Saturday, December 10, 2016

A Whale Of A Week

ESA protection could be on the horizon for rare whales: The National Marine Fisheries Service proposed the Gulf of Mexico Bryde’s whale for endangered species status under the Endangered Species Act this week. Just one unique and isolated Bryde’s whale population makes its home in a small area of the Gulf of Mexico, just off the Florida Panhandle. Today this small population is in danger of extinction as it faces the impacts of years of oil and gas-caused pollution in the Gulf as well as the threats of further oil and gas exploration and development. With fewer than 50 surviving whales, this tiny population simply cannot withstand further threats from offshore seismic exploration, oil extraction, and frequent oil spills as well as from shipping traffic noise pollution and ship strikes. Just over a year ago, Defenders of Wildlife advocated for listing this whale-it’s great to see NMFS take action!
SeaWorld CEO poster
Over 300 Layoffs Show SeaWorld's Ship Is Sinking Faster. SeaWorld has it all backward: It's the orcas and other imprisoned marine animals who actually would have benefited from losing their jobs this holiday. HELP ORCAS NOW.

Meet the Arctic’s New Top Predator—Killer Whales. Move over, polar bears. As sea ice melts, orcas are moving into the once-frozen Hudson Bay, preying on beluga whales and seals.
(Photo: Maggie Okituk/Reuters) 
There’s no doubt that melting sea ice in Hudson Bay is threatening endangered polar bears, but it might also be harmful to beluga whales, seals, narwhals, and other marine mammals, scientists are warning.

The reason? Melting ice caused by climate change is carving huge swaths of open water for longer periods of time, providing Atlantic killer whales more access to the bay and its rich stocks of prey.

“There has been an increase in the duration of open water by about 35 percent in the last 10 to 15 years, and killer whales can now come into the bay with little to hamper them as they move around,” said David Barber, the Canada research chair in Arctic system science at the University of Manitoba.

The open-water period in Hudson Bay used to last about two months each year, Barber said, but that has been extended to three months today, “and we’re on our way to four, five, and six months—and it will keep increasing as climate change starts to have more and more impact in the Arctic.”

Barber spoke by phone from Winnipeg, where he is attending ArcticNet 2016, a weeklong conference of some 800 Canadian scientists studying physical and biological systems in the Arctic, largely driven by changes in the ice cover.

Killer whales have historically avoided areas with ice because their large dorsal fins get caught underneath before their blowholes can breathe through fractures, Barber said. But ice-adapted whales, such belugas and narwhals, have much smaller dorsal fins and can breathe though little cracks in the ice.

Longer periods of ice coverage have always afforded protection for those animals, until weather patterns started shifting.

“If ice is in the area for long periods of time, it limits how far the killer whales can come in and how long they stay there,” Barber said.

In addition to climate change, freshwater entering the bay from two hydroelectric dams that generate power in the winter may be contributing to ice loss, he said.

Each summer, thousands of belugas migrate from the Hudson Strait on the eastern side of the bay to shallow estuaries on the western shore to feed and mate. The status of the western bay population, estimated at about 57,000, or 35 percent of the world’s total, was upgraded to “Special Concern” in 2004 by the Committee on the Status of Endangered Wildlife in Canada because of potential threats from shipping and hydroelectric development.

Reported sightings of killer whales, especially in the western part of the bay, have skyrocketed in recent decades, although there are no precise figures on how many more orcas are now entering the huge waterway each season.

Kristin Westdal, a marine biologist for the Pew Charitable Trusts’ Oceans North Canada, along with two colleagues, began interviewing hundreds of Inuit elders and hunters in 2006 about the historical presence of killer whales in the bay.

“They are a relatively new predator,” Westdal said. “Reports of sightings started in the 1950s or ’60s, and there’s not much history prior to that.”

The frequency of sightings has also increased. “Historically it was every few years, and now it’s every year, fairly consistently,” Westdal said, adding that some of the increase in sightings might be owing to faster and larger boats that can transverse extensive stretches of the bay.

Reports of killer whales preying on belugas are also coming in.

Westdal said a large number of belugas that had been tagged at Seal River were subsequently attacked by a killer whale pod.

“The belugas were in a tight cluster at the river’s mouth, and after the event they spread out along the coastline quite a ways north and then came back to their original habitat,” Westdal said.

“So they’re using quite a bit more of their range than we might have thought, which is important when looking at marine conservation in the region,” she said. “Their core habitat is not necessarily enough to protect that species, [as] this points to potential changes in distribution should killer whale attacks continue to increase.”

How much of a threat do the roving orcas pose to belugas?

