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Gentoo Penguins
Photo Credit: DJ Jennings/Antarctic Photo Library
Gentoo penguins around the Antarctic Peninsula are having better success dealing with climate changes than their cousins, Adélies and chinstraps. There are various reasons why this may be, from their different foraging habits to a more varied diet.

A better strategy for survival

It’s not all bad news on King George Island. While the Adélies and chinstrap penguins struggle for survival, the gentoos, recognized by the wide white stripe extending like a bonnet across the top of its head, are thriving. Other researchers in the region, including Bill Fraser and Ron Naveen, have identified similar trends. [See stories: Local extinction and Losing count.]

Wayne Trivelpiece said the gentoos, larger than the Adélies and chinstraps, enjoy a more varied diet, relying less on krill than its smaller cousins do.

“These animals have done well,” he said. “They’ve hung in there, and seemingly increasing in numbers now, taking up some of the slack, if you will, of the Adélies and chinstraps.”

Diet alone doesn’t explain the gentoos’ success. They’re also the only species that doesn’t migrate in the winter to distant oceanic or pack ice habitats. Instead, as homebodies, they remain in the same hunting grounds but in much smaller colonies, usually with only a few hundred birds. Adélies and chinstraps can congregate in the hundreds of thousands.

The birds also mature differently, with Adélie and chinstrap chicks expected to forage on their own at about seven weeks of age. In contrast, gentoo adults support their young for up to 12 weeks, including the final couple of weeks when chicks go to sea where they can feed with adults. 

“This may allow young gentoos to learn a little bit about what’s going on out there, and still be sustained by being fed at night at their colonies,” Trivelpiece said.

Keeping krill in stock

The data on the penguins are important for managing commercial krill fisheries, one of the primary goals of CCAMLR and AMLR. At this point, Wayne Trivelpiece said, climate change is the primary cause in the decline of krill due to the reduction of sea ice.

May 2008 article External Non-U.S. government site by news agency Reuters said the annual commercial krill catch is only about 100,000 tons, well within what CCAMLR considers sustainable. That’s down significantly from the 1980s peak of 500,000 to 600,000 tons when the former Soviet Union fished the waters, according to Trivelpiece.

But there are signs the fishery could see more intense activity in the next few years. Krilloil is rich in omega-3 fatty acids, a popular dietary supplement found in not only pills but also milk and other foods. Fisheries also harvest the small crustaceans for special enzymes that can be used by surgeons to clean wounds, according to Reuters, while the pinkish remains after processing can be used as meal for salmon fish farms.

“The potential of the krill story is that the competition for protein of whatever form is becoming more and more acute,” Denzil Miller, Executive Secretary of CCAMLR, based in Hobart in southern Australia, told Reuters.

“I think in the next two to three years we are going to see a lot of changes in the way governments and the international community addresses problems of expectation around food security,” he added.

In addition, a Norwegian company has created a new way to harvest and process krill continuously, Reuters reported. Previously, it was hard to catch and then later process large amounts of krill because the enzymes inside them break down quickly, spoiling much of the catch.

CCAMLR currently has a 4 million-ton catch limit for Scotia Sea. Trivelpiece said one of the key pieces of conservation CCAMLR is working on is to divide that up into smaller management areas based on the four main island groups in the region. That will help ensure that the entire quota is not taken within the area adjacent to the islands where the penguins and seals would compete with humans for the krill.

“The fishery can’t concentrate their fishing in all in one area, where everybody believes if they were to do that it would adversely affect the predators,” he explained. “We’re trying to get all of this in place now, while the krill fishery is what all of us consider pretty modest.”

NSF-funded research in this story: Wayne and Susan Trivelpiece, have been funded for more than 30 years by NSF (Award No. 0443751 External U.S. government site), and by the Antarctic Ecosystem Research Division of NOAA’s National Marine Fisheries Service.

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