Humpback whales and other marine mammals off Costa Rica, 1996-99

Citation

Calambokidis, J., K. Rasmussen, and G.H. Steiger. 1999. Humpback whales and other marine mammals off Costa Rica, 1996-99. Report on research during Oceanic Society Expeditions in 1998 in cooperation with Elderhostel volunteers. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501

Introduction

Cascadia Research in collaboration with Oceanic Society has conducted a long-term research effort on humpback whales and other marine mammals off the Pacific coast of Costa Rica. In January and February 1999, we continued this research with Elderhostel volunteer support. For the first time in 1999, we also conducted a separate research cruise sponsored by National Geographic using the 50' schooner Russamee surveying humpback whales from Mexico to Costa Rica and a suspected blue whale breeding area 500 miles offshore of Central America.

This report summarizes the research conducted on humpback whales and other marine mammals off southern Costa Rica as part of the Oceanic Society trips in 1999. We also summarize the results from all four years of research in this region and consider the significance of the findings in relation to our research off the west coast of the U.S. and our broader survey of Central America. Cascadia Research, in conjunction with Oceanic Society Expeditions, and Elderhostel volunteer support, has conducted surveys based from Drake Bay, Costa Rica for two to four week periods in January and February between 1996 and 1999. Until these studies began in 1996, little information was available on humpback whales and other marine mammals that inhabit the waters off the west coast of Costa Rica.

Humpback whales make seasonal migrations between high-latitude feeding areas and low latitude wintering areas where they mate and give birth to calves. Their populations were depleted by commercial whaling and in the North Pacific have recently been determined to number about 8,000 (Calambokidis et al. In Press). Humpback whales return annually to defined feeding areas in coastal waters, this includes the waters off California where about 900 humpback whales return annually to feed (Calambokidis et al. 1996a, 1999, In press).

In the North Pacific, they were thought to use three primary wintering areas: the waters near Mexico, Hawaii, and Japan. Within each of these three regions are a number of subareas. It was not until research conducted in the 1990s that it became clear that some humpback from the North Pacific were also using Costa Rica as a wintering ground (Calambokidis et al. 1996b, 1998, Steiger et al. 1991, Rasmussen et al. 1995, Acevedo and Smultea 1995). This research has provided some of the first information available about the number and behavior of humpback whales using Costa Rican waters.

The project has several scientific objectives:
1. Determine the number of whales using Costa Rican waters as a wintering area. 
2. Examine for evidence of whale preference for specific areas and habitats within the region. 
3. Determine the movement patterns and migratory destinations of these whales. 
4. Evaluate whether it is the same individuals that return annually to Costa Rican waters or if different animals use the area each year.
5. Further evaluate if humpback whales seen in Costa Rican waters are engaged in breeding behaviors similar to other North Pacific wintering grounds. 
6. Document the occurrence of other marine mammals in Pacific waters off Costa Rica including the habitats and regions that they inhabit.

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