A comparative analysis on the intensity of skipjack fishery by purse-seiners and pole and liners in the north-western Pacific ocean
1993
Shetty, D.C. (Tohoku National Fisheries Research Inst., Shiogama, Miyagi (Japan)) | Kawai, T. | Tanabe, T.
The present study, analyses the commercial catch records of the skipjack fishery by Purse-Seiners (PS) and Pole and Liners (PL) off the Pacific coast of Japan during 1987-1989 between 20-40N latitude and 120-150E Elongitude. The skipjack landings by these gear varied substantially both spatially and temporally. Although the fishery grounds of both the gears overlap, it is spatially separated at the beginning of the season. While the PS's catch of skipjack depends on the availability of tuna species, it's discernible to be independent for PL. According to the congregation of skipjack and as a consequence of their migratory habit three distinct zones and seasons were categorized from the south to the north of the region. Among the three years, maximum yields of skipjack were recorded in 1988 reaching a peak from June to early August. PL catch was greater than PS in each year. The survival rate of skipjack in the PS fishery rarely exceeded two periods (ten days period) unlike evident for PL. The fishing mortality coefficients and exploitation rates for individual schools of fish was significantly higher by PS than PL
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