Zoological Studies

Vol. 46 No. 6, 2007

Geographical Distribution and Abundance of Pacific Saury, Cololabis saira (Brevoort) (Scomberesocidae), Fishing Stocks in the Northwestern Pacific in Relation to Sea Temperatures

Wen-Bin Huang1,*, Nancy C.H. Lo2, Tai-Sheng Chiu3, and Chih-Shin Chen4

1Graduate Institute of Biological Resources and Technology, National Hualien University of Education, Hualien 970, Taiwan
2Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA
3Institute of Zoology, National Taiwan University, Taipei 106, Taiwan
4Institute of Fishery Biology, National Taiwan University, Taipei 106, Taiwan

Wen-Bin Huang, Nancy C.H. Lo, Tai-Sheng Chiu, and Chih-Shin Chen (2007) We compared geographical distributions of Pacific saury, Cololabis saira (Brevoort) (Scomberesocidae), fishing stocks in the Northwest Pacific (NWP) for 3 yearly groups of high, average, and low abundances, using the Taiwanese fishery catch per unit effort (CPUE) data from 1994 to 2002. Two migratory groups, inshore and offshore, were found in averageand low-abundance years, while an additional oceanic migratory group, which spread eastward to around 178E in Oct., was found in the year of high abundance. Most of the saury groups were distributed in areas where the sea surface temperature (SST) ranged between 10 and 20C with a high aggregation around 15C, implying that 15C is the preferred temperature for saury to aggregate intensively for the commencement of the spawning migration, and to move southward to spawning grounds where SSTs of around 20C are favorable to their offspring. The timing, abundance, and geographical distributions of fish aggregations of migratory saury were associated with SSTs. In the early stages of the fishing season, apparent warming caused by the intrusion of Kuroshio Current waters in the southern NWP was closely related to delayed aggregation and low abundances of the saury stock; in contrast, cooling of the waters affected by Oyashio waters was related to eastward aggregation and high abundances of saury. High saury abundances occurred in low-temperature areas. Specifically, in years of low CPUE values, sea water temperatures (SWTs) of the fishing grounds were higher than 15C, while in years of average and high CPUE values, the SWTs of the fishing grounds were < 15C. Therefore, fishing ground SWTs higher than 15C (around 16C SST) is an indicator of low stock abundances of saury in the NWP.

Key words: Geographical information system, Sea surface temperature, Cololabis saira, Fishing ground, Taiwan.

*Correspondence: Tel: 886-3-8227106 ext. 2261. Fax: 886-3-8236935. E-mail:bruce@mail.nhlue.edu.tw