PORTLAND, Ore. (KOIN) – Researchers from a team led by Oregon State University have geographically located areas where whales are more likely to become entangled in fishing gear on the Oregon coast.
The research was recently published in a paper in the journal Biological Conservation and was a collaboration with scientists at the Oregon Department of Fish and Wildlife.
“We’ve also discovered that risk varies with time. It’s a very dynamic thing. And it varies with response to ocean conditions,” explained Solene Derville, a postdoctoral fellow at Oregon State University’s Marine Mammal Institute.
The university said the research is important because it provides better tools to manage fisheries.
The research for the study focused primarily on the Dungeness crab fishery, which is the most economically important in Oregon. The National Oceanic and Atmospheric Administration said commercial Dungeness crab pot gear is one of the most common types to ensnare whales along the West Coast in the United States.
In fact, in an effort to address whale entanglement concerns, ODFW adopted new regulations in 2020. Some key provisions of those rules end after the current Dungeness crab season.
After that, ODFW will consider the findings from this newly published paper as they evaluate the effectiveness of the regulations. In the fall, they’ll determine whether they’ll continue the regulations or adjust them for future seasons, according to Kelly Corbett, ODFW’s commercial crab project leader and a co-author of the paper.
Fishing gear entanglement is a major threat to whales. It can drown them or cause long-term injuries that affect their ability to eat, travel and reproduce. Researchers say documented whale entanglements have risen off the West Coast within the past decade.
“The more knowledge we have about when and where whales are, and how that overlaps with the fishery distribution, the better,” said Troy Buell, a state fishery management program leader for ODFW and co-author of the paper. “It helps us design more targeted management measures that are most effective for the whales, while having the least amount of impact on the fishery.”
For their research, scientists collected information through an eight-year period that ended in 2021. On average, according to NOAA data, 35 entanglements were reported each year along the West Coast of the U.S.
Scientists believe this is only a fraction of the actual number of entanglements that may have occurred but were never discovered or reported.
Scientists focused on humpback, fin and blue whales along the entire Oregon coast for the paper. They found that humpback whales were most often reported as entangled with Dungeness crab gear.
They then used previous research on whale density along the coast to predict where the whales were most likely to swim. This location information was then overlaid with data on Dungeness crab fishing locations to determine when and where the whales were most at risk of becoming tangled in the gear.
They found that entanglement was higher in water that was less than about 240 feet deep off Astoria, Garibaldi, north of Newport, north of Charleston, north of Port Orford and at Oregon’s southern border.
Whales were most likely to encounter the crabbing gear in April, researchers say, when whales typically gather in greater numbers closer to shore due to the onset of upwelling season. This is when colder, more nutrient-rich, deep water rises closer to the surface and shoreline due to winds. Whales like to feed on the krill that thrive when this water warms.
Scientists said exposure to crabbing gear remained constant until the end of crab season in nearshore waters and decreased past these depths. The exposure was also found to be lower during the marine heatwave event from 2014 to 2016, when fishing was more active near the shore.
Overall, the OSU researchers said fluctuations in the climate and ocean conditions, such as the upwelling events and marine heat waves, appear to be what increase the risk of whales becoming entangled in Dungeness fishing gear.
The scientists hope their findings will influence decision making by fishery managers.
“Although there can be inherent tension between commercial fishing and whale entanglements, no one wants to catch a whale and we all want a thriving, sustainable Dungeness crab fishery,” Torres said. “We feel our findings are an important step toward simultaneously achieving both these goals and relieving any tension.”