Mission, Vision, Goals
Studies on cetacean behavior provide information on social organization and structure, social signals, mating systems and anthropogenic impacts. The goal of these studies is to provide a social framework within which to investigate questions about stock identity, population trends and fishery interactions. The cetacean behavior studies reflect the interests and expertise of many researchers in the Protected Resources Division. We use a variety of tools and work in collaboration on a number of different questions related to sociality in the open ocean.
Male eastern spinner dolphin showing sexually dimorphic dorsal fin, post-anal keel and flukes (photo: Bob Pitman)
Cetacean Social Structure
Within the Molecular Ecology Laboratory, researchers are working on a number of case studies that use molecular genetic techniques to document the social organization, social structure and sex-biased dispersal patterns of wild cetaceans. There are on-going studies on several species, including sperm whales, Dall's porpoises, eastern tropical Pacific dolphins, belugas, killer whales, pilot whales, and gray whales.
Cetacean Mating Systems, Sexual Dimorphism and Sperm Competition
We are working on comparative studies of cetacean mating systems based on relative testes sizes and sexually dimorphic characters. We are interested in both intraspecific variation in mating systems (spinner dolphins, with Bill Perrin) and interspecific variation (comparative studies of the odontocete cetaceans; in collaboration with the San Diego Zoo's Conservation and Research for Endangered Species Center.)
Anthropogenic Impacts on Eastern Tropical Pacific Dolphin Behavior
We are studying variation in dolphin behavior in several stocks of eastern tropical Pacific dolphins involved in the tuna purse-seine fishery (with Eric Archer). In these studies, we are interested in the application of new (Random Forest) statistical methods to determine predictors of dolphin behavior and the potential impacts of social disruption (caused by the reaction of individual dolphins and of dolphin schools to fishing operations) on the ability of dolphins to reproduce as expected.
Group of eastern tropical Pacific killer whales (photo: Holly Fearnbach)
Biogeographic Variation in Cetacean Acoustic Signals
We are interested in biogeographic variation in social signals (primarily acoustic) and the use of acoustic signals as indicators of population identity. This project is in collaboration with John Hildebrand at Scripps Institution of Oceanography and Mark McDonald at Whaleacoustics. Most recently, the collaboration investigated hypotheses to explain the decrease in pitch of blue whale song globally.
Behavioral Ecology of Killer Whales
We are collaborating with the Ecosystem Studies Program in investigations of killer whale behavior, ecology and evolution and how the risk of predation by mammal eating killer whales influences the behavior and ecology of other cetacean species. In the eastern tropical Pacific, we are investigating the genetic structure of groups.
For questions about the Cetacean Behavior studies, please contact: Sarah Mesnick
McDonald, M.A., Hildebrand, J.A. and Mesnick, S.L. In press. Worldwide decline in tonal frequencies of blue whale songs. Endangered Species Research.
Mesnick, S.L. and Ralls, K. 2008. Mating Systems. In, Encyclopedia of Marine Mammals, Second Edition (eds., W.F. Perrrin, H.G.M. Thewissen and B. Würsig). Academic Press, San Diego. Pages 712-719.
Ralls, K. and Mesnick, S.L. 2008. Sexual Dimorphism. In, Encyclopedia of Marine Mammals, Second Edition (eds., W.F. Perrrin, H.G.M. Thewissen and B. Würsig). Academic Press, San Diego. Pages 1005 – 1011.
Rubio-Cisneros, N.., Mesnick, S.L., Vázquez-Juárez, R.., Urbán-Ramírez, J., Godard, C.A.J., Payne, R.. and Dizon, A.E. 2007. Genetic sex determination supports the Gulf of California as an important habitat for male and female sperm whales (Physeter macrocephalus). Latin American Journal of Aquatic Mammals 5(2): 125-128.
McDonald, M.A., Mesnick, S.L. and Hildebrand, J.A. 2006. Biogeographic characterization of blue whale song worldwide: using song to identify populations. Journal of Cetacean Research and Management 8: 55-65.
Allen, A., Mesnick, S.L., Anderson, M., and Dixson, A. 2003. Phylogenetic analysis of testes size in odontocete cetaceans. Abstract presented at the 15th Biennial Conference of the Marine Mammal Society. Greensboro, North Carolina, December 2003.
Bonness, D., Clapham, P.J. and Mesnick, S.L. 2002. Life History and Reproductive Strategies. In,Marine Mammals: An Evolutionary Approach (ed., R. Hoelzel).Blackwell Science, Ltd. Pp. 278-324.
Escorza-Trevino, S., and A.E. Dizon. 2000. Phylogeography, intraspecific structure, and sex-biased dispersal of Dall's porpoise, Phocoenoides dalli, revealed by mitochondrial and microsatellite DNA analysis. Molecular Ecology 9:1049-1060.
Mesnick, S.L., Evans, K. Taylor, B.L., Hyde, J., Escorza-Trevino, S and Dizon, A.E. 2003. Sperm Whale Social Structure: Why it Takes a Village to Raise a Child. Pages 170-174, In, Animal Social Complexity: Intelligence, Culture and Individualized Societies (F.B.M. de Waal and P.L. Tyack, eds.). Harvard University Press
Mesnick, S.L. 2001. Genetic Relatedness in Sperm Whales: Evidence and Cultural Implications. Behavior and Brain Science 24(2):346-347
Mesnick, S.L., Clapham, P.J. and Dizon, A.E. 1999. The Collection of Associated Behavioral Data with Biopsy Samples during Cetacean Assessment Cruises. Journal of Cetacean Research and Management 1(2): 205-211
Mesnick, S. L., Taylor, B.L., Le Duc, R.G., Escorza Trevino, S., O'Corry-Crowe, G.M. and Dizon, A.E. 1999. Culture and Genetic Evolution in Whales. Science, 284: 2055a
O'Corry-Crowe GM, Suydam RS, Rosenberg A et al. (1997) Phylogeography, population structure and dispersal patterns of the beluga whale Delphinapterus leucas in the western Nearctic revealed by mitochondrial DNA. Molecular Ecology, 6, 955-970.
Perrin, W.F. and Mesnick, S.L. 2003. Sexual ecology of the spinner dolphin, Stenella longirostris:, geographic variation in mating system. Marine Mammal Science, 19(3):462-483
Pitman, R.L. 2003. Good whale hunting. Natural History December 2003/January 2004:24-28
Pitman, R.L., S. O'Sullivan, and B. Mase. In Press. Killer whales (Orcinus orca) attack a school of pantropical spotted dolphins (Stenella attenuata) in the Gulf of Mexico. Aquatic Mammals.
Pitman, R.L. and P. Ensor. 2003. Three different forms of killer whales in Antarctic waters. Journal of Cetacean Research and Management 5(2):131-139
Pitman, R.L., Ballance, L.T., Mesnick, S.L. and Chivers, S. 2001. Killer Whale Predation on Sperm Whales: Observations and Implications for Large Whale Biology. Marine Mammal Science: 17(3):494-507.
Pitman, R.L. and S.J. Chivers. 1998/1999. Terror in black and white. Natural History 107:26-29.