Kristin Rasmussen

Publications (2)4.22 Total impact

• Source

  Available from: Daniel M Palacios

  Article: Southern Hemisphere humpback whales wintering off Central America: insights from water temperature into the longest mammalian migration.

  Kristin Rasmussen, Daniel M Palacios, John Calambokidis, Marco T Saborío, Luciano Dalla Rosa, Eduardo R Secchi, Gretchen H Steiger, Judith M Allen, Gregory S Stone
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  ABSTRACT: We report on a wintering area off the Pacific coast of Central America for humpback whales (Megaptera novaeangliae) migrating from feeding areas off Antarctica. We document seven individuals, including a mother/calf pair, that made this migration (approx. 8300km), the longest movement undertaken by any mammal. Whales were observed as far north as 11 degrees N off Costa Rica, in an area also used by a boreal population during the opposite winter season, resulting in unique spatial overlap between Northern and Southern Hemisphere populations. The occurrence of such a northerly wintering area is coincident with the development of an equatorial tongue of cold water in the eastern South Pacific, a pattern that is repeated in the eastern South Atlantic. A survey of location and water temperature at the wintering areas worldwide indicates that they are found in warm waters (21.1-28.3 degrees C), irrespective of latitude. We contend that while availability of suitable reproductive habitat in the wintering areas is important at the fine scale, water temperature influences whale distribution at the basin scale. Calf development in warm water may lead to larger adult size and increased reproductive success, a strategy that supports the energy conservation hypothesis as a reason for migration.
  Biology letters 07/2007; 3(3):302-5. · 3.76 Impact Factor
• Source

  Available from: Laura J May-Collado

  Article: Patterns of cetacean sighting distribution in the Pacific exclusive economic zone of Costa Rica based on data collected from 1979-2001.

  Laura May-Collado, Tim Gerrodette, John Calambokidis, Kristin Rasmussen, Irena Sereg
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  ABSTRACT: Nineteen species of cetaceans (families Balaenopteridae, Kogiidae, Physeteridae, Ziphiidae and Delphinidae) occur in the Costa Rican Pacific Exclusive Economic Zone (EEZ). Based on data recorded from the EEZ by the Southwest Fisheries Service Center, Cascadia Research Collective, and CIMAR between 1979-2001, we mapped the distribution of 18 cetacean species. Our results suggest that the majority of the cetacean species use primarily oceanic waters, particularly those species within the families Balaenopteridae, Kogiidae. Physeteridae and Ziphiidae. Members of the family Delphinidae showed a wide variety of distribution patterns: seven species are widespread throughout the EEZ, four appear to be exclusively pelagic, and two are primarily coastal. Overall, three cetacean species appear to have populations concentrated in coastal waters: Stenella attenuata graffmani. Tursiops truncatus, and Megaptera novaeangliae. These three may be more susceptible to human activities due to the overlap of their ranges with fishery areas (tuna and artisanal fisheries), and an uncontrolled increase of touristic whale watching activities in several parts of their range. The distribution maps represent the first comprehensive representation of cetacean species that inhabit Costa Rican Pacific waters. They provide essential base-line information that may be used to initiate conservation and management efforts of the habitats where these animals reproduce and forage.
  Revista de biologia tropical 53(1-2):249-63. · 0.46 Impact Factor