Harbor Porpoises have rebounded in the San Francisco Bay.
30 years ago, you never would’ve seen so many harbor porpoises in the Bay. During World War II, an anti-submarine net was set up there, cutting the porpoises off from their usual feeding spot.
Although the net was eventually removed, the harbor porpoise population continued to decline due to gillnetting by local fisheries. Scientists with NOAA Fisheries’ Southwest Fisheries Science Center estimated in a Marine Mammal Science study that up to 300 porpoises per year may have been killed in California’s set-gillnet fisheries in the 1980s.
It wasn’t until the late 1980s that gillnetting was finally banned. This, combined with improved water quality, ultimately saved the Harbor Porpoise population.
“We didn’t really know how heavily the Morro Bay population had been impacted by the white seabass and halibut gillnets at the time,” said NOAA research biologist Karin Forney. “It is now clear that the toll was more severe than we thought.”
Beginning in about 2009, harbor porpoises started appearing by the hundreds in the San Francisco Bay. Their population is now estimated at 7,777 individuals.
Other porpoise populations in Morro Bay, Monterey Bay, and Northern California/Southern Oregon have also seen rebounds in their numbers.
[Featured Image: Instagram / @whalegirlorg]