Distribution of white-spotted conger eel Conger myriaster and hagfish Eptatretus burgeri in the shallow region of Tokyo Bay [Japan]

This study describes distributions of white-spotted conger eel Conger myriaster as a main target species and hagfish Eptatretus burgeri as an incidental catch species for eel-tube fishery. In the shallow region of Tokyo Bay, young conger eels of total length smaller than 35 cm, which are called 'meso-anago' by fishermen, are caught and released because of their lower commercial value. For conger eel of marketable size, young conger eel and hagfish, daily catch per unit effort (CPUE, catch weight in kg per one tube gear) was obtained from the logbook of an eel-tube fishing boat during the period from 1994 to 2002, and stratified by the rectangles of 2' latitude by 2' longitude. The spatial distribution of monthly average value in the daily CPUE was analyzed. Young conger eels entered the eel-tube fishing ground in August and their bycatch started. Conger eels exceeding 35 cm total length began to be landed in November, and then dispersed over the whole fishing ground. While conger eels were distributed in almost the whole shallow region of Tokyo Bay, hagfish was concentrated in an area of over 30 m deep around the Nakanose shallow, the southwest area of the fishing ground, and its distribution seemed to be constrained by the salinity. Some other factors are also discussed.