National Geographic News reports:
A 2014 study found that ingestion of debris has been documented in 56 percent of cetacean species, with rates of ingestion as high as 31 percent in some populations.
“The whales that wash up on the beach are only a small percentage of those that die,” says Frances Gulland, a senior scientist with the Marine Mammal Center in Sausalito, California.
Sperm whales are particularly susceptible to plastic debris ingestion, she explains; they mistake debris for squid, their main prey. “Every sperm whale that I have necropsied has had a lot of nets and pieces of plastic” in its stomach, she says.
Gulland encountered her most extreme case in 2008—two male sperm whales stranded along the northern California coast, their stomachs full of pieces of fishing net, rope, and other plastic trash. One animal had a ruptured stomach. The other was emaciated, suggesting that it had been unable to eat. In both cases, the debris proved fatal.
The variety and age of some of the plastic suggested it had accumulated over many years. According to Gulland, who performed the necropsy, one of the whales had at least 400 pounds of debris in its stomach.
“They slowly died of starvation,” she says. “It was the first time that I had seen a large whale die from eating garbage debris.”
NOAA Fisheries Southeast marine mammal stranding coordinator Blair Mase says the number of whales and dolphins impacted by floating marine debris seems to be on the rise. Though the statistical accounting can be tricky, Mase counts at least 35 strandings of bottlenose dolphins in her region between 2002 and 2013 due to marine debris.
But surface debris is not the only culprit. Gray whales feed on the ocean bottom and inadvertently suction up marine debris along with small organisms like amphipods. In 2010, John Calambokidis, a research biologist with Cascadia Research in Olympia, Washington, assisted in the examination of a dead gray whale that had stranded near Seattle.
The debris found in the 37-foot male included more than 20 plastic bags, small towels, surgical gloves, a pair of sweatpants, duct tape, and a golf ball.
“It was,” Calambokidis says, “a dramatic representation of the degree to which we impact the marine environment.”
Editor’s Note: Neptune 911 has highlighted the bold faced sentences in this report.