A new study by researchers at Oregon State University’s Marine Mammal Institute suggests most entanglements of Steller sea lions in human-made marine debris along the Pacific coast could be prevented through education and changes to manufacturing and packaging processes when the entangling materials are produced.
In the first study of its kind in the Pacific Northwest, Kim Raum-Suryan, an OSU faculty research assistant, studied Steller sea lions between 2005 and 2009 at two of Oregon’s most iconic locations, the Sea Lion Caves and Cascade Head. Steller sea lions use these as “haul-outs,” places where the mammals rest on land between feeding forays.
Over the past 30 years, the Steller sea lion population has declined by more than 80 percent, resulting in its threatened status in the eastern portion of its range (central California to southeast Alaska) and endangered status in the western portion (western Alaska).
During the study, which was completed with funding from Oregon Sea Grant, Raum-Suryan witnessed 72 animals entangled in debris including: black rubber bands used on crab pots; hard plastic packing bands used around cardboard bait boxes (and other cardboard shipping boxes); and hooks and other fishing gear.
Since 2000, the Alaska Department of Fish and Game has recorded more than 500 Steller sea lions in Alaska and northern British Columbia that have either become entangled in marine debris or have ingested fishing gear.
“There are likely many more entangled animals from Alaska to the central California coast that are not observed because entanglement can lead to death by drowning, infection or starvation before the sea lions ever come ashore,” said Raum-Suryan, who used spotting scopes as well as remote video cameras to document the entangled mammals. “And because these animals can be observed only when they are on land, the numbers might be significantly higher.”
Raum-Suryan said sea lions often sink when they die at sea, resulting in few dead and entangled Steller sea lions stranding on beaches. “This adds to the difficulty of assessing the mortality of the entangled mammals,” she said.
Of the observed identifiable neck entanglements, black rubber bands were the most common neck entangling material (62 percent), followed by plastic packing bands (36 percent) that are cut and glued at the ends around cardboard boxes to keep boxes from bursting.
“We don’t want to point fingers or place blame, because the important thing here is that entanglement is preventable and everyone can do their part,” Raum-Suryan said. “From fishers and crabbers to beachcombers, people can help get the word out on what I call ‘Lose the Loop,’ or making sure all loops – from six-pack plastics to packing bands – are cut before any bands are discarded.”
Sea lions are curious animals and tend to seek out and play with entangling debris, which is how loops lodge around their necks and then cut into the flesh as the animals grow.
Raum-Suryan, who participated in a similar study in southeast Alaska where salmon fishing gear was a more common cause of entanglement, is working with Oregon’s fishing and crabbing industry to raise awareness about the bands and loops.
She has also suggested to manufacturers and packaging companies that the glue used to attach packing bands around boxes could be biodegradable so it would release after short exposure to saltwater and sunlight. Other materials also could be manufactured to biodegrade more quickly.
In both fishing and packaging industries, plastics and synthetic materials have replaced natural fibers over the past 50 years because these materials are lower cost, lighter weight, stronger, and more durable. But they last longer once discarded or lost, are less likely to sink, and are more difficult for marine organisms to escape from once entangled.
“Because entanglement is preventable, even one animal dying this way is too many,” Raum-Suryan said. “These are human-caused problems, and we can prevent them by being aware and making a few changes, like cutting all bands at home and at work.” She has seen packing bands used on boxes ranging from toys to furniture.
Raum-Suryan worked with Alaska Fish and Game to produce an educational video that helps viewers understand entanglement and what they can do prevent it. The video is available on a free DVD from the Alaska Fish and Game, or can be viewed online at: http://www.multimedia.adfg.alaska.gov:8080/WildlifeConservation/entanglement.wmv
The threatened and endangered Steller sea lions are much larger than the protected California sea lions that are common along the Oregon coast. Male Steller sea lions can weigh up to 2,500 pounds, compared to only 700 pounds for a male California sea lion The vocalizations and coloring also differ. Steller sea lions are lighter in color with thick necks and roar, while California sea lions are darker and bark.