January 13, 2021 — The following was released by NOAA Fisheries:
Boat traffic within 400 yards of endangered Southern Resident killer whales interrupts their foraging, often leading female whales to cease feeding altogether. That is a key finding from a new analysis of data from suction-cup tags that track the whales’ movement underwater.
Previous research observed surface behavior of the killer whales in response to vessels, while the tags allow researchers to discern their behavior during extended dives underwater. This data shows that nearby vessel traffic inhibits their underwater foraging as much or more than what scientists previously documented at the surface. These new results were published in Frontiers in Marine Science.
“We found a bigger effect in females, and that effect was more often that they gave up foraging if vessels encroached on them,” said research scientist Marla Holt at NOAA Fisheries’ Northwest Fisheries Science Center. The analysis examined whale behavior over 3 years. It included years before and after the 2011 enactment of federal regulations limiting how close vessels can approach killer whales in Washington’s inland waters.
The outsize effect of vessel traffic on female whales “could have cascading effects on the ability to meet energetic requirements to support reproductive efforts,” the scientists reported. “This is particularly concerning in an endangered population that is in decline.”