Seasonal variation on diet of the narrownose smooth hound, Mustelus schmitti, Springer, 1939 (Chondrichthyes: Triakidae) from Puerto Quequen, Argentina

DÁVOLOS, J.; PEREZ, J. E.; PASTORINO, G; CAPPOZZO, H.L; CHIARAMONTE, G.

La Paz, México

Congreso; American Elasmobranch Society 16th Annual Meeting; 2000

American Elasmobranch Society

The narrownose smooth hound is an important economic resource for the coastal fleet at Quequén harbor (38° 37´S, 58° 50´ W). The aim of this study is to analyze the seasonal variation on diet for this species in the Puerto Quequén area. We studied 84 stomachs obtained from specimens captured by the trawl coastal fleet, between October 1998 and November 1999. We compared the diet among seasons and between sexes by Spearman correlation index, taking into account the frequency of each prey item. Winter season was not correlated with summer (rsc 0.38; p > 0.2), autumn (rsc 0.015 ; p > 0.5) and spring (rsc 0.33; p > 0.2). Diet was not correlated between sexes neither in spring (rsc 0.62; p > 0.05) nor in winter (rsc 0.85 p > 0.1). The most common prey item were crabs (Fo = 78.57 %), polychaetes (Fo = 96.43 %), and during spring season, bony fishes (Fo = 76.92 %). Our results showed that, as in other areas of the species distribution, Mustelus schmitti (the narrownose smooth hound) has a fundamental benthonic and carcinophagous diet, particularly during autumn and winter. During spring their diet includes Clupeids (v.g. anchovy, Engraulis anchoita) which are pelagic and neritic species. These results might be showing an opportunistic predator behavior in this species.