Federal fisheries scientists have published a special section in this month’s issue of that outlines some considerations for coming decades. A 91̽�� climate scientist helped biologists determine the long-term forecast for aquatic animals.

“When you look at projections for future climate change, there’s a big range of possible futures. And decision makers or biologists assessing impacts on a particular species want to know what’s the most likely future – they don’t want to use this huge range of uncertainty,” said , director of the UW-based .

Eight papers in the special section, led by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, include case studies for species ranging from chinook salmon to steelhead to 82 different types of coral.

Snover is lead author of a on choosing and using climate-change scenarios to inform policy for endangered marine species.

“We tried to distill what climate scientists know in a way that would be useful for conservation biologists,” Snover said.

Choice of scenario will depend on the species – a salmon that moves between mountain streams and the open ocean, for example, is different from an animal that scurries along a sandy beach or that clings to a rock at the bottom of the ocean. The paper gives a choose-your-own-adventure approach to picking an appropriate set of climate projections.

“People who are trying to make decisions that account for climate change are often bewildered or overwhelmed by the large number of scenarios that are available, and think in many cases that they’re too uncertain to be used,” Snover said. “We’re establishing a strategy for choosing from this vast array of scenarios, and strategies that are defensible in litigious situations like the (Endangered Species Act).”

The paper’s broad-based approach could also apply to land animals, she said.

The paper also includes a “reality check” table to counter some common misperceptions about climate models – for example, that they differ too much to predict any useful trends, or that their uncertainty could be reduced by somehow finding the best model to use.

Trends that are certain to affect marine species, Snover said, include increasing ocean acidification, warmer water temperatures and changes in level and timing of stream flows.

“Despite the significant uncertainty that remains about potential future climates, we know enough to assess impacts and incorporate that information into conservation decisions,” Snover said.

Co-authors on the paper are Nathan Mantua, a former 91̽��scientist now at NOAA’s National Marine Fisheries Service in Santa Cruz, Calif.; Jeremy Littell, a former 91̽��scientist now at the U.S. Geological Survey’s Alaska Climate Science Center in Anchorage; Michael Alexander at NOAA’s Earth System Research Laboratory in Boulder, Colo.; Michelle McClure at NOAA’s National Marine Fisheries Service in Seattle; and Janet Nye at Stony Brook University. The research was partially supported by NOAA through the UW-based .

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For more information, contact Snover at 206-221-0222 or aksnover@uw.edu.

Michelle McClure is corresponding author for the special section. See NOAA’s news release, ““

The ringed seal, currently under listing, builds caves to rear its young in snow drifts on sea ice. Snow depths must be on average at least 20 centimeters, or 8 inches, to enable drifts deep enough to support the caves.

“It’s an absolute condition they need,” said , an associate professor of atmospheric sciences at the 91̽��. She’s a co-author of the study, published in the journal .

But without sea ice, the platform that allows the snow to pile up disappears, ultimately reducing the area where the seals can raise their pups.

Bitz typically focuses on studying the area and thickness of sea ice. “But when a seal biologist telephoned and asked what our climate models predict for snow depth on the ice, I said, ‘I have no idea,'” she said. “We had never looked.”

That biologist was co-author Brendan Kelly of the National Science Foundation and he was curious about the snow depth trend because he was contributing to a governmental report in response to the petition to list the seals as threatened.

The researchers, including lead author and 91̽��atmospheric sciences graduate student , found that snowfall patterns will change during this century but the most important factor in determining snow depth on the ice will be the disappearance of the sea ice.

“The snowfall rate increases slightly in the middle of winter by the end of the century,” Hezel said. However, at the same time sea ice is expected to start forming later in the year than it does now. The slightly heavier snowfall in the winter won’t compensate for the fact that in the fall — which is also when it snows the heaviest — snow will drop into the ocean instead of piling up on the ice.

The researchers anticipate that the area of the Arctic that accumulates at least 20 centimeters of snow will decrease by almost 70 percent this century. With insufficient snow depth, caves won’t hold up.

Other climate changes threaten those caves, too. For instance, the snow will melt earlier in the year than it does now, so it’s possible the caves won’t last until the young seals are old enough to venture out on their own. In addition, more precipitation will fall as rain, which soaks into the snow and can cause caves to collapse.

The research is important for more than just the ringed seals. “There are many other reasons to study snow cover,” Hezel said. “It has a huge thermodynamic impact on the thickness of the ice.”

Snow on sea ice in fall and winter acts like a blanket that slows the release of heat from the relatively warm ocean into the atmosphere. That means deeper snow tempers sea ice growth.

In the spring, snow has a different impact on the ice. Since snow is more reflective than ice, it creates a cooling effect on the surface. “So the presence of snow helps sustain the icepack into spring time,” Hezel said.

