engleski

Diet of the striped dolphin (Stenella coeruleoalba, Meyen, 1833) and interactions with fisheries in the Adriatic Sea

The striped dolphin (Cetacea: Odontoceti) is one of the frequently encountered cetacean species in the Adriatic Sea. This species feeds primarily on pelagic prey in deeper layers of the Mediterranean. However as only 26% of the Adriatic Sea is deeper then 200 meters, the deep-sea species are only present in the southern part. We hypothesised that the diet in the Adriatic would differ from Mediterranean data and have a closer relation to the bottlenose dolphin diet ; as two of the pelagic cephalopods found in bottlenose dolphins diet are among the most abundant pelagic cephalopods in the area. Interactions with trawling fisheries off the eastern Adriatic coast were also discussed. We examined stomach contents of 12 striped dolphins stranded along the Croatian coast in the period from 1990 until 2004. Stomachs of 8 individuals had food remains: undigested cephalopods, cephalopod beaks, fish bones and otoliths. Teuthoidea represented the most abundant prey, both in frequency and mass. Illex coindetii was the most frequent individual prey, with total mass estimated between 2200 and 2500 g. Loligo vulgaris could be ranked as second in importance, present in 50% of the stomachs. Both are common prey of the bottlenose dolphin, however there is a difference in the size of consumed Illex coindetii and no differences in the size of consumed Loligo vulgaris (Mann-Whitney U-test, P=0.05). As Loligo specimens of 200 g and over are exploited by commercial fisheries, it is suggested that smaller specimens (<200 g) are more abundant and consequently the same size is consumed by both dolphin species. We concluded that the diet could be characterised as opportunistic, but fishing could have an impact that should be assessed in fisheries management plans.

striped dolphin; diet; cephalopods

nije evidentirano