Porpoises and dolphins are often grouped together, as they are physically similar and behave in similar ways. However, they are not at all related apart from the fact that both are toothed whales. The harbour porpoise (Phocoena phocoena) is among the smallest of cetacean species. The average size of males is 1.5 m and 52 kg and females 1.6 m and 77 kg. The maximum size is about 2 m long and 90 kg. It is easily distinguished from the dolphins by its small size, oval shape and short nose. Porpoises are migratory like almost all other whales. It is rarely seen along the coast in winter but arrives early in the spring. Their diet consists mainly of small fish such as capelin, sandeels and redfish but porpoises are opportunistic feeders depending on food availability.