Gonad indices, morphology and muscle fatty acid compositions of male and female golden mahseer (Tor putitora) sampled from lake Bhimtal (Himalaya) at different seasons of the year

Abstract

Adult male and female golden mahseer (n = 10–12) were collected during summer, monsoon, pre-winter and winter for evaluating gonadal seasonality, condition factor (CF), viscera-hepatosomatic index (VHSI), hepatocyte density (HD) and muscle fatty acid (FA) profile. In summer and monsoon, all males, but only 67% and 71% of females, were spawning capable in respective seasons. In pre-winter, males were mostly in regressing, but females were in regenerating phases. In winter, 50% of males and 14% of females were in the early spawning capable phase. VHSI and HD, in males only, were respectively highest and lowest in winter, indicating their nutrient recovery starting in pre-winter and completing in winter. Seasonal muscle FA profile of females only was linked to gonadal status, where C20:1, C22:1, C18:3n-6, C18:3n-3, C20:4n-3, C22:6n-3, total n-3 and n-6 FAs were depleted in peak spawning seasons. Overall, it was found that their spawning peak falls in summer and monsoon, but few early and late spawners were detected in winter and pre-winter, respectively. Males and females exhibited a different reproduction-linked nutrient allocation pattern; hepatic nutrient dynamic was prominent in males, but muscle FA dynamic was pronounced in females. CF dynamic was similar in both sexes.