While scientists, wildlife managers and others continue to untangle the complex web of fish, boat and water quality issues that affect the health of Southern Resident orca whales, the population remains endangered — and continues to shrink.
The National Marine Fisheries Service published a five-year review of the species on Jan. 4 in which it recommended the orca's status under the federal Endangered Species Act remain unchanged. The species uses West Coast and Salish Sea habitat and eats the region's salmon.
Despite billions of dollars spent and dozens of studies authored since the Southern Resident orca was listed as endangered in 2005, there are now 15 fewer whales than there were in 2005.
The population in 2021 reached a high of 73 whales, down from 88 at the time of listing. It's also a five-whale loss since the previous review, when 78 orcas were accounted for in 2016.
With few females in the remaining population and emerging concerns such as diseases in the marine environment and the effects of inbreeding on whale health, that downward trend is expected to continue.
"There is no doubt we will continue to see that population continue to shrink," said Brad Hanson of the Northwest Fisheries Science Center, a regional office of the National Marine Fisheries Service. "That is why we are continuing to try to improve the environment for the whales on a wide variety of fronts."
While the delisting goal of documenting at least 2.3% population growth per year for 28 years remains a long way off, Hanson is hopeful that someday it could be achieved.
"If we still work to provide a viable habitat — and that's prey that's sufficient to meet the population's needs, as well as an environment that has relatively clean water and is relatively quiet — then at some point the population should grow," Hanson said.
When the species was listed as endangered, the National Marine Fisheries Service identified three main threats to the whales' survival: a shortage of fish to eat, pollution in the water and disturbance from boats.
While at least 22 studies examined those threats in 2021 alone, the scientific community is far from fully understanding those threats.
"Part of the problem is that they are all interconnected to a certain extent, and that has been challenging in trying to establish what the role of each of these might be and what the most important ones might be," Hanson said.
It's also difficult to pinpoint how efforts to restore chinook salmon habitat, increase hatchery production, restrict fisheries, regulate whale watching and other boat traffic, and reduce contamination in the marine environment are benefitting the orcas.
"While many key data gaps have been filled and protective actions are assessed on an ongoing basis, it remains challenging to link any specific action directly to population changes," the newly-published review states. "Recovery of the ecosystem, food web, and the whales is a long-term effort. It will take many years to see the benefits."
While federal, state and local efforts to study the orcas and improve conditions for them are ongoing, new challenges, such as the whales' recent change in summer habitat use, have cropped up.
"We have almost a year-round understanding of what the diet is — or has been," said Hanson, who spends part of the year studying the orcas by boat. "As soon as we thought we had started figuring everything out, the whales started using other parts of their habitat."
New study topics are emerging as well, including more probing into genetics, inbreeding and infectious diseases.
Genetic analysis, which recently involved mapping the species' entire genome, will help to pinpoint lineage and could provide insights into the health of individual whales.
"We always had a pretty good idea who mom and her offspring were, but dad was the big question," Hanson said.
Already, genetic analysis has revealed four inbred orcas in the population.
"What are the implications of being inbred? ... Is there an impact to the population?" Hanson said. "It's things like that that we are continuing to work on. There is no shortage of questions to be answered with this population."
