“The impacts of letting these two species disappear would be felt for generations,” wrote Jay Inslee recently. The Washington State Governor was expressing his grave concern at the dwindling numbers of black-and-white killer whales or orcas and their primary prey, the king salmon, off the Pacific Northwest coast of the US. And while the whales have been listed as an endangered species since 2005, and despite Inslee issuing an executive order directing state agencies to do more to protect them, halting their decline has thus far eluded the local authorities, and experts are struggling to pinpoint the cause.
In his article this week for The New York Times, Jim Robbins explains that normally four or five calves would be born each year among this whale population, but that this year, not one has been born and the number has dwindled to just 75, which is a 30-year-low. And while much is still unknown about the plight of these orcas, biologists and conservationists believe that there may be several significant and interconnected factors at play.
As Robbins writes, the biggest contributing factor may be the disappearance of the Chinook or king salmon. Orcas can consume 30 of these fish a day, which measure more than 40 inches long, and hunting sufficient numbers of smaller prey would require much more energy.
Researchers have also expressed their concern that reproducing females are aging out of the population and are simply not being replaced; some conservationists believe that the orcas’ decline is yet another sign of a marine ecosystem in collapse; and in recent years there has been a focus on the effect of anthroponeses, or diseases that humans may be passing on to wildlife.
The underwater world in the region is also getting noisier, especially in Haro Strait, which is between the San Juan Islands and Vancouver Island, and one of the orcas’ favorite summer hunting grounds. Increasing sound levels make it harder for the whales to locate their prey, and to communicate prey location among themselves, as well as cause hearing loss.
Another factor is the pollution in Puget Sound, caused by municipal and industrial waste and spillages from wastewater treatment plants, as well as the dumping of chemicals and pesticides, some of which are now banned. The pollutants accumulate in the salmon as they feed, and are subsequently ingested by the whales. Indeed, killer whales carry some of the highest levels of pollution of any marine animal.
And as Robbins sadly notes, while much of the pollution emanates from the region’s industrial past, Boeing disclosed earlier this year that it had discharged highly toxic PCBs into the Duwamish River, which flows into Puget Sound, thousands of times over the legal limit over the past five years. Such toxins suppress the whales’ immune systems, making them more susceptible to disease and often impeding reproduction.
The orcas are also facing a new threat, following the agreement to expand the Trans Mountain Pipeline. This would, according to certain estimates, multiply oil tanker traffic through the orcas’ habitat by seven times and expose them to excessive noise and the effects of potential spillages. Construction is set to begin in August, in the face of opposition from Governor Inslee and many environmentalists.
Despite citing this raft of possible causes, experts really aren’t sure what it is that is actually raising the whales’ mortality rate. Steps are being taken to try and halt the population’s decline, such as the rearing of king salmon as food in hatcheries, but as The New York Times’ article makes clear, this is far from a certain fix and in the end, trying to maintain a population of whales in the shadow of one of the fastest growing cities in the US may simply not be possible.
“It’s an ecosystem-wide problem,” said Brad Hanson, team leader for research at the Northwest Fisheries Science Center. “Things are out of whack and we have to get them back to where we can sustain killer whales. And the clock is ticking.”