Sábado, 17 de agosto de 2019

AGOSTO de 2019
Volumen XXXVI 
N° 376
ISSN 1852-317X


septiembre 2018


Orcas of the Pacific Northwest Are Starving and Disappearing

Orcas from pod J in Puget Sound just west of Seattle. The number of orcas in the area, listed as endangered since 2005, has dwindled to a 30-year low.CreditCreditElaine Thompson/Associated Press

SEATTLE — For the last three years, not one calf has been born to the dwindling pods of black-and-white killer whales spouting geysers of mist off the coast in the Pacific Northwest.

Normally four or five calves would be born each year among this fairly unusual urban population of whales — pods named J, K and L. But most recently, the number of orcas here has dwindled to just 75, a 30-year low in what seems to be an inexorable, perplexing decline.

Listed as endangered since 2005, the orcas are essentially starving, as their primary prey, the Chinook, or king salmon, are dying off. Just last month, another one of the Southern Resident killer whales — one nicknamed “Crewser” that hadn’t been seen since last November — was presumed dead by the Center for Whale Research.

In March, Gov. Jay Inslee issued an executive order directing state agencies to do more to protect the whales, and in May he convened the Southern Resident Orca Task Force, a group of state, tribal, provincial and federal officials, to devise ways to stem the loss of the beloved regional creature. “I believe we have orcas in our soul in this state,” he said. At another point, he wrote of the whales and Chinook salmon that “the impacts of letting these two species disappear would be felt for generations.”


The orcas are also facing a new threat. The recent agreement between the Canadian government and Kinder Morgan to expand the Trans Mountain Pipeline would multiply oil tanker traffic through the orcas’ habitat by seven times, according to some estimates, and expose them to excessive noise and potential spills. Construction is set to begin in August, despite opposition from Governor Inslee and many environmentalists.

In the late 1990s, there were nearly 100 of these giant whales in the population. Following the salmon, they migrate in the Salish Sea to the northern coast of British Columbia and often surface in the south at Puget Sound within sight of downtown Seattle, especially during the spring and summer months. The males, which can weigh up to 22,000 pounds, typically live about 30 years, and females, up to 16,000 pounds, survive longer — up to 50 or 60 years, although one J-pod member, Granny, lived to be 105 years old.


Not only are there fewer calves in recent years, but signs of inbreeding also point to a weakening population. In the 1970s and 80s, theme parks like Sea World captured nearly 4 dozen orcas from the region, possibly shrinking the pods’ gene pool. In the last three decades, just two males fathered half the calves in the last three decades, and only a third of the females are breeding, just once every decade instead of every five years. Researchers worry that reproducing females are aging out of the population, and won’t be replaced.

Some conservationists are concerned that the orcas’ decline is another sign of a marine ecosystem in collapse. Beginning in 2013, something known as “The Blob” — a gigantic mass of nutrient poor, extremely warm water — warmed the Pacific from Mexico to Alaska, as much as six degrees above normal. Several years ago, starfish succumbed to a wasting disease and vanished from tide pools.

Scientists suspect the biggest contributing factor endangering the orcas may be the disappearance of Chinook salmon, which is also endangered. The whales eat 30 a day, and hunting enough smaller prey requires a lot more energy.CreditSteve Martarano/U.S. Fish and Wildlife Service, via Associated Press

Much is still unknown about the plight of these orcas, but biologists and conservation managers have zeroed in on several main factors — and they are all connected.

The biggest contributing factor may be the disappearance of big king salmon — fish more than 40 inches long. “They are Chinook salmon specialists,” said Brad Hanson, team leader for research at the Northwest Fisheries Science Center here, part of NOAA. “If they could, they would eat Chinook salmon 24/7.” Orcas gobble 30 a day. Hunting enough smaller prey requires a lot more energy.

The underwater world in the region is also getting noisier, especially an area between the San Juan Islands and Vancouver Island called Haro Strait. It is one of the orcas’ favorite foraging grounds in the summer.

“It’s also essentially a big rock ditch where sound bounces off. When you add in commercial vessel traffic going to Vancouver, recreational boaters and whale watching operations, it’s a pretty noisy place,” Mr. Hanson said.

Researchers are studying noise there now. They believe the cacophony of ship traffic interferes with echolocation and makes it harder for the whales to locate their prey and to communicate prey location among themselves. It can also cause hearing loss.

In recent years, officials have expanded the distance which vessels, including whale watching boats and kayaks, must keep from the whales. And there is a voluntary no-go zone near the San Juan Islands.

“Just the presence of boats can cause the whales to spend less time feeding,” said Lynne Barre, of NOAA Fisheries, recovery coordinator for the orcas. “And it’s harder to communicate. They have to call longer and louder when boats are nearby.”