SEASIDE — Vacationers are not the only part-time residents of our region.
About 200 gray whales in the Pacific Coast feeding group return every year. Instead of migrating with the rest of the population north to the Bering Sea, they cavort for several months along Oregon’s coastline.
Known as resident whales, animals in the group do not live in the area year-round, according to Oregon State University graduate student Florence Sullivan at a lecture, “Inside Gray Whales,” presented by the North Coast Land Conservancy’s “Listening to the Land” series this month.
Sullivan is part of a research team for Geospatial Ecology of Marine Megafauna Laboratory, studying the gray whales that feed in the southern waters between Northern California and southeastern Alaska.
Sullivan noted that gray whales do not feed during migration, which makes the Oregon Coast an important habitat for them on their return to Alaska.
The focus of Sullivan’s research is to document the foraging behavior of the feeding group, the affect of man-made disturbances, overall health, body condition and the whales’ response to changing ocean conditions.
After the findings are completed, Sullivan works with local communities and whale-watching operators to create scientific guidelines for vessel operation in the presence of feeding gray whales.
The researchers’ viewing location is concentrated between Titchener Cove and Mill Rocks near Port Orford and Depoe Bay. The team uses a surveyor’s instrument called a theodolite to track and map the movement of individual whales as they forage. The data collected shows the whales’ traveling patterns between kelp beds, how they search for food and how they interact with vessels.
New research techniques such as GoPro cameras and aerial drones benefit the team to closely observe the whales’ patterns and behaviors, and hydrophones aid in recording the ocean noise — natural, human and mechanical — whales become exposed to.
In an effort to gain a better understanding of the foraging ecology of the gray whales’ feeding group, the team collects samples of a particular prey called mysid. Mysids are small, shrimp-like crustaceans found near the kelp beds.
“We think the reason they’re attracted to these foraging hotspots along the Oregon Coast is an abundance of mysid shrimp,” Sullivan said. “During summer months, the mysid can be really dense from the sea floor to the surface and really close to shore. We want to know if this wealth of foraging is enough to get these whales to disrupt their migration north, or is there some other mechanism that makes 200 whales act differently than the other 20,000? That’s what we hope to find out.”
Monitoring the activities of commercial, charter and recreational fishing boats, as well as whale-watching boats, can also determine the effects on whale behavior.
Sullivan pointed to a series of graphs and charts explaining how the data collected on vessel noise showed a significant disruption to the whale’s behavior patterns while traveling from one kelp bed to another, whereas there was little change to their behavior when actual foraging and eating was in process.
Photographing individual whales is another form of data collection. This allows the team to follow the whale’s migration patterns, their health and nutritional state. Aerial photographs allow the team to document breeding females with or without a new calf. This can also give the team an estimate of the number of calves produced each year, which is an important key of reproductive health and part of marine ecologist Leigh Torres’ research. Sullivan noted that photographing a gray whale involves multiple photos and a lot of patience.
“To identify gray whales, we need to take five photographs compared to one photo of the underside fluke of a humpback whale or one photo of the profile of a dorsal fin and saddle patch of an orca,” said Sullivan. To identify gray whales, researchers need to photograph the knuckle ridge along the back, underside of the fluke, both sides of the head and body showing scarring, barnacle patterns and mottling to make individual identification.