Bottlenose Dolphin (Tursiops truncatus) Predation on a Marine Fin Fish Farm: Some Underwater Observations

Publisher： European Association for Aquatic Mammals

ISSN： 0167-5427

Source： Aquatic Mammals, Vol.32, Iss.3, 2006-09, pp. : 305-310

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Abstract

This paper reports on the results of underwater observations of bottlenose dolphin feeding behaviour in a marine fin fish farm on the Sardinian coast in Italy from 2000 to 2005. During the study period, 178 underwater encounters were noted during 79 sightings of bottlenose dolphins at a fish farm. Total time spent underwater in the presence of dolphins was 284 min, with a mean encounter duration of 1.6 ± 1.3 min. Bottlenose dolphins were primarily observed hunting both schooling and solitary prey around the fish farm cages, using seven cooperative and individual feeding strategies throughout the water column. The underwater observations suggest that the use of different feeding strategies is consistent with the hypothesis that bottlenose dolphins apply common decision rules in relation to prey availability, resulting in the use of different foraging techniques. The observed frequency of the feeding strategies employed by dolphins preying directly on farmed fish could be worrisome for aquaculture.