INVESTIGADORES
BELLEGGIA Mauro
congresos y reuniones científicas
Título:
The diet of Mustelus schmitti; a comparison across decades
Autor/es:
BELLEGGIA MAURO; FIGUEROA DANIEL E.; SÁNCHEZ FELISA; BREMEC CLAUDIA
Reunión:
Congreso; World Congress of Herpetology; 2012
Institución organizadora:
American Society of Ichthyologist and Herpertologists (ASIH)
Resumen:
The diet of the narrownose smoothhound shark Mustelus schmitti was studied based on analysis of stomach contents from two disparate time periods from specimens on the northern Argentinean continental shelf (34 º S - 41 º S): The first set of specimens was collected from fifteen research cruises carried out by INIDEP from 1986-1994, total length ranged between 250-1050 mm. The second set of specimens was collected from eight research cruises from 2008-2011, total length ranged between 250-1050 mm. Prey items were identified to the lowest possible taxonomic level, counted and weighted. For comparisons, %IRI and the new %PSIRI were calculated. The hypothesis that the consumption of each prey group is determined by intrinsic (total length, sex, maturity) and extrinsic factors (region, season, period) was assessed by fitting generalized linear models (GLMs). Of the 1009 stomachs analyzed during the older period, 902 (89.39%) contained prey items. On the other hand, of a total of 959 stomachs sampled during the contemporary period, 944 (98.43%) contained food. Only the stomachs containing prey were analyzed further. The stomach contents of the narrownose smoothhound M. schmitti indicate opportunistic foraging behavior. The specimens caught between 1986 and 1994 fed mostly on Brachyura crustaceans (65.53%), followed by polychaetes (13.42%) and fishes (12.23%). The diet of those animals caught between 2008 and 2011 was composed mainly of polychaetes (38.12%) and Brachyura crustaceans (30.64%), followed by fishes (17.82%). Hermit crabs were rare during the older period (0.08%) but become more frequent during the recent years (7.38%). The trophic level is the position of an organism within the food web; it ranged between 3.76-3.92 during the older period and between 3.59-3.75 during the contemporary period.