Humpback whales and other marine mammals off Costa Rica and surrounding waters, 1996-2003
Rasmussen, K., J. Calambokidis, and G.H. Steiger. 2004. Humpback whales and other marine mammals off Costa Rica and surrounding waters, 1996-2003. Report of the Oceanic Society 2002 field season in cooperation with Elderhostel volunteers. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 23pp
Since 1996, Cascadia Research has been conducting research on humpback whales and other marine mammals off the Pacific coast of Costa Rica and surrounding areas of Central America. In February 2003, we continued this research for the eighth field season in collaboration with the Oceanic Society and with Elderhostel volunteer support. 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 2003, and also includes some of the closely related effort we conducted after these trips in northern Costa Rica and Panama in both February and March. To make this report of broadest possible value, we also summarize the results from all eight years of research in this region and consider the significance of the findings in relation to our research off the west coast of the United States.
The primary effort in conjunction with Oceanic Society Expeditions, and Elderhostel volunteer support, consisted of boat surveys based from Drake Bay, Costa Rica for one week in 2003 (effort in 1996 to 2002 have ranged from one to four week-long programs each year). All of these have been conducted in January and February. 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 estimated to number about 8,000 (Calambokidis et al.1997, 2001). Humpback whales return annually to defined feeding areas in coastal waters, including the waters off California where about 700-1000 humpback whales return annually to feed (Calambokidis et al. 1996, 1999, 2002).
In the North Pacific, humpback whales were thought to use three primary wintering areas: the waters near Mexico, Hawaii, and Japan (Calambokidis et al 2001). It was not until research was conducted in the 1990s that it became clear that some humpback whales from the North Pacific were also using Costa Rican waters as a wintering ground (Calambokidis et al. 1997, 2000, 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 the annual return rate of animals to Costa Rican waters.
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.