President Barack Obama, first lady Michelle Obama, and their daughter Sasha watch a porpoise as they take a boat ride in St. Andrews Bay in Panama City Beach, Fla, Sunday, Aug. 15, 2010. The Obamas are spending the weekend in Florida. (AP Photo/Susan Walsh)
After being kicked out of the San Francisco Bay decades ago, some determined porpoises have returned to frolic in the waves.
Once plentiful, porpoises vanished from the Bay in the 1940s. The likeliest culprit is bay activity related to World War II, including underwater mines and a net to stop submarines beneath the Golden Gate Bridge.
After the war, an environmentally damaging fishing process called "gilnetting" kept porpoises away. Gillnets surround large areas and trap animals above a certain size by ensnaring their gills.
Now that the bay is cleaner, less crowded, and fished more sustainably, a group of over a hundred of porpoises has finally returned. They've found plentiful food and a more supportive environment. The limited boat traffic in the bay seems not to bother them.
This could be a good sign for the environmental quality of the bay. A variety of other species, such as sea otters, have suffered population declines in recent years.
Researchers are hoping to tag the animals so that they can be tracked over the coming years.
If you're looking to catch a glimpse, hang out near Horseshoe Cove at Fort Baker, or Cavallo Point.