Basic HTML Version
International Journal of Marine Science 2014, Vol.4, No.46, 1-12
http://ijms.biopublisher.ca
5
increase up to 1280 mt in 1979 (R = 0.898) and a
reduction up to 29 mt in 2000 (R = 0.786). However,
the production increased discernibly up to 1353 mt in
2004 (R = 0.999). Comparison of the above trends
with the annual marine landings of Goa revealed an
inverse relationship (Figure 3).
Figure 3 Landings of elasmobranchs and total marine fish
landings of Goa during 1969-2004
Although, data on the elasmobranch fishery of Goa is
available since 1969, assorted group-wise landings
data for sharks, skates and rays is available only for
the period 1981–2004. It is evident (Figure 4) that
sharks were the major group and their landing trends
influenced those of the total elasmobranchs during the
above period. Rays occurred largely as incidental
by-catch of bottom trawls and their contribution was
negligible except during 2002–2004 (Figure 4).
Figure 4 Catch trends of elasmobranchs including sharks,
skates and rays for Goa coast (1981–2004)
Further investigation into the causes of reduction in
elasmobranchs landings of Goa during 1969–2004
was done by comparing trends of their percentage
contribution to the total marine fish landings with
those of LTL and other HTL fishes. The graph (Figure
5) shows an inverse relationship between the trends of
elasmobranchs and other HTL fishes, whereas it
showed a direct relationship with LTL fishes. Hence,
the data were split into two periods i.e. the initial
period (1969–1979) with discernible increase in the
contribution of elasmobranchs (Figure 6 a) and the
later period (1979–2004) with gradual reduction
(Figure 6 b). The initial upsurge in elasmobranch
contribution (Figure 6b) was found to be noteworthy
(R = 0.932) and corresponded with concomitant
increase in other HTL fishes (R = 0.953) and
reduction in LTL fishes (R = 0.961). On the other hand,
reduction in the contributions of both elasmobranchs
and other HTL corresponded with negligible increase
in LTL percentage (Figure 6 b).
Figure 5 Trends in landings of elasmobranchs, other higher
trophic level fishes and lower trophic level fishes of Goa during
1969–2004
Elasmobranch landings data collected from two
principal jetties (Malim, North Goa and Betul, South
Goa) indicated that two species namely
S. zygaena
and
S. laticaudus
formed the major bulk of the sharks
landed at the respective jetties whereas,
C. griseum
was landed in meagre quantities along the entire
region.
It was further observed that the above species
were mainly caught by bottom trawlers operating
along the inshore waters between 20 and 80 m depths.
In addition, large pelagic sharks (
Carcharhinus
spp.)