Dr. Brad Hanson
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Whale Workshops and Symposia
Recent and Ongoing Research
SRKW Recovery Plan
2009 Southern Resident Killer Whale Research Update PDF
2007 Southern Resident Killer Whale Research Update PDF
2003 Southern Resident KillerWhale Newsletter (PDF |
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The Center's Marine Mammal Ecology Team conducts critical research on Southern Resident Killer Whales (SRKW) and other marine mammals in the Pacific Northwest. The team is led by Dr. Brad Hanson, and Drs. Dawn Noren and Marla Holt, and Candice Emmons are the group's other marine mammal scientists. Brad focuses on habitat and foraging ecology, Dawn specializes in marine mammal physiology and behavior, Marla works on marine mammal acoustics, and Candice provides assistance in all aspects of our research, particularly with her unique ability to identify each individual SRKW visually and each of the pods acoustically.
The Center's Marine Mammal Ecology Team works collaboratively with other scientists in the Conservation Biology Division's Genetics and Evolution Program, which studies the genetic structure of living marine resources, and the Mathematical Biology and Systems Monitoring Program, which studies population dynamics in relation to environmental parameters. The Marine Mammal Ecology Team also collaborates with scientists in the Environmental Conservation Division's Environmental Assessment Program, which investigates contaminant levels in marine mammal tissues and analyzes stable isotopes and fatty acids to understand marine mammal prey.
Winter 2013 Southern Resident Killer Whale Cruise
Southern Resident Killer Whale Satellite Tagging
2011 Southern Resident Killer Whale Research Update
Summary information on 2008 Southern Resident Killer Whale births and deaths
Satellite tagged Transient killer maps
2011 Recent Events:
The dynamics of persistent organic pollutant (POP) transfer from female dolphins to their offspring during gestation and lactation
Results of recent studies on Southern Resident killer whales demonstrate that they have high body burdens of persistent organic pollutants (POPs), namely PCBs and DDTs (Krahn et al. 2007, 2009). Most Southern Resident killer whales, including four juveniles, sampled exceeded the health-effects threshold for total PCBs in marine mammal blubber (Krahn et al. 2009). Because maternal transfer of contaminants to juveniles during rapid development of their biological systems may put these young whales at greater risk than adults for adverse health effects (e.g., immune and endocrine system dysfunction), it is important to understand the dynamics of POP transfer during gestation and lactation. There is limited information on the transfer of POPs from marine mammal females to their young during gestation and lactation, particularly for cetaceans (whales and dolphins). None of the previous studies on cetaceans have tracked how contaminant levels in mothers’ milk and in the blood of females and their calves change over the course of lactation. In order to fill this data gap, Dr. Dawn Noren is conducting a study in collaboration with the U.S. Navy Marine Mammal Program and scientists from NWFSC’s Environmental Assessment Program (Environmental Conservation Division) to concurrently measure POPs in milk and blood of bottlenose dolphin mother/calf pairs during lactation. Specifically, POPs (PCBs, PBDEs, DDTs, HCHs, and CHLDs) and lipid content are quantified in milk and blood serum collected from captive female bottlenose dolphins and their calves at four time intervals up to 15 months post-partum. POPs are also quantified in placentas from several females. Because maternal age and reproductive histories are known for all females, the researchers also hope to assess how these factors influence POP transfer dynamics from mothers to calves. These results will inform assessments of risk to delphinid calves, including killer whales, from POP exposure.
Krahn, M.M., Hanson, M.B., Baird, R.W., Boyer, R.H., Burrows, D.G., Emmons, C.K., Ford, J.K., Jones, L.L, Noren, D.P., Ross, P.S., Schorr, G.S., and Collier, T.K. 2007. Persistent organic pollutants and stable isotopes in biopsy samples (2004/2006) from Southern Resident killer whales. Marine Pollution Bulletin 54:1903-1911.
