Vol. 2, Issue 2 (2017)
Length-based population parameters of Indian Snapper, Lutjanus madras (Valenciennes 1831) off Madras coast along southeast coast of India
Author(s): Pradeep HD
Abstract: This study estimates some of the population parameters of Indian snapper, Lutjanus madras off Madras coast along southeast coast of India based on length-frequency data. A total of 776 specimens in the length range of 120-280 mm total length were collected from the trawl catches of the vessel M.F.V. Samudrika (OAL: 28.8m, GRT: 151T, BHP: 650) from January 2007 to June 2009 between the area Lat.12°30’ N to 13° 32’ N and Long. 80° 12’E to 80°30’E. The samples were also collected from Royapuram fish landing centre.The length frequencies collected were analysed with the help of electronic package FiSAT. The parameters L∞ and K were 294.0 mm, 0.52/year. The von Bertalanffy growth equation for L. madras is L = 294[1-e-0.52(t- t0 ) ]. The recruitment pattern is unimodal and the period of recruitment was from January to July with peak during April and May. The longevity of the species was calculated as 6 years. After 1st, 2nd, 3rd, 4th 5th and 6th year the length attained by the species is 119.2, 190.1, 232.2, 257.3, 272.2 and 281.0 mm respectively. The mortality parameters were Z=0.89, M =0.61, F=0.28 and the exploitation ratio was 0.32. The virtual population analysis for L. madras indicated that the natural morality due to natural cause was upto 140 mm mid-length, however the fishing pressure was observed at 160 mm size and it increased thereafter.