Bluefin tuna has been designated as one of the threatened species, according to IUCN. (Photo: WWF)
IUCN's listing of tuna as endangered refuted
Wednesday, October 19, 2011, 23:50 (GMT + 9)
The latest issue of the magazine Nanatsuno Umikara- from Seven Seas of the World has written an article denouncing the International Union for Conservation of Nature and Natural Resources’s (IUCN) criteria for determining which species are endangered. In its Red List of Threatened Species released in July, IUCN warns that tuna stocks must be replenished urgently and designated three (Atlantic bluefin tuna, southern bluefin tuna and bigeye tuna) of all eight tuna species as Threatened Species, and another two as Near Threatened Species.
To measure the magnitude of endangered status and classify into each category, the IUCN uses five criteria:
- Criterion A: drastic decline in the number of mature individuals;
- Criterion B: narrow distribution range;
- Criterion C: small population;
- Criterion D: especially small population, and;
- Criterion E: probability of extinction.
Criterion A, which uses the decline rate of individuals (decline speed), is problematic. With regard to Criteria B to D, the species are of extremely small size with a distribution range of 20,000 sqkm and the small population with the number of mature individuals at less than 10,000 at most.
Thus, considering the vast area of distribution with vast number of mature individuals of tunas, these criteria do not apply to southern bluefin tuna and Atlantic bluefin tuna.
Criterion A presents a problem for fishery resources because, if applied, very many resources would be qualified as Endangered Species.
While all other international tuna management organizations wish to attain the maximum sustainable yield (MSY), which happens when a species declines to half of its initial stock level, IUCN does not want this, as to IUCN it means that the species would be deemed as endangered.
“The inclusion of southern bluefin, Atlantic bluefin and bigeye tuna in the Red List this time represents a mistake caused by making a large overestimate of the extinction risk, as a result of ignoring the present stock size (which is still huge) and assessing only the stock size with the decline rate,” the article reads.
The IUCN should improve its criteria or revise their application, for example, by incorporating the current stock size into Criterion A. This would allow for the correction of the overestimation of endangered risk regarding the species whose stock size is known, the authors of the report suggest.
“There is no fear of extinction with regard to the tuna species that were included in the Red List this time. This is evident from the results of the stock management of the International Fisheries Committee related to tunas which uses a large amount of objective information,” the article added.
- 'Fake' list of endangered tuna, complain fisheries organization
By Natalia Real