SAN FRANCISCO— The Center for Biological Diversity filed a legal petition with the Biden administration today requesting mandatory speed limits for vessels off California to protect whales. Vessel strikes are one of the leading causes of death for blue, fin and humpback whales off California’s coast.

The petition to the National Marine Fisheries Service asks that the current 10-knot voluntary speed limits through whale habitat be made mandatory. It follows a federal lawsuit the Center and allies filed in January challenging the Fisheries Service and U.S. Coast Guard for failing to meet an Endangered Species Act requirement to consult on ways to reduce the number of whales struck by vessels along California’s coast.

“Too many whales die from ship strikes off California, and the solution is mandatory speed limits,” said Catherine Kilduff, an attorney at the Center. “We know that slowing vessels down gives whales a fighting chance to avoid getting hit. And we know voluntary speed limits just aren’t working. Speed limits make our freeways safer, and they’ll make our shipping lanes safer too.”

Five dead whales have washed ashore in the San Francisco Bay Area since March 31, with at least three — including an endangered juvenile fin whale — confirmed or suspected to have been killed by vessel strikes. Another dead fin whale was draped across the bow of a container ship as it entered San Francisco Bay in 2018.

Federal records document at least 26 whales killed by vessel strikes along the West Coast from 2014 through 2018. That makes vessel strikes one of the leading human-induced causes of death of large whales.

Recent studies have found vessel strikes are even more lethal than previously understood. Scientists say the actual number of vessel-strike deaths could be 20 times larger than documented since most dead whales sink.

The petition calls for a 10-knot mandatory speed limit in both the Southern California and San Francisco Bay Area regions for vessels 40 feet or longer. A historical analysis of ship strikes involving large whales found none were seriously injured or killed by ships moving slower than 10 knots.

Commercial vessels would also be encouraged to travel at least 24 nautical miles offshore when traveling between those regions. Finally, the petition asks for vessel traffic thresholds, which would trigger additional mitigation measures when the risk to whales increases.

The Center successfully secured this month’s final federal rule designating 116,098 square nautical miles of the Pacific Ocean as critical habitat for endangered humpback whales and won new rules protecting whales from being entangled in fishing gear off California’s coast.

The Center and its allies also contested plans to increase oil-tanker traffic into San Francisco Bay that could harm whales. The group has long called for vessel speed limits and other maritime rules to better protect imperiled marine life.