Fishery, biology and population characteristics of the Indian mackerel, Rastrelliger kanagurta (Cuvier) exploited along the Tuticorin coast

Abstract

Fishery and population characteristic of mackeral along the Tuticorin coast were studied during 1997-2007. The production of mackeral, exploited mainly by trawls and gillnets varied widely between 411 t and 2,038 t during the period. Fishery occurred round the year with peak abundance in June and August. Spawning as well as recruitment also occurred round the year with peak in January-April. Young ones start entering the fishery at a size of 6 cm in April every year. Growth parameters, Lα and K were estimated as 33.28 cm and 1.634 year-1 respectively. Natural mortality (M) estimated was 2.52. Total mortality (Z) varied between 6.04 and 11.85 and fishing mortality (F) between 3.52 and 9.33. The exploitation ratio (E) was in the range 0.582 - 0.787. The value of E max obtained (0.86) was lower than the exploitation rate throughout the period and MSY estimated (1,346 t) was higher than the average production during the period. Stock varied between 666 and 2,650 t and biomass between 99 and 365 t. The results showed that the fishery was largely based on the stock position and was independent of the effort. Since the species mature at an early age and spawn round the year, present fishing pattern appear to have no adverse impact on recruitment. Currently the resource is exploited near the optimum level and there appears to be no immediate threat for the stock.