Dr. Michael Ford
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2003 Southern Resident KillerWhale Newsletter (PDF |
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The Center's Marine Mammal Program conducts critical research on Southern Resident killer whales and is led by Dr. Michael Ford. Drs. Brad Hanson and Dawn Noren are the program's two marine mammal scientists. Brad is an expert on habitat and foraging ecology, while Dawn specializes in marine mammal physiology. The Center's program also includes scientists from the Center's Environmental Assessment program, which measures contaminant levels in marine mammal tissues and analyzes stable isotopes and fatty acids to understand marine mammal prey, and the Genetics program, which studies the genetic structure of living marine resources.
2007 Southern Resident Killer Whale Research Update
Summary information on 2008 Southern Resident Killer Whale births and deaths
Satellite tagged Transient killer maps
Recent Events:
Research on prey preferences and distribution
In summer 2008, Marine Mammal Program scientists, in collaboration with partners from the
Center for Whale Research and
Cascadia Research, continued field studies on the prey preferences of southern resident killer whales, including the use of genetic analysis of prey remains and fecal samples to identify the species and in some cases stocks of fish the whales are eating. Other projects included new analysis of the caloric requirements of resident killer whales, and satellite tagging of transient killer whales. More information on the satellite tagging and prey studies can be found on the Cascadia Research web site.
Speaking up: killer whales compensate for vessel noise
Given their dependence on sound and the many anthropogenic sources of noise in their core habitat, concerns have been raised about acoustic impacts on Southern Resident killer whales. For example, noise can mask or cover up the calls killer whales produce making it harder for them to use these sounds to communicate with group members who forage cooperatively. A study by NRC postdoctoral researcher, Dr. Marla Holt, and collaborators including NWFSC, Colorado College and Beamreach researchers have found that Southern Residents compensate for the masking effects of vessel noise by calling louder. In a new article (in press) in JASA Express Letters, "Speaking up: killer whales compensate for vessel noise," these researchers show that whales increase their call level by one decibel for every decibel increase in background noise levels. Since calls are used for communication, it is not surprising that whales call louder when background noise levels are raised. Such a vocal response is called the "Lombard effect", and people, birds and evidently, killer whales do this. The researchers also report that noise levels increase as the number of motorized vessels around the whales increases, illustrating the contribution vessel traffic has to background noise levels in the whales’ underwater environment. Even if the whales can raise their voices when many vessels are present, there might be costs associated with that or at some level, vessel noise could completely mask their calls. In this case, the range over which whales can communicate with one another significantly decreases which may limit the extent to which they are able disperse to find food.
NWFSC postdoctoral researcher Marla Holt measuring the sound levels of killer whale
calls near San Juan Island. |
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