Initial study on catch, species composition and reproductive biology of fishes off the south‐west coast of Sri Lanka, targeted by ring nets while utilizing natural floating objects

Summary This study evaluates the catch rates, species composition and reproductive biology of flotsam-associated fishes targeted by ring nets off the southwest coast of Sri Lanka. Catch and number of multiday boats operating with ring nets were collected at Beruwala fishery harbor on the southwest coast of Sri Lanka, March to October 2013, by making fortnightly field visits. Fish samples were collected randomly from the unloaded ring net catches to analyze reproductive biology. Twelve fish species belonging to four major families: Scombridae, Carangidae, Coryphaenidae and Balistidae were identified in the ring net catches and five species, Decapterus russelli, Katsuwonus pelamis, Thunnus albacares, Elagatis bipinnulata and Canthidermis maculatus were predominant. An average of 25 ± 12% multiday boats landing at the Beruwala fishery harbor operated with ring nets each month, with an average monthly catch rate fluctuating from 730 ± 101 to 3924 ± 1094 kg per boat per trip. Catch rates of tunas and carangids were significantly higher than the other fish groups (anova; d.f. = 3, P < 0.05). Total fish landed by ring nets at the Beruwala fishery harbor during the study period was 1456 tonnes. Species belonging to the family carangidae had the highest percentage contribution (46.6%) to the ring net landings followed by tuna (34%). Similar-size individuals ranging from 24 to 31 cm were landed by ring nets, with all landed individuals belonging to K. pelamis, T. albacares and E. bipinnulata having immature gonads. The findings of this study will be useful locally as well as regionally to manage the ring net fishery and to aid in implementing measures to manage the highly migratory tuna species.