Basic HTML Version
International Journal of Marine Science 2014, Vol.4, No.46, 1-12
http://ijms.biopublisher.ca
6
Figure 6 Trends in landings of elasmobranchs, other higher
trophic level fishes and lower trophic level fishes of Goa (a)
during 1969–1979 and (b) during 1980–2004
weighing up to 250 kg were occasionally landed by
large mechanized vessels operating hook and line at
50–80 m depths. However, in recent times legislative
ban on hook-and-line fishing has probably reduced the
landings of these sharks. At present, these fishes are
rarely caught in purse seines.
2 Discussion
The present observations indicated that a total of 10
species represent Goan inshore fishing grounds.
Among these, only three species namely
S. laticaudus,
C. griseum
and
H. walga
were found to be more
frequent in their occurrence. Published literature
(Froese and Pauly, 2011) suggested that the above
species were the common inhabitants of estuarine and
inshore shelf waters across the Indo-Western Pacific
region. Further, the present study area along the west
coast of India is highly productive (Madhupratap et al.,
2001) and supports wide array of prey items
consisting of demersal teleosts and epibenthic
invertebrates (Ansari et al., 1995; Padate et al., 2010)
and is characterized by diverse habitats (Rao and Rao,
1974; Rodrigues et al., 1998), which provide suitable
niches to elasmobranchs. The observed frequency of
occurrence of these fishes in trawl catches indicated
that they were subjected to intensive fishing. Available
data on the fishing effort suggested that there has been
a considerable rise in the number of boats operating
along the Potential Fishing Zones (PFZ) in this region
(Department of Fisheries, Government of Goa, 2007;
Padate et al., 2009). It is mandatory to note that the
other seven species were rare in abundance and
occurred only in trawl catches operated in the vicinity
of submerged rock reefs. It is apparent that these
species preferred such habitats (Froese and Pauly,
2011) and stray individuals might have been
incidentally trapped in the trawl net. The inherent
biological traits such as slow growth and maturity, low
fecundity and slow doubling time (Hoenig and Gruber,
1990; Stevens et al., 2000; Frisk et al., 2005; Froese
and Pauly, 2011) might be the cause of their less
abundance in the tropical coastal waters. However,
higher elasmobranch diversity observed in the present
investigation, as compared to earlier published
literature (Prabhu and Dhawan, 1974; Ansari et al.,
1995), could be due to intensive trawl sampling
among varied habitats (estuaries, mangroves, submerged
rocky patches, coral reefs and nearshore waters).
Quantitative analysis of the trawl catches revealed that
the elasmobranchs contributed only 0.97% by weight,
which could be attributed to the capture of juveniles of
these organisms. The inshore fishing grounds off Goa
serve as the primary nursery areas for juveniles of
elasmobranchs (Ansari et al., 1995). Further, their
reduced abundance suggests that elasmobranchs
constitute an incidental by-catch of bottom trawlers
(mostly designed to catch demersal prawns and
ground fish), due to their ecological niche (Stobutzki
et al., 2001). A comparative analysis of the present
data with earlier reports (CMFRI, 1979; Kurup et al.,
1987; Srinath et al., 2006) suggested that in recent
years elasmobranchs’ contribution to the overall trawl
catches was distinctly less. This could be due to
increased fishing effort as evidenced by the number of
trawlers operating in this area, which are responsible
for indiscriminate removal of juveniles of these
species. Simultaneously, the data generated by the
CMFRI is mainly based on the landings from all