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FOOD AND FEEDING ECOLOGY OF THE COMMON DOLPHIN ( DELPHINUS DELPHIS ) IN THE OCEANIC NORTHEAST ATLANTIC AND COMPARISON WITH ITS DIET IN NERITIC AREAS
Author(s) -
Pusineri Claire,
Magnin Véronique,
Meynier Laureline,
Spitz Jérôme,
Hassani Sami,
Ridoux Vincent
Publication year - 2007
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2006.00088.x
Subject(s) - delphinus delphis , mesopelagic zone , predation , albacore , biology , foraging , thunnus , bay , cephalopod , capelin , ecology , fishery , habitat , tuna , oceanography , pelagic zone , fish <actinopterygii> , geology
The short‐beaked common dolphin, Delphinus delphis , is abundant in both neritic and oceanic habitats. These two domains differ largely in terms of the nature of forage organisms and their availability to surface‐bound top predators, which suggests that the common dolphin should show extensive variability in foraging strategies as a response to these different habitats. However, although its diet is well known over continental shelves, so far, mostly because of sampling issues, nothing has been published on its diet in oceanic habitats. In this study, the diet of sixty‐three common dolphins bycaught in the French albacore tuna driftnet fishery in the summers of 1992–1993 in the oceanic Bay of Biscay was determined from their stomach contents and compared to neritic studies. The diet was dominated by fish (90% by number [N] and 53% by mass of total diet [M]). Cephalopods were also important in the total diet (9%N, 46%M) but were a prey of secondary importance in the fresh fraction (3%N, 10%M), presumably due to longer retention of cephalopod remains in the stomach. Crustaceans were of minor importance. At the species level, the myctophid fish ( Notoscopelus kroeyeri ) largely dominated the diet. Prey size ranged from 1 to 68 cm, but the majority of preys were from 2 to 30 cm. The prey characteristics and their state of digestion suggest that the common dolphin forages preferentially on small schooling, vertically migrating mesopelagic fauna in the surface layer at dusk and early night. The diet is taxonomically distinct from results obtained in neritic studies but is similar in terms of prey type and the corresponding feeding behavior.