More whales are getting entangled in fishing gear off the coast of California, experts said.
More than 150 entanglements were reported between 2015 and 2018, according to Karen Grimmer, resource protection coordinator at Monterey Bay National Marine Sanctuary. Grimmer and other conservationists presented research at an Aug. 15 joint advisory council meeting of the Greater Farallones and Monterey Bay National Marine Sanctuaries. The meeting was held at the Half Moon Bay Yacht Club.
“This is really an emerging issue,” said Point Blue Conservation senior marine ecologist Cotton Rockwood.
Researchers found that whales have been arriving in the area earlier in recent years, exposing them for longer periods of time to submerged crab pots. Fisheries are set to close earlier in 2020 to accommodate the whales, according to Rockwood.
Environmental issues may factor into the spike in entanglements. For example, entanglements surged in 2015 when crab season was delayed because authorities found high levels of toxic domoic acid in local crab. As a result, whales had to navigate fishing gear late into spring. Domoic acid levels may increase as ocean temperatures rise.
Grimmer, who is part of a working group that hopes to reduce entanglements while promoting a lively fishing industry, discussed tests for safer “ropeless” crab pots. However, Grimmer noted that tests have led to mixed results — one set of gear was lost in the ocean. Additionally, a “ropeless” crab pot may be three times as expensive as conventional gear.
“This will be a very iterative process,” Grimmer said.
One crabber appeared to hold her hands over her ears as Grimmer discussed the testing results.
The presentation also focused on whale-ship collisions. Rockwood and his team constructed a mechanistic model to simulate the incidence of collisions, because observed data for collision is limited.
Whales hit by ships rarely wash ashore, though at least four endangered whales have been stranded on beaches this year, according to Jessica Morten, a resource protection specialist contractor with Channel Islands National Marine Sanctuaries.
Rockwood highlighted two potential solutions to reduce collisions: convincing shipping companies to slow down their vessels and implementing speed reduction zones in areas with high concentrations of whales. He noted that his model predicted improved cooperation from companies and reduced speed limits could reduce mortality rates by about 30 percent.
In 2014, the Channel Islands Marine Sanctuary created an incentive program in which the sanctuary gives shipping companies grant funds and positive public relations in exchange for a promise that the companies will slow their ships in sensitive areas.
The program has scaled up to include 280 vessels and 46,026 nautical miles in 2018.