Weight loss among endangered orcas off West Coast sparks concern

Open this photo in gallery:

Members of an endangered population of orcas off the West Coast are losing weight and growing too slowly, scientists have found, prompting Washington State to introduce new restrictions to protect them.

The southern resident killer whales are a group of killer whales considered endangered since 2003 in Canada and 2005 in the U.S. They number 75 members, down from a peak of 97 in 1996. The decline of these animals is linked to growing marine traffic and pollution, and a diminishing abundance of the chinook salmon that they depend upon. Salish Sea chinook salmon populations are down 60 per cent since the Pacific Salmon Commission began tracking them in 1984.

Last week, Washington’s Department of Fish and Wildlife (WDFW) declared at least 13 of the 75 whales vulnerable. By using measurements from drone photographs, researchers identified several pregnancies among the southern resident killer whale population and a dozen members in poor condition between September, 2021 and April, 2022.

Researchers say new J-pod calf is a girl for southern resident orca population

The Washington researchers’ findings are similar to those recorded by researchers at the University of British Columbia (UBC) in a recent study. Tracking data on the population shows the whales have not been getting enough to eat since 2018.

Because of the findings, the WDFW issued an emergency order requiring commercial whale-watching vessels to keep at least one-half nautical mile away from the iconic coastal species this summer, and all boaters are urged to be “whale wise” and do the same.

According to the Washington researchers, 12 whales were in poor condition based on measurements of fat behind the skull, which puts them at a two-to-three times higher mortality risk. In addition, researchers identified two young whales that were exhibiting slower-than-expected growth, which is measured by length.

“These particular 12 whales are thinner now, even compared to previous times of year,” said Julie Watson, the WDFW’s killer whale policy lead.

“It’s a very endangered population and these particular whales are just especially in need of some fattening up, to put it bluntly.”

Open this photo in gallery:

Just days before the WDFW released the news, UBC researchers found the intelligent cetaceans have been in an energy deficit for six of the last 40 years – meaning the energy they get from food is less than what they expend. Three of those six years came in the most recent years, from 2018 to 2020. The average difference in energy is 28,716 calories, or about 17 per cent of the daily required energy for an average adult killer whale, the researchers say.

The scarcity of salmon may be driving the orcas’ poor health. This lack of food can affect the whales fertility, growth and potentially even their social behaviours, said study lead author Fanny Couture, a doctoral student at UBC’s Institute for the Oceans and Fisheries and the Ocean Wise Conservation Association.

“Killer whales are very social animals, but they will spend less time, for example, socializing, or teaching young calves how to hunt. So we believe that the lack of food can have a very detrimental impact at several levels for this population.”

Over recent years, the Canadian government has introduced a string of measures to support the recovery of these animals, including requiring vessels to slow down, tougher regulatory controls on contaminants and spending aimed at protecting and boosting the stock of chinook salmon. Whale-watching vessels and other boats must also maintain a minimum 400 metres distance from all whales in the southern resident orca’s critical habitat and keep 200 metres away outside that area.

Earlier this year, Ottawa announced two new seasonal slowdown areas near Swiftsure Bank, and that expanded fishery closures will be put in place for commercial and recreational salmon fisheries in a portion of Swiftsure Bank, the Southern Gulf Islands, the Strait of Juan de Fuca and the mouth of the Fraser River.

Lara Sloan, a spokesperson for Fisheries and Oceans Canada, said the department can’t comment on the effectiveness of the government’s recovery strategy, because the orcas’ low growth rate means the time frame for recovery will be more than one generation and could take 25 years.

Deborah Giles, research director for Wild Orca and a research scientist at the University of Washington, called Ottawa’s moves over the years “progressive, bold.”

Open this photo in gallery:

She said limiting fishing and interactions with humans onboard boats “are going to have very important positive impacts for these whales.”

However, Dr. Giles added that the situation for these animals that is already “incredibly imperiled” can worsen as fish stocks decline.

“We know ... this population should be having around six or more calves per year. And that’s not the case; that’s not happening. Many years we go by with no calves being born or just one.”

She criticized the U.S. government for not doing enough to support the recovery of these animals. The American government has aimed at rebuilding depleted populations of salmon, minimizing pollution, disturbance from vessels and the risks of oil spills. But Dr. Giles is calling for stricter fishing regulations. For example, she wants the federal government to focus on limiting bycatch of chinook salmon in other fisheries.

“We need to have more serious fishing restrictions and safeguards in place in order to make sure that enough fish get down and back to these waters where the whales spend their time.”

We have a weekly Western Canada newsletter written by our B.C. and Alberta bureau chiefs, providing a comprehensive package of the news you need to know about the region and its place in the issues facing Canada. Sign up today.