NWFSC researchers have returned from 10 days aboard the NOAA research vessel Bell M. Shimada following endangered Southern Resident killer whales (SRKW) off the coasts of Oregon and Washington. The researchers were extremely fortunate to have terrific weather, which contributed to the generous amount of data and information they were able to gather. This winter cruise addresses a high research priority to fill a major gap in our understanding of their life history- where these whales go during the winter, what they do, and what they eat.
Satellite tags reveal coastal distribution
Where do Southern Resident killer whales go when they leave Puget Sound? NWFSC scientists and their collaborators used location data from a satellite tag deployed on an adult male orca (K25) in late December 2012 to find out more about the winter migration of this endangered species and the extent of their range. The whales (K and L pods) were intercepted off Cape Blanco on March 2nd and were followed as they traveled and foraged up the Oregon and Washington coast. They were able to follow the whales up to near Cape Flattery before the shortened length of the cruise required they return to Newport, Oregon.
View NWFSC's maps and video that track the coastal movements of K25, the adult male orca tagged in December 2012.
Prey and fecal samples provide clues to killer whale diet
During the cruise the team was able to study K, L, and several groups of offshore eco-type killer whales. The team observed Southern Residents feeding on salmon on numerous occasions, answering a long-standing mystery on what SRKWs primarily feed on during the winter. Scientists were also surprised to observe offshore killer whales feeding on salmon, as there was previously no information on what this killer whale eco-type feeds on in Pacific Northwest waters.
Researchers collected 24 prey and 21 fecal samples, which once analyzed in the lab, will reveal the species, and likely the specific run, of salmon. Fecal samples also will be analyzed for measurements of stress and nutrition.
Monitoring killer whale sounds yields new information on their behavior
The acoustics team was able to significantly improve tracking methods using echolocation clicks detected on a towed hydrophone array and sonobuoys. This technology made it possible to track killer whales from farther away, acoustically "see" the gathering and splitting of groups, predict when the whales come to the surface, and count feeding events.
The researchers collected high quality recordings of offshore killer whales that will provide an opportunity to describe their calls and echolocation clicks and highlight differences between the offshore and SRKW vocal repertoire.
Ecosystem observations provide habitat information
While the cruise was well timed to observe how the whales utilize their habitat during the winter, it also allowed collection of related ecosystem data such as bird counts, zooplankton collections, and oceanographic information. These data provide key information that can lead to designation of critical habitat for these endangered animals.
As biological oceanographer and NWFSC senior scientist Bill Peterson says, "this is the time of year when the ocean is waking up." An example of remarkable ecosystem observations was the collection of hundreds of pteropods (a zooplankton species) off Newport, Oregon.
Another indication that we are learning a great deal of new information about the northern California Current ecosystem in the winter comes from results of marine bird surveys. Bird observers logged record numbers of parakeet auklets – over 2,100 individuals. Until these surveys, it was thought this diving seabird was only a rare and occasional visitor to waters off Washington, Oregon, and California. However, observations such as this lead us to believe these birds are regularly using the California Current during the winter. The California Current ecosystem likely provides important winter foraging habitat for not only killer whales, but also for other marine wildlife as well.
Tissue biopsies used to measure contaminant levels and identify family structure
Tissue biopsies were taken from the killer whales to yield information on the level of contaminants and their genetic stock structure (i.e., family relationships). The team collected a small amount of skin and blubber biopsy samples from nine whales—five from SRKWs and the other 4 from offshores. Contaminant levels help assess the health of the whales as well as make inferences about their diet. Skin samples will be used to genotype the whales which can be used in ongoing studies of family relationships and analyses of the stable isotopes in the skin can yield information on their winter diet.
As the team returned with the Bell M. Shimada to its homeport in Newport, OR Brad Hanson, Chief Scientist, was thrilled with the success of the cruise: "I am still in a bit of shock at the amount accomplished on this curtailed cruise." The duration of the cruise, originally scheduled for 21 days, was cut in half due to the recent Federal budget sequester.
Stay tuned for more information as the team begins to analyze their haul of information.
Southern Resident Killer Whale and Ecosystem Cruise: By the Numbers
- 10 Days at Sea
- 350 miles - distance travelled following the whales
- 12 Researchers from NOAA, Biowaves, and Cascadia Research Collective
- 24 prey samples (1 from an offshore type killer whale)
- 21 fecal samples
- 3 mucous samples
- 9 biopsies (5 Southern Resident and 4 offshores)
- 3 satellite tags (1 Southern Resident and 2 offshore)
- 7 standard oceanographic stations sampled
- Dozens of surface water samples for salinity productivity (chlorophyll), sea surface and water column temperature
- Continuous collection of echo sounder data