BIO 227:7: Humpback Whales

Humpback Whales

Description and Ecology

Humpback whales, or Megaptera novaeangliae, are long, slender baleen whales with pointed snouts, two blowholes, and wide, flat heads known as their rostrum. On their heads they have bumpy protuberances called tubercles, and each has a bristle. And their dorsal fin is curved.The name “humpback” derives from the arching motion of their back when they prepare for a dive. With their beautiful songs (Check out National Geographic’s whale songs!) and acrobatics when breaching and slapping the water, Humpbacks are known as the performers of the ocean. They live in pods, usually consisting of 2-3 whales, but some pods have been sighted to be as large as 15 whales!

Humpback whales are found in all of the world's oceans, although they generally prefer near shore and near-island habitats for both feeding and breeding. A recent world population for the species was estimated to be around 60,000 individuals (6,000 - 8,000 in the North Pacific, 12,000 in the North Atlantic, and approximately 40,000 in the Southern Hemisphere) or about 30-35% of their original population before whaling, and can be divided into groups based on the regions in which they live. One group found in the North Pacific, in the waters off Alaska, is estimated to consist of about 2,000 individuals. A large percentage of this population migrates to the Hawaiian islands during the winter months, November through May, each year. The round-trip distance they travel during this annual migration is approximately 9,656 km, one of the longest migration distances of any animal species.

Geographic and Population Changes

Humpbacks had been heavily exploited by commercial whalers in the 1800s and early 1900s, which signficificantly reduced the global population. In 1946, commercial whaling of humpbacks was regulation by the International Convention for the Regulation of Whaling. Then, the International Whaling Commission ended commercial whaling of humpbacks in 1966.

Listing Date and Type of Listing

June 2nd, 1970 - Endangered

Cause of Listing and Main Threats to its Continued Existence

When U.S. Endangered Species Act was passed in 1973, humpback whales were classified as an endangered species. The cause was due to the significant impact of commercial whaling that had been happening for years.

Current threats to their existence include:

entanglement in fishing gear (bycatch)
ship strikes
whale watch harassment
habitat impacts
harvest

Description of Recovery Plan

The recovery plan for Humpback whales was written in November 1991 by the Humpback Whale Recovery Team. It had been approved by the National Marine Fisheries Service. This Plan concentrates primarily on populations of humpback whales believed to occur occasionally or permanently in the U.S. territorial waters of the North Atlantic and North Pacific Oceans. It summarizes current information on humpback whales, identifies problems that may interfere with recovery, and recommends research or management nations to restore and maintain the humpback whale as a viable member of the ecosystem. The “Recommended Recovery Actions” goals and objectives are:

Maintain and enhance habitats used by humpback whales currently or historically
Identify and reduce direct human-related injury and mortality
Measure and monitor key population parameters
Improve administrations and coordinations of recovery program for humpback whales