The St. Lawrence river in Canada has been identified as an area with very high biodiversity. (b) The St. Lawrence river is rich in species of aquatic mammals, especially whales. In spring, thousands of whales swim from the Atlantic ocean up the St. Lawrence river. Thirteen different species of whale have been recorded. One of these is the blue whale, Balaenoptera musculus. Fig. 1.1 is a diagram of a blue whale. dorsal fin [Figure 1.1] Photographs of blue whales are analysed by computer so that individual whales can be identified and population abundance can be estimated. Each blue whale is different in colour and in the shape of dorsal fin. Different whales also have different patterns of scarring.