“It’s a difficult question to answer because the population is so large,” Westdal said. “If there’s any effect, it’s going to be something we see in the long run. Still, a pod of 10 to 12 killer whales can do a lot of damage; they can certainly take down quite a few belugas. Over time, I think we’re going see some kind of changes in population and distribution.”

Westdal said there should be a similar impact on seals and narwhals.

Melting sea ice in the bay may be a boon to orcas, but it can also be hazardous. In 2013, a killer whale pod was trapped when a sudden freeze turned the open water into ice.

“Orcas are brilliant, but they don’t carry calendars,” said Shari Tarantino, president of the Seattle-based Orca Conservancy. “As long as there is no ice building up and food to eat, they will stay in the bay longer than they should.”

The Secret Dining Habits of Whales Revealed. Recordings of whale calls reveal where, when, and with whom whale species like to feast, and that could help conservationists save them.
(Photo: Vichan Sriseangnil/Getty Images)
Humpback, party of 12?

If the ocean’s feeding grounds had maître d’s, they might need to study up on which whales prefer to dine among their own kind.

A study published Tuesday in the journal Nature found that four species of baleen whales—humpback, minke, fin, and blue—segregate themselves when feeding on the northern edge of the 150-mile-long Georges Bank in the Gulf of Maine.

Each fall, billions of herring gather in the region to spawn. The rich food source attracts a number of whale and dolphin species, which converge on the area to feast.

“We find the vocal [marine mammals] divide the enormous fish prey field into species-specific foraging areas with varying degrees of spatial overlap,” the authors wrote.

The findings at the herring spawning grounds could have conservation implications for whale species.

“We now know exactly where the whales are going to be and how important this feed stock is for them,” said Chris Parsons, a professor of marine mammal biology and conservation at George Mason University, who was not affiliated with the study.

An easy fix, Parsons said, would be to ban all fishing in the area during those critical few weeks.

“You could call this their most important meal of the day,” he said. “It gives them enough energy to carry on with migration routes and reproduction. If you disturb them during that very small window, it’s going to have a massive effect on them.”

Researchers came across the phenomenon by accident.

In 2006, scientists from Northeastern University, the Massachusetts Institute of Technology, the Northeast Fisheries Science Center, and Norway’s Institute of Marine Research deployed 160 underwater hydrophones attached to a long cable and towed by a boat. They were attempting to detect the presence of herring over a two-week period across a swath of ocean more than four times the size of Massachusetts.

“We weren’t looking at marine mammals,” said study coauthor Purnima Ratilal, an associate professor of electrical and computer engineering at Northeastern University. “We were out there to study fish behavior and shoaling [when fish gather into densely packed groups] to further develop techniques for mapping fish instantaneously over a very large area.”

But the team started picking up the calls of a lot of marine mammals, “especially humpback whales,” she said.

After analyzing the herring data, the researchers turned their attention to the whale vocalizations. It took a few more years to sort out which calls emanated from which species and what they meant. But the team was able to determine where amid the feeding grounds the calls of a given whale species were coming from.

“What that implies is that those are the locations that are the preferred feeding areas for those species,” Ratilal said. “We found well-defined hot spots for each.”

Humpback whales gathered in two large clusters at each end of the spawning grounds, while minke, fin, and blue whales preferred to forage in the space in between. The investigators found that “feeding cries” coming from all four whale species increased exponentially at night, when herring form into shoals as a protective measure against predators.

So, why the separate dining areas?

“We’re not sure,” Ratilal said. “I don’t think they necessarily consciously segregate themselves.”

One likely reason is that humpback and fin whales hunt in groups, with humpbacks sometimes blowing air into a “bubble net” to corral their prey into a small area.

Water depths, which vary greatly along Georges Bank, is another possible explanation. Larger whales forage in deeper waters, while smaller species hunt in more shallow areas, Ratilal said.

One surprising finding was the increase in blue whale vocalizations at night. Blue whales, the world’s largest animals, are believed to feed almost exclusively on small crustaceans called krill. But in Georges Bank, they may be eating herring too.

“The high temporal correlation between blue whale call rates and herring densities obtained here suggest that it may be possible that blue whales are consuming herring,” the study authors wrote, “though this fish-feeding behavior has not been observed for blue whales.”

The study also provides new ammunition against the illegal whaling program conducted by Japan.

“Japanese scientists keep saying that whales are competing against each other, so they need to kill minkes to protect humpbacks,” Parsons said. “But natural selection has worked out a way for them not to compete. The Japanese argument that minke whales should be hunted because they’re eating all the fish is really simplistic.”
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