Transient Killer Whale
Killer Whale (Orcinus orca)
Overview
Three distinct types of killer whales, often called orcas because of their Latin name, Orcinus orca, can be found in the Salish Sea.
People are most familiar with the fish eating ecotype or “resident” orcas. These whales are salmon eaters, preferring Chinook as shown in recent studies.
In the Salish Sea there are two resident groups, the Southern Resident community (made up of 3 pods; J, K, and L) and the Northern Resident Community (made up of 16 pods; A1, A4, A5, B1, C1, D1, H1, I1, I2, I11, I18, I31, G1, G12, R1 and W1).
Less commonly seen are the marine mammal eating ecotype or “transient” killer whales. While the fish eating residents hunt in large groups, the mammal-eating type of killer whales are usually seen in small groups of 3-5 animals.
Occasionally, “offshore” ecotype killer whales are spotted in the Salish Sea. These slightly smaller animals are thought to be fish eaters like the residents.
Orcas can be identified by the shape of their dorsal fin and white saddle patch and are individually known by name to experienced whale watchers.
Status
All ecotypes of killer whales are listed as Endangered in Washington State.
The US Federal Government lists the Southern Residents as endangered and the Canadian Federal government lists Offshore killer whales as a species of concern, the Northern Resident and Transient populations as threatened and the Southern residents as Endangered.
Toxins and Disease
Killer whales from the Salish Sea are some of the most contaminated marine mammals in the world and toxin loads are considered a factor in causing the decline of the southern resident population. Disease too is a major threat to the long term health of killer whale populations.
Oil Spills
Oil spills have been called one of the greatest threats to the long term survival of the southern resident killer whales.
To address this concern, the SeaDoc Society gathered a group of almost 40 scientists to develop a plan for keeping killer whales out of an oil spill.
To see notes from that meeting see: (attached)
To read about how the Exxon Valdez is thought to have impacted resident and transient killer whales in Alaska, see (attached)
More Information
Below this line are all the content items in the SeaDoc site that have been tagged with the term Killer Whale.
The Mystery of Surplus Predation
In the Salish Sea, some transient killer whales seem to be killing sea lions for no particular reason. Joe Gaydos provided background for a Kitsap Sun piece by Christopher Dunagan discussing the four sea lions apparently killed by blunt trauma from orcas in a single month.
A 2005 publication by Gaydos discussed five harbor seal pups found decapitated by killer whales, but not eaten.
The article discusses possible causes of this "surplus predation" and reinforces the importance of quick reporting of stranded and dead marine mammals, because the faster the animals can be recovered, the more we can learn from them.
Kitsap Sun: http://pugetsoundblogs.com/waterways/2010/05/14/transient-orcas-may-be-l...
Photo: Stranding Network volunteer Maria Webster standing by one of the dead Steller sea lions on North Beach of Orcas just before SeaDoc necropsied it. Credit: Joe Gaydos.
Gray-colored transient killer whale spotted
