M V Hanumantha Rao

Fishery, biology and stockassessment of spotted seer,Scomberomorus guttatus (Bloch& Schneider) off Andhra Pradesh

The fishery, biology and stock of the spotted seerfish, Scomberomorus guttatus (Bloch & Schneider) along Andhra Pradesh was studied during 2012-2014. The annual average landing of spotted seer during the period along Andhra coast was 2,614 t. Major contributors were trawlnets-1,104 t (42.2%) and gillnets-950 t (36.3%). Catches were higher during August-December. Length-weight relationship varied significantly between males, females and indeterminates. Growth was isometric in males and allometric in females and indeterminates. Overall sex ratio was 1:1.87. Length at first maturity was 38.9 cm. Peak spawning was observed during November-April. Higher Gonadosomatic index coincided with periods of peak spawning. Mature ovaries contained both maturing (0.41 mm-0.70 mm) and matured (0.71 mm-0.90 mm) ova. von Bertalanffy growth equation was Lt = 71.98 [1-e -0.23 (t + 0.0722)]. Natural mortality, fishing mortality and total mortality were 0.54, 0.49 and 1.03. Exploitation ratio was 0.48. Annual total stocks, biomass and Maximum Sustainable Yield were 8,546 t, 5,335 t and 2,747 t. A minor increase in yield and yield/recruit is possible by increasing the present level of fishing by 20%.

Fishery, reproductive biology and stock status of the Indian mackerel Rastrelliger kanagurta (Cuvier, 1817), landed along the north-east coastof India

The fishery, biology and stock status of Indian mackerel, Rastrelliger kanagurta (Cuvier, 1817), landed along the north-east coast was studied during 2011-2014. The average annual catch was 52,206 t. Catch was more or less equally contributed by trawlers, gillnetters and seiners with average catch rates of 3.05 kg h-1, 22.74 kg unit-1 and 140.09 kg unit-1 respectively. Catch was positively influenced by wind speed and negatively by sea surface temperature and precipitation. Growth in males was isometric, while it was allometric in females and indeterminates. Females outnumbered males in the commercial catches. Length at first maturity varied between 18.32 and 18.86 cm. Peak spawning season was during July - October and February - April. Relative fecundity was 567.51 ova per gram body weight. von Bertalanffy growth equation obtained was: Lt = 27.72 [1-e -1.2 (t + 0.023)]. Length at first capture and life span estimated were 12.78 cm and 2.48 years respectively. Natural mortality, fishing mortality and total mortality were 2.06, 3.69 and 5.75, respectively with an exploitation rate of 0.64. Peak recruitment was found to be during September-October. Maximum sustainable yield and yield per recruit were 40,675 t and 14.74 g respectively which were obtained by increasing the present fishing effort by 20%, but at the increased fishing effort, the increase in yield was a meager 0.53%, which indicates that the present level of fishing can be continued.