Documented Sighting of a North Pacific Right Whale in the Gulf of Alaska and Post-Sighting Acoustic Monitoring

Abstract

North Pacific whales lEubalaena japonica) are large whales (15 to 18 m in length) with a robust black body; narrow, high-arched upper jaw; no dorsal fin; and characteristic callosities on their rostrum and lower lips (see Rosenbaum and others 12000] for discussion of scientific names for whales). They are found in all oceans and migrate from hlgh latitude feeding grounds where they spend the summer to temperate waters for the winter (Braham and Rice 1984). They feed primarily on calanoid copepods by skimmingf' with their mouths open usually near the surface. They were given their name by whalers who considered them to be the right whales to catch because of their size and thick blubber layer, slow swimming speed, and the fact that they floated when killed (Braham and Rice 1984). The Gulf of Alaska was an important part of the summer distribution of the North Pacific whale before intensive whaling severely depleted the population (Rice 1974; Braham and Rice 1984; Webb 1988; Scarff 1991). A whaling ground that included the Gulf of Alaska (130° to 170°W) and waters south to 50° N, termed the Northwest or Kodiak Ground (Fig. 1), became a primary hunting area for whales after discovery there by pelagic whalers in 1835 (Townsend 1935; Scarff 1986) This discovery led to the widespread whaling of whales not only in the Gulf of Alaska, but throughout the North Pacific. The original population size for the North Pacific whale is unknown, but Scarff (2001) estimated a total whaling-induced mortality of 26,466 to 37,173 from 1835 to 1909. Almost half of these mortalities occurred in the 5-y period from 1845 to 1849 (Scarff 2001). The mortality dropped quickly for every 5-y period after 1849, with usually <100 taken per 5-y period after 1869. Their ecanomic value remained high, but only 20 whales were reported caught in the Northwest Ground between 1917 and 1935 (Reeves and others 1985; Brueggeman and others 1986). Tomilin (1957) reported that among 31J475 whales taken between 1911 and 1938 along the northwestern coast of North America only 28 were whales. In 1931, whaling nations, except Japan and the USSR, ratified a prohibition on the killing of whales made by the Convention br the Regulation of Whaling (Brownell and others 2001). Japan was restricted in the hunting of whales after World War II by the Supreme Commander for the A1lied Powers in 1945, and the USSR agreed to the prohibition when it joined the International Whaling Commission in 1945 (Brownell and others 2001). Although the whale was afforded protection in 1945J 251 illegal kills, 3 permitted kills, and fewer than 230 sightings have been documented from the Gulf of Alaska since that time (see Brownell and others [2001] for a review of all 20th century sightings and takes in the North Pacific). In 1961, 3 whales were taken on the same day off south Kodiak Island with a special permit to Japanese scientists (Omura and others 1969). Numbers of whales reported from scientific surveys conducted by the USSR in the western part of the Gulf of Alaska in 1959, from surveys throughout the Gulf of Alaska from 1960 to 1962, and in whaling records from 1958 to 1964 (Berzin and Rovnin 1966; Berzin and Doroshenko 1982) range from 88 to 200, due to discrepancies among reports (Brownell and others 2001). Xapanese whaling scoutboats and catcherboats reported a total of 26 whale sightings in the