NOAA’s Greater Farallones National Marine Sanctuary advises boaters along the north-central California coast, especially in the San Francisco and Tomales bay areas, to steer clear of whales migrating through the coastal waters of the area or entering bays and estuaries. Gray whales are at a particularly high risk of collisions with vessels, since they migrate near shore. In the past few years, humpback whales have begun feeding inside the bay and in dangerously near-shore outer coast waters, which brings heightened risk of injury or harassment by boaters.
Because of this, boaters and water recreationists should use extra caution and maintain 300 feet of separation (the length of a football field) between themselves and whales year-round. From March through May, most of the estimated 20,580 gray whales make a 12,000 mile round-trip migration between Arctic feeding grounds and Mexican breeding grounds. Gray whales, including mothers with newborn calves, swim closest to shore in spring. They may pause in the surf zone, kelp beds and small bays for their calves to rest and nurse, and to avoid killer whales.
Boaters should watch for the gray whale’s blow – its exhalation – which looks like a puff of smoke about 10 to 15 feet high, since very little of the whale is visible at the surface. A whale may surface and blow several times before a prolonged dive, typically lasting three to six minutes.
In addition to maintaining 300 feet of separation, boaters should avoid cutting across a whale’s path; making sudden speed or directional changes; and getting between a whale cow and her calf. A calf separated from its mother may be doomed to starvation.
Each year, thousands of ships and smaller vessels pass through the Golden Gate. Even small-craft collisions with a whale can have disastrous results, for whale and vessel, and sometimes the boater. All whales are protected by the Marine Mammal Protection Act. Some local species, such as humpback and blue whales, are also protected by the Endangered Species Act.