Southern Resident Killer Whale Research in the Pacific Northwest

Research to support the conservation and recovery of endangered Southern Resident killer whales in the Pacific Northwest.

West Coast

Killer Whales on the U.S. West Coast

Killer whales (Orcinus orca) are toothed whales related to pilot whales. They occur in all the worlds' oceans.

There are three main types of killer whales in the North Pacific:

Transients (marine mammal eaters)
Offshores (shark and other fish specialists)
Residents (salmon specialists).

Each ecotype differs in appearance, diet, habitat, genetics, and behavior.

Several resident communities occur in the coastal waters of the U.S. west coast to Alaska. The southernmost group of these whales is called the Southern Resident killer whales. They range from central California to southeast Alaska. However, the core portion of their range centers on the coastal waters of southern Vancouver Island and Washington State and the inland waters of the Salish Sea.

While most other killer whale populations are doing well, the Southern Residents are among the world's most endangered marine mammals. Only 72 individuals remain as of 2020.

Research Program

In response to the proposed listing of Southern Resident killer whales under the Endangered Species Act, the Northwest Fisheries Science Center established a dedicated research program in 2003.

The program aims to fill data gaps and assess the impact of potential threats to this population. We use various monitoring and survey techniques to study these whales.

Today, we know much more about the Southern Residents now than we did only a few years ago. What we learn helps inform conservation and recovery efforts at the state, national, and international levels.

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Understanding Threats

Our research focuses on four main threats to the Southern Resident population:

Prey availability, accessibility, and quality

A lack of adequate prey is one threat to the Southern Residents’ survival. A lack of prey is a function of both what the whales eat and where their prey occurs. However, prey occurrence is more than just assessing the total abundance of the fish they eat in the ocean. The whales, and their prey, range widely over a year. We study the seasonal distribution of the whales, and their prey, to understand the potential impacts of limited prey on this population.

Noise and disturbance

Underwater ship noise can disrupt the whales' use of echolocation to detect, track, and capture prey. That could limit their foraging opportunities and force them to expend extra energy to locate prey. Shipping traffic through the Salish Sea, the heart of the whales' range, has increased in recent years and is projected to grow further. We study the impacts of vessel presence and noise using on-the-water observation and underwater acoustic technology.

Dive deeper into our noise and disturbance research

Pollution and contaminants

The environment can impact the health of Southern Residents, just as it can affect our own. However, unlike us, wild animals do not sit still for routine check-ups with a doctor. We use innovative techniques to assess contaminants, disease, body condition, and other factors potentially impacting the whales' ability to produce offspring (fecundity) and survive.

Dive deeper into our health assessment research

Demographics

Many wild species maintain diversity through mixing that occurs when maturing animals strike out on their own, often joining or forming new family groups. Southern Residents do not follow that strategy. Whales stay with their mothers and their families throughout their lives. The limited number of breeding whales reduces the effective size of the Southern Resident population, leaving it less resilient to change and possibly compromising the survival of individual animals. We study the impact of small population size and inbreeding on the recovery of the Southern Residents.

We also have teams of scientists studying other parts of the ecosystem that may affect the whales. These scientists look at everything from the changing ocean conditions to salmon recovery to habitat protection and restoration.

Dive deeper into genetics and inbreeding