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International Journal of Marine Science 2014, Vol.4, No.46, 1-12
http://ijms.biopublisher.ca
4
Table 2 Index of Relative Importance of individual prey items in elasmobranch diet
Sr.No.
Prey items (Faunal group-wise)
Index of Relative Importance (%)
S. laticaudus
(N=71)
C. griseum
(N=42)
H. walga
(N=52)
I. Crustaceans
1.
Penaeus monodon
4.58
0.00
0.00
2.
Parapenaeopsis stylife
16.11
0.00
0.00
3.
Metapenaeus dobsoni
9.86
12.85
0.00
4.
Mysis
1.40
0.00
4.81
5.
Unidentified prawn
11.08
0.00
23.65
6.
Miyakea nepa
15.82
0.00
15.73
II. Teleosts
1.
Sardinella longiceps
12.83
71.03
0.00
2.
Stolephorus commerso
3.90
10.47
0.00
3.
Unidentified clupeid
3.45
0.00
0.00
4.
Trichiurus lepturus
3.93
0.00
0.00
5.
Unidentified teleost
10.52
0.00
0.00
III. Molluscs
1.
Uroteuthis duvauceli
0.00
0.00
55.79
2.
Sepiella inermis
6.47
5.63
0.00
Table 3 Diet matrix of
S. laticaudus
with prey items arranged in size groups indicating ontogenic shift
Sl. No.
Prey Items
Size Class
10
-
25
26
-
40
41
-
57
I.
Crustaceans
95.65
60.05
0.00
1
Penaeus monodon
0.00
12.78
0.00
2
Parapenaeopsis stylifera
17.39
0.00
0.00
3
Metapenaeus dobsoni
4.34
0.00
0.00
4
Mysis
39.13
0.00
0.00
5
Unidentified prawn
17.39
4.07
0.00
6
Miyakea nepa
17.39
43.19
0.00
II.
Teleosts
4.34
33.14
90.72
1
Sardinella longiceps
4.34
9.53
41.4
2
Stolephorus commersonnii
0.00
0.00
11.5859
3
Unidentified clupeid
0.00
9.53
0.00
4
Trichiurus lepturus
0.00
8.40
9.27
5
Unidentified teleost
0.00
5.66
28.45
III.
Molluscs
0.00
6.79
9.27
1
Uroteuthis duvauceli
0.00
0.00
0.00
2
Sepiella inermis
0.00
6.79
9.27
Levins’ diet breadth index (
B
) revealed that the all
three elasmobranchs
H. walga
(0.76),
S. laticaudus
(0.67) and
C. griseum
(0.53) are generalised feeder
which feeds on multiple prey items. Further,
estimation of diet overlap among these species
indicated the highest overlap between
S. laticaudus
and
H. walga
(65.61%), followed by
S. laticaudus
and
C. griseum
(34.00%). There was no overlap (0%)
between
C. griseum
and
H. walga
. The trophic level
of the elasmobranchs ranged between 3.75 (
C.
griseum
and
S. laticaudus
) and 4.05 (
H. walga
).
1.3 Catch trends (1969–2004)
Analysis of the elasmobranch annual catch landings of
Goa during 1969–2004 indicated highly variable
figures (461.78 ±363.33 mt), and their contribution to
the total marine fish landings of the region during
this period ranged between 0.05 and 5.04%.
Elasmobranch landings during the above period did
not show any particular trend (Figure 3). The initial
post-mechanization period (1969) was marked with
very low landings (138 mt), followed by a substantial