The three pods of whales that make up the southern resident population are an icon of the Seattle/Vancouver Island area and a popular tourist attraction around the San Juan and Gulf Islands. Their numbers dropped by 20 percent between 1996 and 2001.
They were declared endangered under Canada’s Species at Risk Act in 2004 and under the U.S. Endangered Species Act in 2005. The U.S. government acted four years after conservation groups filed suit seeking protection of the whales.
Eighty-three whales are now in the southern population, down from 99 in 1996, while the northern population, which lives largely in the Straight of Georgia, has more than 200. Seven of the southern whales, including some breeding females, died last year.
The cause of their decline is unknown, but U.S. federal biologists with the National Oceanic and Atmospheric Administration say reduced salmon supplies, pollutants and disturbance from ships and recreational boats are possible causes.
Ross said each one of those factors is "significant enough to reduce the population." Chinook populations have declined. Also, PCBs are known to suppress immune systems of marine mammals.
The amount of PCBs found in the southern killer whales is higher than the levels that damage immune systems in seals and probably contributed to a massive die-off of European harbor seals killed by a virus epidemic in the late 1980s. Seals, however, may be more prone to mass mortalities than killer whales because they collect on rocks in large groups.
Deaths of the southern whales cannot be blamed on a specific chemical or pathogen but it is likely that immune suppression plays a role, Ross said. Some of the whales have died from infections. In many cases, they die at sea and their carcasses are never found.
The northern killer whale population—which the Canadian government has designated as a threatened species—also is contaminated with PCBs that exceed the amount known to harm immune systems.
PCBs were banned in the late 1970s but they persist in ocean and river sediments. A projection by Canadian scientists shows concentrations won't fall below the amount that suppresses immune systems until 2063 for the southern residents and 2030 for the northern ones.
NOAA's recovery plan for the species, released last year, includes cleaning up old pollution and reducing new pollutants, enhancing salmon populations and evaluating whether to regulate vessel traffic in the region.
In October, Canada's Department of Fisheries and Oceans was sued by six environmental groups for deciding not to protect the whales' critical habitat.
This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.
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11 Comments
Add CommentSo - when the label says "Wild BC Salmon", that means Beware?
Reply | Report Abuse | Link to thisHahaha, yes, blame salmon. I hear they're the big polluters on earth.
Reply | Report Abuse | Link to thisIt is one of my pet peeves that orcas (Orcinus Orca of the family Delphindae or dolphin) are referred to as killer whales. It is NOT a whale.Especially in a magazine that purports to be a scientific. Please have your editors note this for future articles.
Reply | Report Abuse | Link to thisKiller Dolphin?
Reply | Report Abuse | Link to thisFat chance.
A koala is not a bear, nor is a prairie dog a canine. I doubt that "whale" is a definitive scientific term.
Reply | Report Abuse | Link to thisWhales are members of the order Cetacea. The family Delphinidae is a subdivision of Cetacea. The genus {i}Orcinus{/i} is a subdivision of Delphinidae. {i}Orcinus orca{/i}, Orca or Killer is a (the) member of the Orcinus.
Reply | Report Abuse | Link to thisIn other words, all Killer Whales are dolphins, and all dolphins are whales. Orca was introduced as a common name because Killer Whale sounded evil, not because Killer Whales aren't whales.
Stop eating salmon - farm raised or wild. Come to BC and take a look at the Fraser River and all the main streams - Pitt River, Coquitlam River...are all polluted. The farm raised salmon are even worst, since they want to control sea lice, they feed them chemical that cost other sea creatures organ deformed. Google "salmon fish farm sea lice" and the sea lice is killing the wild salmon population. All these are "The Tragedy of the Commons" lay out by Prof. Garrett Hardin decades ago. Solution - Reduce Human Population.
Reply | Report Abuse | Link to thisCetacea is the _Order_ of dolphins and whales. Much the same as Carnivora is the order of dogs, cats, and badgers. Therefore, refering to Orcas as killer whales is similar to referring to badgers as killer dogs.
Reply | Report Abuse | Link to thisThe original term (in english) for orca is blackfish. I believe, (can't find a reference) that Linnaeus himself labled orcas as orcinas orca in 1758. I don't know Linnaeus' reason for the name, but it probably wasn't because "killer whale" is too scary.
Finally, my point is that a "scientific" journal should at least reference the popular name. Orca is not mentioned once. Can't wait to read the article on Killer Dogs.
Sorry, that penultimate sentence should "reference the proper popular name".
Reply | Report Abuse | Link to this@JLair: it's "Canidae" for dogs - not Carnivora. Carnivora refers to all hunting, flesh eating animals - that would include dogs, eagles and Orca.
Reply | Report Abuse | Link to thisOrcus, by the way, is Latin/Greek and refers to the underworld. In German Orca is simply called "Großer Schwertwal" (Large Sword Whale), referring to the large dorsal fin.
Reply | Report Abuse | Link to thisThe process behind the high enrichment of toxic substances in marine (and not only marine) top-predators is called "Biomaginification". The higher the trophic level - that is the higher up the food chain - an organism is positioned, the more toxic substances accumulate in its tissues. Plankton is at the lowest level, predators like seals, orca or tuna are at the highest level. Ironically we humans have become the ultimate top-level marine predator. As a result we get back whatever we poured into the sea. A beautiful reminder of the old insight that, after all, all things are connected. Somehow.