Thank you.
Southern residents have been separate from other killer whales since the ice age. They're genetically and culturally distinct. They share their diet with other residents, the northern residents, but they differ in diet from the transients and offshore killer whales with which they share their habitat.
They once numbered between 1,000 and 2,000 individuals, but only 74 remain, and there has only been successful reproduction in two of the last seven years.
While they range from southeast Alaska to central California, they are most often observed in the Salish Sea. There are many causes of the decline. Prey availability is one of them. Chinook are their primary prey, but they also rely heavily on chum salmon and on coho. They use bottom fish when salmon are not available.
To help with the prey problem, we need to address habitat. Repairing habitat is important to spawning and rearing juvenile salmon. The vegetation around streams and how we manage water flows in streams are important to salmon survival.
Near-shore habitats are also important to juvenile salmon, and protecting them from construction and development—docks and things like that—is also quite important.
Invasive species pose a risk. They can restructure ecosystems, reducing their productivity and reducing the food available to the whales.
Barriers to migration are another significant problem. Dams, culverts and in some cases thickets of invasive plants can block migration. They can also make salmon more vulnerable to predation as they try to navigate blockages in their migration routes.
Hatcheries are a double-edged sword for killer whales. Ideally, they would serve as lifeboats where depleted runs could be supported, and then the hatchery could be phased out once wild runs were restored. However, they have become long-term sources of fish for humans, and as a result, the focus has been on numbers rather than body size. We've seen a significant decline in the size of chinook salmon as a result of increasing reliance on hatcheries.
While eliminating harvest would help, it would be inadequate to recover the species. What we can do is move the locations where we do harvest by harvesting after the fish have passed through the whales. We would reduce competition with them, and it would also eliminate disturbances that make the few remaining fish harder to find.
Aquaculture has been identified as a source of disease that affects wild salmon. Some aquaculture facilities have used loud sounds as acoustic deterrents, and this has had a negative impact on killer whales.
Killer whales face competition from other predators such as seals and sea lions. This was not a problem in the distant past; however, human modification of the habitat and timing of runs has enabled pinnipeds to be more effective predators than they used to be. Also, the decline of transient killer whales that feed on pinnipeds has made a population boom in pinnipeds possible. While transients are catching up and will eventually put the ecosystem back in balance, it's an issue we need to pay attention to.
We also have upcoming problems. Climate change is going to be a problem. Warming is not good for salmon. The University of Washington anticipates a 40% decline in salmon populations due to warming.
Ocean acidification is another problem we can anticipate. It's likely to wipe out a link in the food chain, and that will also be a problem in the future.
Disturbances from fishing boats, whale-watching boats, shipping, marine energy production, coastal development and military exercises all make it harder for killer whales to find the limited prey that remains.
Toxins are also a problem. Some are chronic, like PCBs. We have hazardous waste sites that need to be cleaned up, we have ongoing problems with toxins in stormwater and wastewater, and we have concerns with agricultural runoff as well. Transportation is the major source of toxins in stormwater.
We also have to worry about acute toxins. Oil spills pose a major threat. We may have lost a few killer whales from the grounding of the New Carissa in Oregon several years ago. We're also all familiar with the Exxon Valdez spill that killed at least 13 killer whales in Prince William Sound and may have been responsible for the deaths of over 30. As we ship other chemicals by sea, we run the risk of spilling those and causing problems as well.
Disease is another problem we need to worry about. The small population that's been in a bottleneck for generations faces loss of resistance to disease with the loss of genetic diversity.
We also need to be concerned about emerging diseases. For example, we had a porpoise die-off in the Salish Sea that was traced to eucalyptus trees introduced from Australia. We also lost quite a few killer whales at the same time, but none of the bodies were recovered. We don't know whether there's actually a link there.
Another concern is a lack of barrier between the human and marine environment. We know that the bacteria in fungi growing in killer whales have developed antibiotic resistance. We found a dozen species of potential pathogens resistant to a total of about a dozen different antibiotics. This lack of barrier between humans or pets and agricultural animals is a concern for the spread of disease from inshore populations to the whales.
Another thing we need to be aware of is incidental takes. It's been a minor problem for killer whales in the past. If someone proposes to introduce a new fishing technology, we need to be careful it will not result in killer whale mortality.
Finally, I'd like to comment on critical habitat.
At present, the whole range of the southern resident killer whale population is inadequate to support the viable population in its current condition. Therefore, the entire range should really be considered critical habitat. We can identify core areas that are more important than others, but a strategy of maintaining ecological function and the quality of critical habitat throughout the range is important. Enhancing the habitat's quality in core areas would be the other step to take.
Thank you.