BLACKFISH SOUND, QUEEN CHARLOTTE STRAIT, B.C. Bigger and bigger, with a puff and a blow, the orca surfaces, supreme in his kingdom of green.

Northern resident orcas like this one live primarily in the cleaner, quieter waters of northern Vancouver Island and Southeast Alaska, where there also are more fish to eat. They are the same animal as the southern residents that frequent Puget Sound, eating the same diet, and even sharing some of the same waters. They have similar family bonds and culture.

The difference between them is us.

The southern residents are struggling to survive amid waters influenced by more than 6 million people, between Vancouver and Seattle, with pollution, habitat degradation and fishery declines. The plight of the southern residents has become grimly familiar as they slide toward extinction, with three more deaths just last summer. Telling was the sad journey of J35, or Tahlequah, traveling more than 1,000 miles for at least 17 days, clinging to her dead calf, which lived only one half-hour.

Yet just to the north, the orca population has more than doubled to 309 whales since scientists started counting them in 1974, and has been growing ever since, at 2.2 percent per year on average.

For scientists seeking to better understand the southern residents’ troubles, the northern residents are like a control group, said Sheila Thornton, chief killer-whale biologist for the Department of Fisheries and Oceans Canada.

“Their environment has changed so quickly, over just two generations,” Thornton said of the southern residents. “To keep up with these changes is almost an impossible task. How do they survive in the environment we have created for them?”

The decline of the whales, a symbol of the Northwest, is also a warning, as climate change and development remake our region.

The northern residents live in not just a different place, but another world.

more at Source: Orcas thrive in a land to the north. Why are Puget Sound’s dying? – Chicago Tribune