Oregon is lucky to have a distinct group of gray whales feed right off our coastline every summer and fall. Known as the Pacific Coast Feeding Group (PCFG), these gray whales use unique behaviors to feed, are shorter and skinnier than other gray whales, and use shallow, nearshore habitats that put them near a lot of human activity. It also makes for great opportunities to see and watch gray whales along our coastline both from shore and on the water during this time.
The majority of Eastern North Pacific (ENP) gray whales migrate from the Bering, Chukchi, and Beaufort Seas in the Arctic, where they feed on small crustaceans called amphipods that live in the bottom sediments, to lagoons in the Baja Peninsula of Mexico where they socialize and give birth to their young. This stock of whales was hunted to near extinction but is a conservation success story due to protections that allowed the population to recover, with a peak abundance estimate over 25,000 animals in 2016, which has also been estimated to be the carrying capacity for this population. By monitoring fluctuations in gray whale abundance, scientist have learned lessons about how this population is affected by climate. A series of unusual mortality events in the 1980s, 1990s, and again in 2019 to 2023, when many gray whales stranded in malnourished condition, was determined to be due to poor feeding conditions in the Arctic. The population estimate declined from 20,500 whales in 2019 to 14,526 whales in 2023. A 2023 study led by researchers at the Ocean Ecology Lab at Oregon State University’s Marine Mammal Institute (MMI) concluded that this gray whale population is experiencing major population swings because of climate change impacts on Arctic conditions.
The small group of about 200-250 gray whales known as the Pacific Coast Feeding Group (PCFG) use the waters from northern California to Vancouver Island, Canada to feed rather than going all the way up to the Arctic. These whales feed in shallow coastal waters less than about 66 feet (20 meters) targeting a variety of zooplankton prey. Tagging work by researchers at MMI provides information about movements and home ranges of PCFG whales tagged off the coast of Oregon and northern California. Whether the PCFG is a distinct population or part of the ENP population is currently somewhat ambiguous. There is evidence that the mitochondrial DNA, which is passed down from mothers to their offspring, of the PCFG differs from the ENP population, indicating that PCFG whales are taught to feed in this range by their mothers in what is called “vertical cultural knowledge”. In the U.S., the PCFG is recognized and reported on in stock assessment reports, but is not considered as a Distinct Population Segment under the Endangered Species Act or a separate stock under the Marine Mammal Protection Act. However, in Canada the PCFG was determined to be endangered by the Committee of the Status of Endangered Wildlife in Canada in 2017 and is under consideration for inclusion on its Species at Risk Act.
Many mysteries remain about the PCFG but, here in Oregon nearshore waters, innovative work by researchers at the Geospatial Ecology of Marine Megafauna Laboratory (GEMM) at the MMI is uncovering interesting findings about PCFG gray whales. Data collection methods in GEMM Lab research projects includes flying over these whales with drones to measure their body size and record behavior, listening to the noise in their habitat with hydrophones, scooping up their poop in nets, assessing their stress hormone levels, examining the caloric energy content of their prey and its availability, analyzing long term datasets, taking pictures to identify individuals and assess entanglement and boat strike rates, and using theodolites, GoPro cameras, tow nets, and kayaks. All this work and data has led to many discoveries, including:
- that individual PCFG whales utilize very specific tactics for feeding,
- that a decline in kelp health negatively impacted the zooplankton prey available to PCFG whales and their foraging time ,
- that the body condition of PCFG whales varies between years, months, and sex and age groups,
- that vessel traffic and its corresponding noise are positively correlated with stress hormones in PCFG whales (more vessels, more noise, higher stress),
- that when boats come within 100 yards, PCFG whales are likely to stop searching for food,
- that PCFG whales feeding off Oregon consume millions of microparticle pollution per day,
- that body condition of PCFG whales can differ from other gray whales that forage elsewhere in the same years, and
- that PCFG whales have gotten smaller since the year 2000 with female size being affected more than male size.
The GEMM lab has also learned a lot about the lives of individual whales that they see regularly, and you can read about their stories on the IndividuWhale website, including the whales “Clouds” and her calf “Cheetah” that bolster the concept of vertical cultural transmission being an important mechanism for the PCFG, or “Equal” whose propeller wound from a ship strike helped the GEMM lab learn about stress hormones. The GEMM lab has also produced vessel operation guidelines to help ensure that whale watchers in Oregon don’t disturb the whales. Work by the GEMM lab to better understand the PCFG is ongoing; you can keep up with their research and findings by following the GEMM Lab blog
