Comprehensive study on the reproductive biology of black pomfret (Parastromateus niger) in the Bay of Bengal, Bangladesh

Abstract

Successful conservation, management and aquaculture development of fishery stocks require life-history data, especially for fish that have commercial importance. The black pomfret, Parastromateus niger is one of the commercially important fish species in the Bay of Bengal (BoB) and reproductive biological data are scarce to date. Therefore, to understand the reproductive biology of P. niger, a total of 101 males and 80 females were collected and the gonadosomatic index (GSI), length at maturity (Lm), fecundity and gonadal development were studied throughout the year (March 2018–February 2019). The highest levels of GSI were found from February–May with a second minor peak in October in both sexes. The Lm was calculated as 26.5 cm for males and 28.0 cm for females. The fecundity was found to vary from 114, 615 to 1, 227, 605 eggs with a mean value of 219, 433 eggs. The ovum diameter ranged from 28.32 ± 5.28μm to 285.53 ± 35.10μm with highest oocyte diameter in April when the fish reached full maturity, and the lowest in July (28.32 ± 5.28 μm) when new eggs began their development for the next spawning season. The maximum numbers of eggs in the ovaries were found at the yolk granule stage in February–May and also in October, which indicates that the ovaries develop to a peak leading up to the spawning season. A number of mature spermatids were also seen in males in the respective months with females. From these detailed observations, it may be concluded that P. niger shows two spawning peaks: in February–May and in October. The present study will provide a baseline for management ecology, conservation and aquaculture development for this highly valued fish species.