Fishery, biology and stock structure of the King seer, Scomberomorus commerson off Andhra Pradesh

Abstract

The fishery, reproductive biology and stock structure of the king seerfish, Scomberomorus commerson (Lacepede, 1800) along Andhra Pradesh was studied during 2012 – 2014. An annual average catch of 3991 t was landed during 2012 – 2014. Gillnets were the chief contributor, contributing half of the landings, followed by hooks and lines (21.5 %), trawl nets (16.3 %) and seines (12.0 %). Growth was allometric with significant difference in growth rates between males, females and indeterminates. Overall sex ratio was 1:1.33. Length at sexual maturity was at a size of 62.5 cm. Mature females were observed round the year with a peak between September and March. Higher values of gonadosomatic index coincided with peak periods of spawning. Mature ovaries contained both maturing (0.7 mm to 0.9 mm in diameter) and mature (0.9 mm to 1.4 mm in diameter) ova. Sardine was the most preferred food item, followed by Stolephorus. Feeding intensity was very less, with high proportion of fishes exhibiting empty or trace amounts of food in stomach. Von Bertalanffy growth equation was Lt=173.2 [1-e -0.24 (t + 0.056)]. Bimodal recruitment pattern with recruitment occurring in all months was observed. Natural mortality, fishing mortality and total mortality were 0.43, 0.21 and 0.64 respectively. Exploitation rate was 0.33 and exploitation ratio was 0.16. Annual total Stock, Biomass and Maximum Sustainable Yield were 25731 t, 19005 t and 6082 t respectively. Marginal increase in yield and yield/recruit is possible by increasing the present level of fishing by 40%.