Standardized CPUE of Pacific saury (Cololabis saira) caught by the Korean’s stick-held dip net fishery up to 2022

Pacific saury (Cololabis saira) is widely distributed in the subarctic and subtropical areas of the North Pacific Ocean from the inshore waters of Japan and Kuril Islands eastward to the Gulf of Alaska and southward to Mexico (Parin 1960). The species migrates seasonally from the subtropical Kuroshio Current in winter to the Subarctic Oyashio Current in summer, for feeding on zooplankton (Shimizu et al. 2009, Taki 2011). The preferred water temperature for Pacific saury is 13-18 ℃, and the vertical distribution is from near-surface down to around 230m depth (Eschmeyer et al. 1983, Syah et al. 2016). The highest CPUE (catch per unit effort) of Pacific saury was found when the SST ranged from 14 to 16 ℃ (Tseng et al. 2013).

After the first exploratory stick-held dip net (SHDN) fishing from Korea had been conducted in the Northwest Pacific Ocean in the 1960s, three commercial fishing vessels commenced saury fishing in the area in 1985 (Jo 2003). Since then, the Korean stick-held dip net fishery has grown rapidly year-by-year, and the largest catch, 50 thousand tonnes, was made in 1997. Korea’s Pacific saury catch information has been managed by two organizations: Korea Overseas Fisheries Association (KOFA) and National Institute of Fisheries Science (NIFS). KOFA collected total catches and NIFS collects logbook data from fishing vessels as subsamples. The logbook contains daily catch and additional information such as light power (kw) and amount of catch by size (S, M, L, and 2L). However, since September 2015, an electronic reporting system (ERS) replaced the traditional logbook and has been collecting the catch data in near real-time. Accordingly, some of the data categories have been changed after the introduction of the ERS (e.g., the catches by fish size were unified into the total catch and light power information was excluded).