The harbour porpoise is one of the smallest of all whale species, and inhabits many coastal areas in the Northern Hemisphere. It is abundant along all coasts of Denmark, with exception of the isle of Bornholm, where they are rare. An adult porpoise grows to lengths of 1.4-1.7 m and weighs 50-70 kg. The characteristic of the harbour porpoise is its small triangular shaped dorsal fin. The back is dark bluish or greyish and the belly is almost completely white. The harbour porpoise feeds on many fish species, and occasionally squids. It reaches sexual maturity at the age of 2-4 years, but seldom lives to be older than 20 years in the wild.