Seriolina nigrofasciata (Ruppel, 1829), its fishery and biological aspects off south-west coast of India

Abstract

A comprehensive study on fishery, length-weight relationship, trophodynamics and reproductive aspects of the blackbanded trevally Seriolina nigrofasciata (Ruppel, 1829), collected during January 2013 to December 2017 from fishing vessels operating along eastern Arabian Sea off south-west coast of India was conducted. Among the maritime states of the country, Karnataka was the major contributor (53.9%) followed by Kerala (24.1%), Maharashtra (16%) and Tamil Nadu (4.3%). In Karnataka, 99.5% of the blackbanded trevally catch was exploited by trawl net and rest by outboard gillnets (0.5%). The total length ranged from 16.3 to 57.5 cm with fishes in the size range of 24 to 36 cm forming 80.8% of the catch. The length-weight relationship estimated showed a negative allometric growth for both sexes with b values of 2.595 for females and 2.504 for males. The estimated ‘a’ values for females and males were 0.00013 and 0.00021 respectively. In all, fifteen prey items under three major groups (teleosts, cephalopods and crustaceans) comprised the diet, with teleosts (73.23%) being the predominant food item followed by cephalopods (26.53%) and crustaceans (0.24%) in terms of index of relative importance (IRI). Overall sex ratio (male: female) of 1:1.15 indicated a slight dominance of females over males. The length at first maturity was estimated at 25.0 cm for male and 27.0 cm for female. The availability of mature and spent specimens all through the year implied that the species has prolonged spawning period with a peak during the summer season (March-May) and a minor secondary peak in post-monsoon season (October to December).

Fishery and biological traits of obtuse barracuda Sphyraena obtusata (Cuvier, 1829) off south-west coast of India

“…Higher number of empty stomach is common in fishes which feed on other fishes (Juanes and Conover, 1994). In addition, the occurrence of high proportion of empty stomach could be attributed to the expulsion of food items during their struggle while they are trapped (Rajesh, et al, 2019) in trawl nets.…”

“…Early maturation of males compared to females in barracudas was reported earlier for Sphyraena chrysotaenia, S. flavicauda and S. sphyraena from Egyptian Mediterranean waters (Allam et al, 2004) and for S. putnamae from south-eastern Arabian Sea (Rajesh et al, 2020). Further, the longer time taken by the female fishes to mature could be related to the diversion of more energy for reproduction compensating the somatic growth (Miller and Kendall, 2009;Rajesh et al, 2019).…”

First report on the diet and reproductive biology of red-toothed triggerfishOdonus niger(Ruppell, 1836) from the south-eastern Arabian Sea

“…The stomach of each specimen was dissected and the stomach fullness recorded to evaluate the feeding intensity. The stomach fullness was visually classified into six categories (full, threequarters, half, quarter full, trace and empty) based on the presence of food (Rajesh et al, 2019). Further, the total length and wet weight of the gut was measured to the nearest 0.1 mm and 0.01 g respectively.…”