Shipping lanes that carry about 20 cargo and cruise vessels a day in and out of San Francisco Bay are being revised in an effort to reduce fatal collisions with whales, federal officials said Thursday.
The proposal developed by the U.S. Coast Guard and the National Oceanic and Atmospheric Administration modifies shipping lanes that head north, west and south from the Bay, limiting their overlap with areas frequented by endangered blue, humpback and fin whales.
Five whales were killed by confirmed or likely ship strikes in the San Francisco area in 2010, and scientists say the mortality rate may be much higher because most dead whales sink.
The northern shipping lane, which runs along the Marin County coast, will be narrowed to 3 nautical miles wide and extended by nearly 17 miles, sweeping past the Point Reyes Peninsula.
It will also be turned slightly to keep ships away from Cordell Bank, known as a "destination feeding ground" for blue and humpback whales, giant mammals that eat krill, a small crustacean.
Narrowing the western lane is intended to shift vessel traffic away from the seabird colony at the Farallon Islands.
"This is a very positive step," said Lance Morgan of Glen Ellen, president and CEO of the Marine Conservation Institute, a nonprofit organization.
Morgan served as co-chairman of a working group that included environmentalists, whale experts and shipping industry representatives that assessed vessel strikes on whales and recommended, in a June report, modification of shipping lanes.
The idea, Morgan said, is to "reduce the probability" of whale vs. ship collisions.
Shipping lanes handle vessels over 300 gross tons, including tankers, container and cruise ships.