User menu
Billfish represent three groups of species of marlins, sailfish and swordfish which can be considered as the third largest group of fish reported in large pelagic fish production in Sri Lanka. Being a by-catch in tuna longline fisheries, a deterministic role in the catchability of bill fish could be resulted from different bait types. This information would also be useful in exploring the potential to alter the catch in compliance with international obligations. The present study was based on logbook records of the Sri Lankan longline fishery from 2016 to 2019, with an aim of assessing the catch efficiency of bill fish species with respect to the bait types. During the period of study, it was noted that there were seven popular bait types; squid (Loligo spp.), bigeye scad (Selar crumenophthalmus), flying fish (family Exocoetidae), milkfish (Chanos chanos), Indian scad (Decapterus spp.), Sardine (Sardinella spp.) and artificial baits which represented 94.39 % in the fishery. Among those, squid was the most common bait while Sardinella spp. showed the least frequency in usage. Statistical analysis using Welch's analysis of variance (ANOVA) test for the catch rates of billfish have shown significant effects for different bait types. The longlines with Indian scad as a bait were reported with the highest average catch rate in terms of the number of fish per 1000 hooks: (4.0 ±2.6) followed by bigeye scad (3.7 ±2.3) while lowest was recorded with milk fish (2.6 ±2.1). The study revealed that there was a significant difference in the catch rates among different bait types (F (6) =534.17, p< 0.001) while Tukey's post-hoc test further revealed that the significance could be detected among the all combinations except for flying fish-artificial; squid-artificial and sardine-milk fish. The results further showed that the highest catch rates of swordfish, blue marlin and striped marlin were recorded for Indian scads while sailfish and black marlin for bigeye scad. This study highlights the importance of bait types in catchability of billfish and the findings could be used to manage tuna longline fisheries.
