Post-Unusual Mortality Event Monitoring Begins in Washington State with the Examination of 2 Dead Gray Whales and an Entangled Gray Whale Response

With the official closure of the 2019-2023 Gray Whale Unusual Mortality Event (UME) comes a new phase: post-UME monitoring of gray whale mortalities. Within the last week, Cascadia Research and collaborating organizations began this monitoring with examinations of the first two gray whale strandings of 2024 in Washington waters. A team led by Cascadia also responded to an entangled whale in Grays Harbor on 17 April.

The first stranded whale washed ashore near Ocean City on the evening of April 10. This adult male was just under 42 feet long and was moderately decomposed. A necropsy was conducted by biologists and volunteers with Cascadia Research, Washington Department of Fish and Wildlife, and the Quinault Tribe. Preliminary results indicate that this whale was malnourished, and there were no signs of traumatic injury or disease.

On the evening of April 12, another adult male (39 feet) was reported dead on Vashon Island. World Vets, the responding organization for this area, coordinated the response, and the animal was necropsied by Cascadia Research and Washington Department of Fish and Wildlife. This whale was matched to an individual in poor condition that had been recently sighted in a variety of locations in southern Puget Sound, including Olympia, Des Moines, and Bremerton and was being monitored by Cascadia Research and Orca Network. It was last sighted alive near Redondo on April 10. This whale was severely emaciated, and findings from this necropsy were consistent with malnutrition as the primary cause of mortality. Samples from both whales will be analyzed for further information on cause of death and will contribute to additional ongoing research projects.

The entangled gray whale was reported to NMFS on 16 April in Grays Harbor. A team from Cascadia and SR3 responded on 17 April and were able to locate and document the entanglement both from the surface and with underwater cameras while the whale was anchored inside Grays Harbor. A response team was assembled to try to free the whale at slack current that afternoon. Unfortunately, the team was unable to relocate the whale in the afternoon. A later report indicated the whale was still entangled but no longer anchored and had shifted farther west of where the team was searching. The team will be awaiting further sightings of the whale.

Gray whale mortalities have declined since the peak in 2019, and we are hopeful that we will return to baseline levels this year. Gray whale strandings in Washington typically occur between April and June, when the majority of the gray whale population passes by as they migrate to feeding grounds in the Bering Sea.

To report marine mammal strandings anywhere on the US West Coast, please call the West Coast Stranding Hotline at 1-866-767-6114 to be connected to your local response organization. Please report live entangled whales to 1-87-SOS-WHALE.