FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

In the past, the highest landings of the Loligo fishery in Taiwan reached 30,000 tons and the value of production reached 2.3 billion NT dollars in one year. However, the production has decreased dramatically in recent years, averaging less than one-third the catch of earlier years. This study focused on the age and growth of Uroteuthis (Photololigo) chinensis, U. (P.) duvauceli and U. (P.) edulis, which are the three major Loligo species in the waters around Taiwan. We hope the biological characteristics observed in this study will be helpful for the stock assessment of these resources. The results showed that the length-weight relationships differed between sexes for each species, and that such sexual dimorphism was significant for each species. The growth of the three species was fitted with power models and exponential models and the differences in slope and intercept among species were significant. The fastest growth was observed in U. (P.) chinensis, followed by U. (P.) edulis and U. (P.) duvauceli. The mantle length of mature individuals of U. (P.) chinensis and U. (P.) edulis were similar and were larger than 400 mm for males. The mantle lengths of U. (P.) duvauceli were smaller and the largest observed mantle length was 133 mm for females.