Since banning the use of gill nets from the shallow coastal waters along the coast of California, United States, in 1994, the population of harbor porpoises, one of the smallest marine mammals, have steadily rebound.
“Nowhere in the world has a harbor porpoise population ever been documented to rebound from past gill-net impacts,” says Karin Forney, a research biologist at the National Oceanic and Atmospheric Administration, who has been monitoring harbor porpoise in California for more than 30 years. “Harbor porpoises show that if you stop killing them, thank you, they can return. That they’re capable of recovering. They have a resilience and they will rebound if we just let them.”
Harbor porpoises, one of the smallest toothed whales, live only in shallow waters where gill nets used to be set. They are among the most vulnerable species to this type of fishing net, along with the Indo-Pacific finless porpoise in Asia and the endangered vaquita in the Gulf of California. The decline in Central California seabirds alerted scientists about the dangers of gill nets in shallow waters for many species, including harbor porpoises and sea otters. Now, along the West Coast where gill nets have been removed, populations of harbor porpoises have gone up.