Combining insights into reproduction and gear selectivity to enhance management advice for Encrasicholina heteroloba (Engraulidae) in the west coast of Sri Lanka

Abstract

Encrasicholina heteroloba belonging to the family Engraulidae is a commercially important fish species in the smallscale artisanal fisheries in Sri Lanka. Fishery, reproductive biology and gillnet selectivity pattern of E. heteroloba were assessed using the data collected from the Negombo fish landing site on the west coast of Sri Lanka from January to December 2015 in order to provide baseline information such as catch rate, total production, reproductive seasonality, size at first sexual maturity (L50) and gear selectivity pattern of this data poor fishery. E. heteroloba are mainly exploited using drift gillnets of 1.1 cm, 1.2 cm and 1.8 cm stretched mesh sizes. Females spawn throughout the year reporting a peak spawning in July. The sizes at first sexual maturity of E. heteroloba male and female are 7.40 cm and 7.45 cm, respectively. The gillnet selectivity study revealed that the optimum length (Lopt) and selection range of E. heteroloba varied with mesh sizes and estimated Lopt for 1.0 cm, 1.2 cm and 1.8 cm mesh sizes were 5.6 cm, 6.4 cm and 9.2 cm, respectively. We suggest to promote use of 1.8 cm mesh gill nets as a higher percentages of immature individuals are landed when smaller mesh (<1.2 cm) gill nets are used. The findings of this study will be useful to manage E. heteroloba stocks on the west coast of Sri Lanka.