More gray whales are passing below the Golden Gate Bridge for a stop in San Francisco Bay this spring as they migrate along the California coast, The San Francisco Chronicle reports.
While sightings of visiting gray whales, which can reach 39 feet long and weigh 60,000 pounds, are delighting tourists, marine biologists say the surge in strays may be a sign of trouble, The Mercury News reported.
Scientists worry the whales, which are making their annual 11,000-mile trip north from Mexico to Alaska, may be heading into the bay in search of food or shelter if they are weakened by hunger before continuing their journey, The San Francisco Chronicle reported.
Experts in Washington say they’ve also spotted more gray whales than usual in Puget Sound, Salon reported.
“We also have wandering whales that aren’t in good condition and showing up in strange places,” said John Calambokidis, a research biologist at Cascadia Research, according to the publication.
Two dead gray whales were found in San Francisco Bay in early March, and one showed signs it had died of malnutrition, ABC News reported. The body exhibited a lack of blubber and body fat, and its stomach was empty, according to The Mercury News.
A San Francisco Bay stopover also can put whales in shipping lanes, “putting them in danger of vessel strikes,” said Michael Pierson, a naturalist with San Francisco Whale Tours, according to The San Francisco Chronicle. “One already has some pretty gnarly scars on its left flank.”
One possible explanation may be that the gray whale population, rebounding since they were put under environmental protections, may have grown too large, Salon reported.
“As gray whales have recovered it could be possible they are facing the limits of their food supply and are maybe more vulnerable,” Calambokidis said, according to the publication.
Since gray whales normally do most of their feeding over the summer in the Arctic, climate change also may be having an effect, The San Francisco Chronicle reported.