Mid-Century Whaling Caused Marine Ecosystem Collapse, Scientists Say

For years, marine biologists in the North Pacific have been puzzled by the seemingly inexplicable decline of Alaskan seals, sea lions, and otters in the region. The problem wasn’t lack of food; in fact, these animals’ prey populations, such as sea urchins, are booming. Now, a group of researchers think they have the answer: a collapse in the food chain caused by the decimation of whales 50 years ago. After World War II, Japanese and Russian whaling fleets killed a half-million whales; in response, orcas, which used to prey on the other whales, turned elsewhere for food. That was bad news for seals, the scientists say — and when the seals grew scarce, it was bad news for sea lions, and then for otters. If the hypothesis is accurate, then the findings (which are being published today in the Proceedings of the National Academy of Sciences) suggest that conservation efforts must focus on entire ecosystems, rather than individual species.