Of Plastics and Whales
A dead gray whale washed ashore on West Seattle’s Arroyo Beach last week. In itself, that is not an inherently unusual occurrence: five to ten gray whales die annually in Puget Sound waters, unable to complete the lengthy migration from the lagoons of Baja California, where they breed, to their summer feeding waters north of Alaska. Indeed, that whale was the fourth discovered in the region in a little over a week.
What was especially interesting about this particular whale, however, was its stomach contents. According to a postmortem examination by Cascadia Research:
The animal had more than 50 gal Air Max Air Max >lons of largely undigested stomach Air Max contents consisting mostly of algae but also a surprising amount of human debris including more than 20 plastic bags, small towels, surgical gloves, sweat pants, plastic pieces, duct tape, and a golf ball.
(If you’re looking for a good gross out, this slideshow contains images of those stomach contents).
However, the trash was likely not to blame for the whale’s death, despite its extent:
The debris, while numerous, made up only 1 2% of the stomach contents and there was no clear indication it had caused the death of the animal. It did clearly indicate that the whale had been attempting to feed in industrial waters and therefore exposed to debris and contaminants present on the bottom in these areas. Gray whales are filter feeders that typically feed on the bottom and suck in sediment in shallow waters and filter the contents to strain out the small organisms that live there. They have been known to accumulate material including rocks and other debris from the bottom ingested in this process. While debris has been found in the stomachs of some previous gray whales found dead in Puget Sound, this appeared to be a larger quantity than had ever been found previously.
Unfortunately, there is little reason to believe that gray whales will be any less likely to ingest such pollutants in future.
A in the journal Marine Pollution Bulletin found the average density of marine debris along seafloor habitats off the California coast to be “significantly higher” than the 1990s. They wrote:
The legacy of such gear can be devastating to marine populations in Puget Sound; divers reported a single derelict gillnet suspended between rocks off the southwest Air Max corner of Lopez Island in the San Juan Islands that had thousands of bones piled 1 3 feet deep and running the length of the 30 m span of the net.