Martinho et al.: Comparative feeding ecology of two elasmobranch species, Squalus blainville and Scyliorhinus canicula 
81 
B 
100% • 
90% ■ 
80% ■ 
70% • 
5= 60% ■ 
3? 50% ■ 
40% • 
30% ■ 
20 % ■ 
10 % ■ 
0 % - — 
Adults 
| Teleostei 
[~| Mollusca 
□ Crustacea 
] Annelida 
El Others 
Juveniles 
Figure 7 
Seasonal variation in diet composition of Scyliorhinus canicula females according to the %IRI (% of the 
index of relative importance), separated according to the maturity stage for (A) winter 2006; (B) spring 
2006; (C) summer 2006; and (D) autumn 2006. The category “others” represents Echinodermata, Sipun- 
cula, Chondrichthyes, Uroehordata, and unidentified material. 
Table 4 
Seasonal Schoener index ( I s ) values for Scyliorhinus canicula , in a comparison of diet overlap between males and females by life 
stage: juvenile and adult. Values above 0.60 (marked with *) are considered a significant diet overlap, according to Wallace and 
Ramsey (1983). 
$ Adults 
9 Juveniles 
3 Adults 
3 Juveniles 
9 Adults 
3 Adults 
9 Juveniles 
3 Juveniles 
9 Adults 
^Juveniles 
3 Adults 
9 Juveniles 
Winter 2006 
0.60* 
0.31 
0.88* 
0.72* 
0.37 
0.55 
Spring 2006 
0.71* 
0.77* 
0.78* 
0.78* 
0.85* 
0.91* 
Summer 2006 
0.79* 
0.88* 
0.83* 
0.87* 
0.75* 
0.89* 
Autumn 2006 
0.86* 
0.85* 
0.89* 
0.83* 
0.76* 
0.85* 
and summer may also be linked to their reproductive 
cycles (see Capape, 1974), during which females may 
reduce feeding activity in favor of courtship and re- 
production. This lower feeding activity during higher 
reproductive activity was also observed by Capape et al. 
(2008) along the Mediterranean coast of France and by 
Craik (1978) for waters off the coast of England. This 
linkage between reproductive activity, feeding ecology, 
and differential habitat selection is therefore a critical 
issue for future research on elasmobranchs. 
Variation in feeding ecology of S. blainville 
and S. canicula along the Atlantic 
and Mediterranean waters 
When comparing the diet composition of S. blainville 
and S. canicula from the present results with diet com- 
position from other studies from the Mediterranean and 
Atlantic waters, several differences can be observed 
(Table 5). In general, Mollusca, Crustacea, and Teleostei 
were the most abundant prey items in the study by 