Krahn, M.M., Hanson, M.B., Schorr, G.S., Emmons, C.K.. Burrows, D.G., Burrows, D.G., Bolton, J.L., Baird, R.W., and Ylitalo, G.M. 2009. Effects of age, sex and reproductive status on persistent organic pollutant concentrations in “Southern Resident” killer whales. Marine Pollution Bulletin 58:1522-1529
Using DTAGs to study acoustics and behavior of Southern Resident killer whales
Drs. Marla Holt, Brad Hanson, and Candice Emmons of the NWFSC, along with collaborators from Cascadia Research Collective and UC Davis, are currently conducting a study using digital acoustic recording tags (DTAGs) to examine sound exposure, sound use and behavior of Southern Resident killer whales (SRKWs) in core summer habitat. The DTAG is suction cup attached and consists of a number of different sensors that record sound, pitch, roll, heading, and depth. The tag was developed by Woods Hole Oceanographic Institution specifically to monitor the behavior of marine mammals, and their response to sound, continuously throughout the dive cycle. Prey samples and vessel data are also concurrently collected relative to tagged whales in a manner similar to previous work (Giles and Cendak 2010, Hanson et al. 2010). The project research goals include: (1) measure noise levels in biological relevant frequency ranges that are received by individual SRKWs; (2) quantify the relationship between vessels and received noise levels; (3) determine acoustic behavior during different activities and matched with fine scale details on movement, especially those indicative of foraging; (4) quantify foraging efforts and determine potential effects of vessels and associated noise levels. The results of this study will provide pertinent data to address multiple risk factors of SRKWs including vessel disturbance, noise exposure, effects on foraging, and cumulative effects.
Metabolic costs of sound production and energetic effects of vocal responses to noise
Results of several recent studies including one conducted on killer whales by Holt et al. 2009 demonstrate that cetaceans respond to increases in environmental noise by increasing the amplitude, duration, and/or repetition rates of their acoustic signals. Potential energetic costs of vocal responses to noise have not been investigated in cetaceans. Drs. Marla Holt and Dawn Noren are conducting a study on the metabolic costs of sound production in bottlenose dolphins in Dr. Terrie William’s lab at UC Santa Cruz to study potential energetic effects of noise-induced vocal responses. In this study, metabolic rates are being measured in two trained bottlenose dolphins during periods of rest, vocal activity, and recovery. The dolphin’s are trained to produce either “loud” or “quiet” vocalizations on a given trial and results will be compared between the two conditions to determine if dolphins experience a metabolic cost when raising their voices. The results from this study will provide valuable data to address potential biological costs of anthropogenic noise exposure in cetaceans.
Ghost fishing impacts in Puget Sound
Since 2003, Marine Mammal and Seabird Ecology Team scientist Dr. Tom Good has been collaborating with the Northwest Straits Derelict Gear Removal Program (NWSC) project to understand the impact on marine wildlife posed by derelict fishing gear in Puget Sound and the Northwest Straits. These gillnets, along with pots, traps and other gear can entangle and kill animals, damage marine habitats, and pose navigation hazards long after being lost or abandoned. While these gillnets have long targeted Pacific salmon throughout Puget Sound, gear lost to the environment commonly contain many non-target species, including commercially valuable crabs, and fish, seabird and mammal species of conservation concern. One gillnet lost for a single week south of San Juan Island contained not only 25 of the targeted sockeye salmon, but 335 non-target fish, 68 crabs, and a harbor seal. Analysis of the 870 recovered gillnets detailed in a 2010 paper published in Marine Pollution Bulletin, documented at least 117 species and over 32,000 organisms 31,278 marine invertebrates, 1,036 fish, 514 birds, and 23 mammals entangled in the nets. For the vast majority of nets, the total time spent in the marine environment is unknown (but can range from weeks to decades), making it difficult to accurately determine how many organisms were killed over time. A “back-of-the-envelope” estimate suggests that the 870 recovered gillnets may have killed as many as 450,000 marine invertebrates, 12,000 fish, 12,000 marine birds, and 400 marine mammals. Dr. Good and colleagues at the NWFSC are continuing their analyses to model estimates of overall mortality over time.