To produce the study, the scientists examined 10 different climate models, looking at historic and future changes of things like sea ice area, precipitation, snowfall and snow depth on sea ice. The resulting prediction for declining snow depth on sea ice this century agreed across all of the models.

The new research comes too late to be cited in the about ringed seals that was written by the National Oceanic and Atmospheric Administration in response to the petition to list the ringed seal as threatened. However, it confirms results that were based on a single model that Bitz provided for the report two years ago. NOAA expects to soon.

The 91̽��scientists on this study were funded by the Office of Naval Research.

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For more information, contact Hezel at phezel@atmos.washington.edu or 206-321-5737 or Bitz at 206-543-1339, bitz@atmos.washington.edu.

, an oceanographer with UW’s , set out to find if any endangered passed through the Fram Strait, an inhospitable, ice-covered stretch of sea between Greenland and the northern islands of Norway. Only around 40 sightings of bowhead whales, which were hunted almost to extinction, have been reported there since the 1970s.

Stafford and colleagues put two hydrophones, or underwater microphones, on moorings attached to the seafloor in Fram Strait, leaving them there for as long as the batteries would last: nearly a year. Since the population of bowhead whales likely to pass through was thought to number in the tens, they didn’t anticipate much interesting data.

“We hoped to record a few little grunts and moans,” Stafford said. “We were not expecting to get five months of straight singing.”

Not only did they record singing nearly every hour of the day and night, they picked up more than 60 unique songs. A paper detailing their discoveries appears Tuesday (July 31) as the in Endangered Species Research and is openly accessible online.

The variety of tunes was so surprising that the researchers compared the whales’ song catalog to that of birds. “Whether individual singers display one, multiple or even all call types, the size of the song repertoire for… bowheads in 2008-2009 is remarkable and more closely approaches that of songbirds than other… whales,” they wrote in the report.

They have yet to learn why the whales sang so consistently last year.

Scientists believe that bowhead whale song comes from males during mating season. In most other kinds of whales, individuals either sing the same song their whole lives or all members of a population sing the season’s same popular tune. If bowheads are like the former, that would mean more than 60 males were in the Fram Strait. If the population is evenly split between males and females, there could have been more than 100 whales – far more than anyone thought comprised this population.

With further study, the scientists instead could discover that individual bowhead whales have a repertoire of songs that they sing during a season. That would be equally interesting because it would make the bowheads the only known whales to sing a variety of songs in the same season.

The findings also hint at the possibility of a rebound in bowhead whales.

“If this is a breeding ground, it would be spectacular,” said Stafford. “For such a critically endangered species, it’s really important to know that there’s a reproductively active portion of the population.”

In addition, since the whales are difficult to study given their year-round residence in the Arctic, virtually nothing was known about where they spend their winters. The research offers a clue about the whales’ migration path.

Only a handful of bowhead whale populations remain. The largest historic population, which includes the individuals studied for this report, once possibly numbered more than 30,000 members but was hunted to near-extinction from the 1600s through the 1800s. Commercial whaling reduced bowhead whale populations in other regions as well; combined, the four remaining populations are thought to number fewer than 10,000 members.

Bowhead whales are massive creatures. They grow to over 60 feet long, may live to 200 years old and can weigh 200,000 pounds. They use their huge skulls to break through ice as thick as 1.5 feet.

Bowhead whale song is unique in that the whales appear to sing with “two voices,” simultaneously producing high- and low-frequency sounds. The whales sometimes repeat the same tune for hours at a time.

Stafford and her colleagues deployed the two hydrophones 60 miles apart. They made 2,144 hours of simultaneous recordings from September 2008 through July 2009. In order to conserve battery power and take recordings for a longer period of time, the hydrophones worked for nine minutes out of every half hour.

The hydrophone in the west, covered in dense ice and in colder water, picked up far more singing than the one in the east, where there was spotty ice coverage and warmer water. The greatest frequency of song occurred in the darkest, coldest period.

“It’s clear there’s a habitat preference,” Stafford said. The thick canopy of ice may provide better acoustics than the loose pack ice and therefore might be favored by singing whales, she said.

“As Arctic sea ice declines, there may be some places like this that are important to protect in order to preserve a breeding ground for the bowhead whales,” Stafford said.

To answer new questions that the data opens up – including how many whales make up this North Atlantic population – Stafford hopes to do additional study.

Co-authors of the paper include Sue Moore and Catherine Berchok from the National Oceanic and Atmospheric Administration; Øystein Wiig of the University of Oslo; Christian Lydersen, Edmond Hansen and Kit M. Kovacs from the Norwegian Polar Institute; and Dirk Kalmbach with the Alfred Wegener Institute of Polar and Marine Research in Germany. The research was funded by NOAA and supported by the Norwegian Polar Institute and the Alfred Wegener Institute.

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For more information, contact Stafford at 206-685-8617 or stafford@apl.washington.edu