Occurrence pattern of white-spotted conger larva, Conger myriaster, in the southern Tohoku area

Abstract

To reveal the occurrence pattern of white-spotted conger larvae (Conger myriaster) and its relationship to oceanographic conditions, we recorded daily changes in landings at a fish market and water temperature in southern Tohoku area from 1993 to 2002. Fishing season of larvae was from February to June, with its duration and peak fluctuating among years, corresponding to year-to-year variations in water temperature. Catch per unit effort (CPUE) of whitespotted conger larvae were approximately 0 at water temperatures <10 and ≤18°C in every year. Maximum and high values of CPUE occurred at 10–15°C. Leptocephalus larvae before metamorphosis occupied a greater proportion of the developmental stage compositions of samples collected before early April 2001 and 2002, whereas they scarcely appeared when the water temperatures were above 15°C after mid-April. It was concluded that the white-spotted conger larvae mainly immigrated into the southern Tohoku area at 10–15°C.