Tuesday, January 5, 2010

Orcas of the Puget Sound: article looks at vanishing whale pods

Orcas, or if you prefer, killer whales - are one of the most distinctive cetaceans in the world. Though often associated with cold water regions, these intelligent and highly social predators are actually found in all the oceans. But probably nothing personifies the classic image of the orca as the pods of orcas that frequent the waters in Puget Sound in the northeastern Pacific Ocean - tall dorsal fins cutting through the blue water or whales fully breaching from frigid waters with picturesque forest shoreline backdrops.

But something ominous is taking place in this northern wilderness: the whales are slowly disappearing. There are several theories being studied that could explain the whales decline. But whether it's one cause or a combination, it all springs from one source: mankind.

Outdoor adventure writer Thayer Walker has written a very interesting article for the online Sierra Club Magazine about the decline of these orcas, known by researchers as the "Southern Residents." I had the opportunity to work with Thayer before and he is a gifted writer with a terrific appreciation for our natural resources, from geography to biology.

Thayer writes about the dedicated work of Ken Balcomb, who formed the Center for Whale Research and has been studying the orcas of San Juan Island in the Puget Sound for over 30 years. Balcomb has documented the gradual decline of the number of whales in the area, impacted in the '60s and '70s by the demand for orcas for aquariums and amusement parks. But what appears to be happening now points to possible poisoning from pollution and, perhaps in equal or greater measure, the decline of the whales primary food source - chinook salmon.

Changes in the salmon population, from either overfishing or man-made interference or damage to the salmon's fresh water breeding grounds, have either pushed the orca pods to search for new hunting grounds or, as unfortunately suspected, doomed the whales to starvation. Orcas are known for their highly complex social structures; whales will stay within a pod for life and will stake out territories that are often not easily abandoned.

But also pollution plays a critical role in this threatening scenario. Much like the chemicals that can accumulate in sharks and dolphins, the blubber in orcas can retain a variety of pollutants that would not necessarily harm the whale (unless absorbed in great quantities) as long as the whale remains vibrant and well-fed. However, when food is scarce the orca will begin to burn some of its fat, thereby releasing stored pollutants into its system which weakens the immune system and the overall health of the whale deteriorates.

The demand for fresh-caught salmon combined with development in the area - including dam building, forest-clearing, and urban growth - are all contributing to the decline of one of the oceans' most magnificent hunters, one that has cruised these frigid waters for eons but is now faced with a threat for which its cunning and intelligence provides no defense.

Kudos to Thayer for "Empty Sound", a great story. To read the entire article in the Sierra Magazine, click here.

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