Dr. Gopalakrishnan, PDurai, VDr. Neethiselvan, NDr. Venkataramani, V.K2017-08-292017-08-292003http://krishikosh.egranth.ac.in/handle/1/5810029860A study on the selectivity and fishing pressure by six different hook sizes revealed the existence of notable selectivity by different hook sizes on six species of Lethrinus such as Lethrinus lentjan, L. mahsena, L. ramak, L. elongatus, L. conchyliatus and L. nebulosus. The peak fishing season of Lethrinus spp. in the long lines of Thoothukkudi coast was found to be from January to May. Fishermen of Thoothukkudi coast were found to use imported Mustad hooks of six different hook numbers. The use of correct type of baits such as lesser sardines and squid mantles following correct method of attachment were observed. The study revealed the dominance of L. lentjan in the fishery in the place of L. nebulosus reported by earlier workers during the period from 1985 to 1989 owing the use of multiple size hooks presently instead of hook No. 7 alone. Considering the hooking rate and length at first maturity, the optimum hook size for the commercial exploitation of L. lentjan, L. mahsena, L. ramak, L. elongatus, L. conchyliatus and L. nebulosus were found to be 11, 9, 10, 8, 8, and 7 respectively. The use of hook No. 12 may be discouraged in Thoothukkudi coast as it captured juveniles of all the six species studied. The study suggested to improve the design of the long line units of Thoothukkudi coast incorporating basic components such as sekiyama, swivel and snood wire in the branch lines.ennullThesis