Mammals

A 2021 paper in the journal PLoS ONE describes a non-traditional approach to estimating the size of three harbor seal management stocks in the inland waters of Washington using aerial line-transect surveys and tagging data.

Each spring, about a dozen gray whales make a brief detour into the Salish Sea before heading north to their feeding grounds in the Arctic. Biologists dubbed these whales "Sounders" after first noting their presence in the 1990s, and the whales have become rare but widely anticipated visitors to local waters. The whales were spotted again this year, but biologists have documented a 24 percent decline in gray whale populations along the West Coast.

An article published in the Journal of Wildlife Diseases in 2021 describes trends in birth defects among harbor seals in the Salish Sea from 2003 to 2019. The results suggest a level of congenital disease in this harbor seal population that is important for continued monitoring.

An article published in the Journal of Wildlife Diseases in 2021 describes research documenting injuries among harbor seals in the Salish Sea caused by boat propeller strikes. The number of strikes increased significantly between 2002 and 2019, as did vessel traffic.

A 2021 paper in the journal PLoS ONE provides a clearer picture of what endangered southern resident orcas eat throughout the year. Chinook salmon make up the bulk of the whales' diet, but the paper suggests that other salmon species and non-salmonid fishes can also play important roles depending on the season.

Collisions with boats and other interactions with humans are "significant" causes of death for killer whales in the northeastern Pacific, a recent study says. The findings come from one of the most comprehensive looks at killer whale pathology to date, but scientists say determining how a killer whale may have died is often notoriously difficult.