Humpback Whales: The Great Navigator in the Ocean
by Senzo Uchida
Humpback whales navigate a long distance of ocean in their migrations. In the summer months they feed the abundant food in the seas of the higher latitudes and in the winter descend on the warm waters of the lower latitudes to breed.
In summer in the North Pacific they fatten themselves in the rich seas of the Aleutians and Alaska. In the autumn some of them start traveling southward in the northwestern Pacific to Okinawa and Ogasawara, where they stay through the winter and spring.
Wintering in the warm waters, they come to breed and mate, and in late spring begin their journey to their feeding grounds in the north. Nursing their young calves, mother humpbacks swim northward as well.
The habit of staying close to the shore in both their breeding and feeding areas has been a cause of misfortune for the slow swimming humpbacks. These habits made it easy for them to be captured by small whaling boats using only simple hand thrown harpoons during former times when they were hunted. When the fleets modernized to harpoon guns, these whales were hunted indiscriminately to the brink of extinction.
The humpbacks that had traditionally migrated to Okinawa sharply decreased in population around the 1960's due to whaling in the Ryukyus and the northern seas. Finally in 1966 the total ban on whaling was instituted.
By the 1980's, about fifteen years after the whaling ban, the first signs of recovery for the population of humpbacks in the Okinawa waters could be seen. By 1990 there were enough whales to establish a number of whale watching tourist businesses that operate January through March in the seas off Okinawa.
In 1990 the Okinawa Expo Aquarium started the field research on whales with the grant of the Tokai Foundation on the population levels of humpback whales. This is the first long-term study on whales conducted in Japan.
Individual humpbacks can be identified by the patterns on their tail flukes. In the nine years since the beginning of the study 280 individuals have been identified.
The results of the survey since 1975 by the Okinawa Expo Aquarium showed twenty-six species of whales and dolphins distributed in the seas around Okinawa. Aside from the humpback whales, higher appearance rates of the southern species of whales and dolphins such as the Blainville's Beaked Whale, Melonhead Whale, Pigmy Killer Whale, and Roughtoothed Dolphin show the distinctive features of cetacean fauna.
There are excellent chances for humpback whale-watchers by chance to encounter Roughtoothed Dolphins, False Killer Whales, Risso's Dolphins, and Bridled Porpoises. A little farther off shore you can expect to see Sperm Whales as well.
Humpback whale-watching is currently centered on the Kerama Island group but should the migratory populations continue to increase there is the possibility of seeing the businesses expand to the tourist centers on the main island of Okinawa, the dream of many on the islands.
Dr. Senzo Uchida has been the director of the Okinawa Expo Aquarium since 1981. His study includes regional researches of humpback whales in the Aleutians in 1992 and 1995, and in Alaska in 1994 and 1995.