Fisheries biology of Indian squid (Loligo duvauceli) in west coast of the Gulf of Thailand

Nine loliginid species are found in Thai Waters, namely Sepioteuthis lessoniana, Loligo duvauceli, L. chinensis, L. singhalensis, L. edulis, L. beka, L. sumatrensis, L. edulis subsp. and Loliolus hardwickei, and other three squid species of Symplectoteuthis oualaniensis, Abraria armata and Thysanoteuthis rhombus. L. edulis subsp is found only in the Gulf of Thailand while L. edulis, L. beka and L. singhalensis are found only in the Andaman Sea. The distribution of L. duvauceli is all over the Gulf of Thailand at depth 10-50 m, the dense areas are in the western coast of the Gulf during January to March, July to September. The study on age and growth of the Indian squid using statoliths suggested the growth rate varied among individuals and sexes; male growth rate was higher than female; the life span was about one year or less; simple double exponential growth equations were proposed as male: Mlt=1.56e*[1.64. .180), female: Mlt=1.56 e*[1.35. .209). As the results of the present findings and the previous analyses. The squid regulution should be established more and the following proposals for squid management can be presented. 1) The squid light luring fishing gear should be reduced stepwise by about 20 percent of the present level mainly for preserving the spawners. 2) The existing fishing laws and regulations such as mesh size for capturing squid by light luring gears and fishing area within 3 km from shoreline of all types of fishing gear except non-motorized gears should be fully exhaustive. This measure is effective for preserving the squid recruitment. 3) During the period of closed area and season, 15 February to 15 May annually at Prachub Kiri Khan, Chumporn and Surat Thani provinces, the squid light luring fishing gears and prohibited stepwise from a large scale boat. It is suitable that the squid light luring fishing gear should be included in this regulation to preserve the spawners and juveniles, as they are exploited mixed with large squid abundantly in this period. 4) To decrease the fishing rate of light luring fishing gear, decrease of light intensity is effective with decrease of the number of fishing boat. It is possible that the intensity can be managed at the port and on the sea. 5) To make stock assessment of squid with high accuracy, it is required that fisheries statistics will be substantial, for example catch and effort record and it's report should be obliged at registration.