Boat speed is a big problem for Puget Sound’s endangered killer whales, according to new research published Wednesday.
The number of whale-watching vessels in Washington and British Columbia has more than quadrupled since the 1980s. At times, killer whales, or orcas, will be tailed by more than 20 boats when they enter Puget Sound and the Salish Sea.
“Of all the characteristics that we examined, vessel speed was the most important factor for how loud it was for the whales,” said Juliana Houghton, lead author of the paper, which was just published in the journal PLOS One.
Houghton analyzed hydrophone recordings from suction tags that were attached to more than 20 orcas over the past several years. She took the volume levels in the recordings and lined them up with the numbers of boats that were nearby at the time. She also recorded the size of the boats, how many propellers they had, and the speed they were traveling.
Vessel traffic and noise are one of the main threats to Puget Sound’s resident killer whales, which now number about 80 animals. Previous studies have shown that southern resident killer whales raise the volume of their calls and change their behavior when vessels are present. The whales call and echolocate to communicate with one another and find food.
Watch: Video of the orca tagging operation
Currently, federal regulations require that boats stay 200 yards away from orcas, but boaters aren’t subject to any specific speed limits when whales are nearby.
The National Oceanic and Atmospheric Administration, which funded the research in partnership with the University of Washington, said the new research will be taken into consideration when the administration weighs the possibility of new regulations on speed limits for boats near orcas.
The hydrophone recordings for the study were gathered from 2010 to 2012. EarthFix featured the orca tagging operation in 2012. Click here for Ashley Ahearn’s account of the trip.