strike is a threat to several globally significant aggregations, as is bycatch in net fisheries, and the risk of ship strike. In the absence of conservation action, declines is likely to continue into the future.
Based on count data, modelled population estimates and habitat availability, 75% of the global Whale Shark population is inferred to occur in the Indo-Pacific, and 25% in the Atlantic. A variety of datasets present declines of 40-92%, inferring an overall decline of 63% in the Indo-Pacific over the last 75 years (three generations), resulting in a subpopulation assessment of Endangered A2bd+4bd. In the Atlantic, the overall population decline is considered to be lower at ≥30%, resulting in a subpopulation assessment of Vulnerable A2b+4b. Given the bulk of the global population occurs in the Indo-Pacific, the overall global decline is inferred to be ≥50%. Globally, the Whale Shark is therefore assessed as Endangered A2bd+4bd.
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