Preliminary estimation of seabird bycatch of Taiwanese longline fisheries in the Indian Ocean

Noting the increasing global attentions on the conservation of the ecosystem, the issue of incidental catches of ecological related species in fishing operations has been of great concerns. This is the first attempt to estimate seabird incidental catch of Taiwan longline fisheries in the Indian Ocean.
To collect scientific information for target species as well as incidental catch species, Taiwan has launched observer programs since 2002. There were 23 observer trips from 2002 to 2006 in the Indian Ocean large scale tuna longline fleets. The coverage rate by trips was 1.48% in average. The observed days were 1904. According to the data collected, the seabird incidental catch rate (BPUE) in each 5*5 degree grid square varied from 0 to 0.22 per 1000 hooks with the average BPUE of 0.048 per 1000 hooks. As for the seabird incidental catch distribution, the BPUE was the highest in the areas between 30-45 S and 25 W to 35 E and between 25-35 S and 65-95E. By using the total efforts data estimated from logbooks and the seabird BPUE from observers, the preliminary estimated average number of seabird incidental catch was around 1512 per year.