Stomach contents of harbour porpoises, Phocoena phocoena (L.), from the Bay of Fundy

Abstract

We examined contents from stomachs of 127 harbour porpoises (Phocoena phocoena) caught in groundfish gill nets in the western Bay of Fundy during June to September, 1985–1987. Relative importance of prey species was assessed using both numerical and caloric measures. Atlantic herring (Clupea harengus) was the most important prey species, contributing 80% of the total caloric intake, with some spatial and temporal variation. Silver hake (Merluccius bilinearis) and Atlantic cod (Gadus morhua) were also important, but together comprised only 17% of the total caloric intake. No differences were found in relative prey importance between adult porpoises of different reproductive conditions, but lactating females ingested more fish and had a significantly higher total caloric intake than nonlactating females or mature males. The diet of porpoises collected from the same area in 1969–1972 consisted of a higher proportion of pelagic prey species and a lower proportion of demersal species. This may be attributed to differences in capture method, as the earlier sample of porpoises was collected at the surface, while the present animals were captured at depths of 45–100 m.