Some biological characteristics of the smooth blaasop puffer fish Lagocephalus inermis (Temminck and Schlegel, 1850), from south-eastern Arabian Sea

Abstract

Length-weight relationship (LWR), condition factor, sex ratio, gonadosomatic index (GSI) hepatosomatic index (HSI) of the smooth blaasop puffer fish Lagocephalus inermis (Temminck and Schlegel, 1850), an emerging fishery resource along south-eastern Arabian Sea were studied from 1,722 samples collected during August 2017-May 2019 from Mangalore Fishing Harbour, Karnataka, India. LWR indicated negative allometric growth [W = 0.034805L2.76 (males); W = 0.033574L2.78 (females), W = 0.033979L2.77 (pooled)] and significant difference was observed in the b value of the fishes. Sex ratio was 1:1.08. The ratio was unusually high during post-monsoon and Chi-square test revealed that the monthly sex ratio did not vary significantly throughout the year except for December and January (p<0.01). Condition factor (K) and relative condition factor (Kn ) also were not significantly different between sexes. Two peak spawning seasons were identified - NovemberFebruary and August. The GSI was highest in August (female = 8.08 and male = 5.82) and lowest in May (female = 3.32 and male = 3.49). The HSI value was found to be inversely related to GSI and was highest in May (5.21) and lowest in August (3.99). These parameters are essential pre-requisites for stock assessment and sustainable management of the fishery resource.

Keywords: Arabian sea, Condition factor, Gonado-somatic index (GSI), Lagocephalus inermis, Length-weight relationship, Spawning