Live-captures of common bottlenose dolphins <i>Tursiops truncatus</i> and unassessed bycatch in Cuban waters: evidence of sustainability found wanting
AbstractIn the period 1986-2004, 238 common bottlenose dolphins Tursiops truncatus were exported from Cuba, as shown by UNEP/WCMC data, more than 60% of these to facilities in Latin America and the Caribbean, some 32% to Europe and the rest to Canada and Israel. There is a very significant increase in exported numbers, reaching 28 individuals per annum in 2002. It is unclear how many T. truncatus have been used in domestic dolphinaria. A review of available information did not identify evidence to corroborate hypotheses that: (i) T. truncatus off Sabana-Camagüey Archipelago (where removals occur) does not show population structure; and (ii) virtually no bycatches occur in Cuban waters. Here it is argued that, considering Cuba's fully developed marine fisheries, some level of mortality from bycatch is inevitable. Other potential threats are also identified. Global phylogenetics research of T. truncatus is revealing unexpected and more complex, stock structures, in inshore (coastal) forms within relatively small areas. In Cuba, low mean group sizes (less than 10) suggest that one or more coastal stock(s) are exploited. Sex distribution of measured specimens suggest a significant bias towards extraction of females. It is concluded that sustainability of harvest levels of Cuban T. truncatus cannot be evaluated until abundance estimates become available and population structure is verified by molecular genetic methods. Pérez-Cao (2004) indicated that available density estimates should not be used to determine [safe] catch quotas. The authors strongly recommend that international trade of T. truncatus from Cuba ceases until no-detriment can be authenticated and that more research be developed. Similar arguments may be applicable to other unassessed but exploited populations in the Wider Caribbean.
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