ABUNDANCE AND BIOLOGICAL INFORMATION ON TOOTHFISH IN DIVISION 58.4.4a & b BY SHINSEI MARU NO. 3 IN 2007/08 SEASON

A survey was conducted in order to collect information for the stock status and various biological information on toothfish in Division 58.4.4a & b by using a commercial bottom longline vessel, Shinsei Maru No. 3, from July 23 to September 27, 2008. The survey was undertaken in two Phases (Phase 1 and Phase 2). Shinsei Maru Trot line system was used as a fishing gear. Toothfish contributed 67-70 % in numerical number and 90-96 % in weight to the total samples in SSRUs. Mean CPUE of toothfish in number by SSRU ranged from 7.2 to 15.1 indiv. / 1,000 hooks and from 10.3 to 18.7 indiv. / 1,000 hooks for Phase 1 and Phase 2, respectively. Mean CPUE of toothfish in weight by SSRU ranged from 64.0 to 80.7 kg / 1,000 hooks and from 120.8 to 308.6 kg / 1,000 hooks for Phase 1 and Phase 2, respectively. Using a grid-based (10-minute latitude x 20-minute longitude) standard stratification method, mean CPUE for the Division was estimated to be 11.0 indiv. / 1,000 hooks and 108.8 kg / 1,000 hooks. With the possibly overestimated conversion factor between CPUEs of Trotline and Spanish line systems, the results of this survey suggest the recovery of the stock since 2000/01.