“STUDIES ON THE FISHERY AND BIOLOGY OF OBTUSE BARRACUDA, SPHYRAENA OBTUSATA [CUVIER, 1829] ALONG MANGALURU AND MALPE COAST”
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Date
2021
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCE UNIVERSITY, BIDAR
Abstract
The obtuse barracuda, Sphyraena obtusata (Sphyraenidae), is a pelagic species found in
the tropical oceans around the world. It is a voracious feeder, feeding on fishes, crustaceans and
cephalopods. A total of 352 individuals of S. obtusata were analyzed which comprised of 162
males and 190 females. The comparison of different morphometric characters with total length
showed high values of correlation (0.708-0.985). Analysis of meristic characters indicated that the
number of spines on dorsal fin 1 (5), dorsal fin 2 (1), ventral fin (1) and anal fin (2) and number of
rays on dorsal fin 2 (9), ventral fin (5) and caudal fin (17) and number of gill rakers (2) on first gill
arch remained constant throughout the study. The length-weight relationships showed no
significant difference between male and female and thus a common equation derived for pooled
data was W = 0.01786 L2.6815 (r2 = 0.9658, n = 352). The value of relative condition factor (Kn)
varied from 1.00097 ± 0.04509 to 1.00153 ± 0.05640. Gut content analysis revealed that 118
stomachs (33.52 %) were empty and 234 stomachs (66.48%) contained food in varied quantity.
Index of relative importance (IRI) showed highest value for fishes (93.76%) followed by
crustaceans (6.09 %) and cephalopods (0.15%). The reproductive biology of S. obtusata revealed
that there are seven maturity stages in female and five maturity stages in male. The sex ratio skewed
towards females with an overall ratio of 1:1.17 (Male: Female). The spawning season of S. obtusata
was observed during September to December. The size at first maturity of male and female was
found to be 21.3 and 21.1 respectively. The absolute fecundity ranged from 91,942 to 1,34,445
with an average of 1,12,878 ± 2,763. The ova diameter ranged from 0.02 to 0.48 mm. The gonadosomatic
index (GSI) ranged from 1.23 ± 0.23 to 3.64 ± 0.98 for male and 1.31 ± 0.21 to 3.8 ± 0.39
for female. The proximate composition of S. obtusata showed 76.87 to 78.0 % moisture, 20.01%
to 21.39% protein, 0.82% to 1.21% fat and 0.92% to 1.19% ash.