Investigations on Aimed Midwater Trawling for Myctophids in the Arabian Sea

Abstract

Aimed midwater trawling for lantern fishes (Family: Myctophidae) was attempted in the Arabian Sea onboard FORV Sagar Sampada (LOA 72.5 m; 2,285 hp) at the depth range of 372 - 2230 m using a 45 m CIFT myctophid trawl and 49.5 m krill trawl. The vertical opening was between 16.1 and 18.9 m at a trawling speed of 1.8-2.2 kn for the krill trawl and 6.7-9.8 m at 2.3-2.8 kn trawling speed for the myctophid trawl. Total catch obtained during operations was 419.5 kg for a total fishing effort of 33 h 41 min; with an overall mean catch rate of 11.81kg h-1. Myctophid trawl contributed 96.0 kg with a mean CPUE of 8.06±4.17 kg h-1 and krill trawl contributed 323.5 kg with a mean CPUE of 14.76±5.06 kg h-1. The total catch comprised of about 40 species including myctophids (24.88%), other finfishes (46.01%), crustaceans (15.21%), jellyfish (13.52%) and cephalopods (0.4%). Myctophids consisted of11 species and it contributed only 25% of the catch. Finfishes belonging to order Stomiformes contributed about 41% of the total catch. Adjustment of the trawl net to the depth of the fish distribution is complex as myctophids migrate vertically in morning and evening at comparatively high speed. The low catch volume realized during the operations, indicate that trawl design and its operation need to be further optimized taking into account the migration behavior in the vicinity of trawl system.