Orcas can grow to 32 feet in length and weigh as much as 18,000 pounds. Orcas have a lifespan of 25 to 90 years, with females living longer than males do. They form family groups called ‘pods’. The typical pod often numbers between three and 25 individuals, but can reach a maximum of about 50.
There are a few different populations of killer whales that visit Puget Sound and the Strait of Juan de Fuca:
Southern Resident: These types of orcas are the most common visitors to Washington. They spend their summer around Puget Sound and the San Juan Islands (in the waters of both the U.S. and B.C.) and they may travel throughout the Sound at other times of the year as well. Their favorite prey is Chinook salmon. The Southern Residents are composed of three family groups of whales that have been named J, K, and L pods. Individual animals are identified by a number based on the pod membership and the birth order. Transient: Transient orcas prey on seals and other marine mammals, travel mainly offshore in small groups and are occasional visitors to the inland waters of the Puget Sound. Their range extends from Alaska to Central California. Northern Resident: Northern Resident orcas are fish-eaters that travel in pods and spend much of their time in B.C. but occasionally enter the Washington waters.
What is the problem?
The Southern Resident orcas were listed as endangered under the Endangered Species Act in November 2005. The listing signifies that the orcas are at risk of extinction.
Although the number of Southern Resident orcas has increased, these animals continue to face threats to their health from a number of stresses including ‘PBT’s‘ and other contaminants and declines in prey. The whales are also at risk from major oil spills and from increased noise from whale-watching boats and other vessels.
Contaminated Food Source:
Southern Resident orcas, which feed mainly on salmon returning to Puget Sound and the ‘Southern Georgia Basin‘, have three times the level of PCB’s and four times the level of flame retardants (also called PBDE’s) of the Northern Residents which feed primarily on salmon from further north in the Georgia Basin waters.
Transient orcas, which occasionally visit Puget Sound and the Georgia Basin and feed primarily on marine mammals such as harbor seals, have higher levels of both PBDE’s and PCB’s than the salmon-preferring resident orcas. Although the ‘Washington Department of Health‘ has recommended that humans limit their meals of Puget Sound Chinook, the Southern Resident orca continues to consume them as a major food source.
No consistent trend data exists for contaminant levels in orca because of the risk of stressing or harming the mammals during the sampling process. Samples are usually collected from dead, beached carcasses and feces.
What is being done?
Researchers have collected a whole bunch of information the Southern Resident population for more than 30 years. But, there are still major gaps in knowledge, such as where the animals go when they are not in Puget Sound, or how much of the orcas’ preferred food source – salmon – is needed to sustain a healthy population.