绪论 虎鲸类型和种群(第4/10 页)

th pacific

Research off the west coast of canada and the United States in the 1970s and 1980s identified the following three types:

Resident (fish-eating) orcas: the curved dorsal fins are typical of resident females.

Resident: these are the most monly sighted of the three populations in the coastal waters of the northeast pacific. Residents' diets consist primarily of fish and sometimes squid， and they live in plex and cohesive family groups called pods. Female residents characteristically have rounded dorsal fin tips that terminate in a sharp corner. they visit the same areas consistently. british columbia and washington resident populations are amongst the most intensively studied marine mammals anywhere in the world. Resident orcas can be divided into at least three distinct munities; northern， southern and southern Alaskan. Southern Alaskan resident orcas are distributed from southeastern Alaska to the Kodiak Archipelago and number over 700 individuals. these whales consist of two interbreeding clans distinguished by acoustic calls and whose ranges overlap. the northern resident munity lives in coastal and inland waters from southeastern Alaska to Vancouver Island. It consists of three clans and 16 pods and number over 300 orcas total. the southern resident munity generally inhabits the inland waters of southern british columbia and washington， but can be found in the outer waters off Vancouver Island， washington， oregon and california. they consist