Ship strikes are killing many gray whales and blue whales in or near San Francisco. Four of the ten gray whales that died this year were struck by ships. Ship strikes are a worldwide concern for blue, humpback and fin whales which are more likely to be struck and die as a result of being hit by ships. The largest animal to ever live, the blue whale, with an estimated population of 8,000-9,000 individuals is particularly vulnerable.  

The tonnage of ships has increased over the last few decades. Whales that frequent shipping lanes adjacent to San Francisco Bay ports are at risk. That is because record numbers of humpback and blue whales have been feeding in recent years off the coast and even in San Francisco Bay.

During the gray whales' winter migration which usually ends in May, the whales normally do not enter the Bay or linger in the area. They have been stopping midway through their migration to Alaska to get enough food to allow them to travel the remaining distance.The population has grown in the last decade and is estimated at 27,000 which is the highest since surveys began in 1967. Some marine biologists question whether their numbers have reached the limit of what their environment can sustain. It is also suggested that the loss of Arctic sea ice due to local warming is to blame. Tired and malnourished whales are more likely to be struck by ships, attacked by orcas, or entangled in fishing gear.

In a typical year, only one or two gray whales are washed ashore in the Bay Area. While their numbers have been increasing, the fact that some whales are malnourished is a concern and could have devastating effects on the entire West Coast whale populations. Lack of food is already killing many of the resident orcas of J, K and L pods of Washington.

With international shipping companies agreeing to reduce speeds voluntarily, federal officials say their campaign to slow ships is gaining strength. Their reduced speed going in and out of California ports is less likely to injure or kill whales. 

Shipping firms, representing 45 percent of the 8,000 inbound vessels that pass through the area, cut their speed in 2018 to 10 knots (11.5 mph) or less to areas populated by whales. These include the Farallones, Channel Islands, Monterey Bay and Cordell Bank marine sanctuaries. Often, whales have to travel through national marine sanctuaries to get to their destination.