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.