Why aren’t whales better at avoiding ship strikes? The problem extends beyond the Bay Area (which is featured in the video above); according to a new publication, “For some endangered whale populations, ship strikes are a major threat to survival and recovery.” The study’s senior author, Jeremy Goldbogen of Stanford’s Hopkins Marine Station, explains the whales’ predicament, “It’s not part of their evolutionary history to have cargo ships killing them, so they haven’t developed behavioral responses to this threat. They simply have no compelling response to avoiding these dangerous ships.”
Goldbogen and his colleagues explored whales’ reactions to ships near the busy Ports of Los Angeles and Long Beach in southern California. Blue whales congregate in this area to feed on the abundant krill, and the ports see an average of 18 ships moving in and out each day.
In a period of 24 hours, they found 20 ships that encountered nine whales at distances ranging from 60 meters (200 feet) to 3.6 kilometers (2.2 miles). The team found that the whales don’t appear to avoid areas with heavy ship traffic or to move directly away from ships. But the team discovered one reaction: the whales performed a “response dive” more than 50 percent of the time when they came in close contact with a ship. Essentially, the cetaceans played dead. Never did they simply swim the other way.
“Blue whales have a subtle and not very convincing ability to get out of the way of oncoming ships,” says Goldbogen. “Instead of diving, where the animal kicks tail up and goes down vertically, they just sink horizontally. This results in a slow dive and leaves them susceptible to ship strikes.”
The scientists believe that perhaps slowing ships down to match the slow dives of whales may reduce ship strikes in the future. With that in mind, they plan to conduct a second round of tests to monitor the movement of both blue and humpback whales; their follow-up study aims to provide more data to influence ship speed.