Certain marine mammals, “large, iconic, charismatic animals” as referred to by Frances Gulland, commissioner of the United States Marine Mammal Commission, are facing extinction and protecting them will require political and economic support, Gulland and two other veterinary specialists said during a February 16 press briefing held at the 2020 AAAS Annual Meeting in Seattle.
“We can care about these animals as vets. We care about their welfare, their conservation,” Gulland said, “but unless there’s a political will to create laws and policies that are acceptable to commerce and the voting population, we aren’t succeeding.”
Gulland studies marine mammals who become beach-stranded all over the world to understand the diseases and human activities that may be impacting them. Her work, she said, involves assessing the health of individual animals, and translating that information both into how to protect the animal populations and also how to protect people from some of the same environmental contaminants and diseases affecting the animals.
Joseph Gaydos, science director of SeaDoc Society, the University of California, Davis School of Veterinary Medicine program, studies Southern Resident killer whales from Alaska to California. Only 73 of the animals remain, and so understanding threats to their survival and how to mitigate them is urgent, he said at the briefing.
Gaydos has been part of a project to analyze data on 20 years of carcasses to assess causes of death. A recent review of stranded killer whales showed they suffered not only from underwater vessel noise, which hampers their food foraging, and lack of food-source Chinook and other salmon as previously thought, but also from congenital diseases and human-caused incidents such as fishing line entanglement and vessel strikes.
“You’ll hear over and over in the news that these animals are starving,” Gaydos said, “but feeding an animal is not really a one-shot solution. There are a lot of problems that people don’t talk about, like traumatic boat strikes, congenital diseases, fisheries interactions where an animal will have a halibut hook in its stomach.”
After being listed in the United States as an endangered species 15 years ago, Gaydos said, more of the causes of their continued decline need to be addressed. Recent efforts in Washington state to slow ships down, keep whale-watching boats away from the animals, as well as expanding the salmon feeding supply, are ongoing and urgently needed, he said.
Off the East Coast of the United States, North Atlantic right whales are another highly endangered species, with only 400 individuals left. Michael Moore, senior scientist at the Woods Hole Oceanographic Institution, said avoiding extinction requires immediate changes. Entanglement in fishing lines is one of the leading threats to right whale survival, along with vessel strikes and underwater noise pollution. These perils have been exacerbated as climate change has moved the whale’s foraging habitat to include the Gulf of St. Lawrence because of a significant warming of the Gulf of Maine, endangering the whales themselves, as well as severely limiting their calving success, said Moore.
Pointing out that improving the whales’ foraging habitat in a short time is nearly impossible, Moore said protecting the whales from trauma can be accomplished by removing rope from the water to eliminate the entanglement they suffer, a threat he described at the briefing.
“[The whales] hit the gear, and they panic, and they roll, and they’re still trying to swim, but then they’re towing the gear,” which can include a string of lobster or crab traps, Moore said, pointing out that the entanglement is not only physical trauma, but also creates “drag” that is equal to being pregnant, with one result being that a female animal will not be able to calve.
One of the best options for eliminating the potentially entangling rope that connects fishing traps on the sea floor to a buoy on the surface is the adoption of acoustically managed buoyless trap systems. Visible on a fishing boat’s navigation system, the acoustically activated end of a row of traps will rise to the surface with the push of a button so the traps can be retrieved.
Fishing industry workers who have tested these ropeless methods believe they may be a workable solution – one that could benefit the whales and themselves. Using ropeless methods may reintroduce fishing into areas that have been closed off specifically because of the danger posed to whales by their sea-floor-to-surface ropes.
“The technology is enabling them back into closed areas, so there's an incentive,” said Moore, adding that government subsidies will also be required.
“We know so much already about these animals,” he added. “We know the right thing to do with these animals, and it’s nothing to do with science. It has to do with politics and economics.”
In addition to trying to stave off extinction of marine mammals, the scientists have also found ways to help protect human health through the study of the animals. For example, Gulland’s studies on sea lions may provide better information about what seafood is safe for pregnant women to eat.
Gulland and her collaborators are using MRI images of young sea lion brains to track potential behavioral changes resulting from domoic acid produced by red tides off the West Coast. Seafood with very high levels of domoic acid are already banned from commercial sale, but lower levels may still affect a developing fetus, sea lion or human.
[Associated image: Wesley/Adobe Stock]