May 30, 2009

Japan increased cull limit of Steller's sea lions

Dear All

Japan again increased the cull limit of Steller sea lions.
http://d.hatena.ne.jp/hymatsuda/20070815
http://d.hatena.ne.jp/hymatsuda/20081007
In March and April 2009,
Potential biological removal (PBR) increased from 227 to 284 per year.
The cull limit increased from 120 to 144.

Several criticisms are expected.
0. Fortunately the Okhotsk population of Steller sea lions is gradually increasing. Therefore a stronger conservation effort may not be needed for population persistence.
1. However, there is no evidence that culling is effective to decrease fisheries damage by sea lions.
2. This population is listed Endangered by IUCN, but is listed as Vulnerable by Japan Ministry of Environment because of gradual increase.
3. Cull limit and PBR are determined and reviewed annually by Japan Fisheries Agency with scientific advisors. The above revision of PBR and cull limit is done without the meeting of scientific advisors.
4. PBR must include the number of cull and bycatch (removal by all human impacts). But the bycatch report is absent.
5. Sea lions that arrive at Japan coast is not a closed population. It may not be appropriate that Japan remove all PBR while Russia conserve the same population.
6. Japan assumed increase of the number of arriving sea lions because the total population size is more than the past estimate. There is no evidence that the number of arriving sea lions is proportional to the total population size.
7. Japan used the recovery factor (Fr=0.75) for calculating the PBR, where Fr should be 0.1 for Endangered species and 0.5 for Vulnerable species. There is no reason to use 0.75 for sea lions.

0 Comments:

Post a Comment

Subscribe to Post Comments [Atom]

<< Home