Ice seal scientists conduct research in the Bering Sea

NOAA biologists presented some of their recent research and shared their 2022 field plans with participants at a Strait Science presentation late last month.

Calling in from NOAA’s Alaska Fisheries Science Center were Michael Cameron, who leads the Polar Ecosystems Program, and Erin Moreland, a senior ice seal biologist in the program.

The Polar Ecosystems Program studies all the ice seals: ribbon seals, spotted seals, ringed seals, and bearded seals, as well as the harbor seal.

Cameron explained that the program uses a multi-pronged approach to monitoring, studying and surveying seals in Alaska. The first prong, he said, is the most important, which is the residents of coastal communities. “You’re the eyes and ears, and are often the first folks to detect changes,” he said. “We really rely on all of those observations.” The next prong is the Alaska Department of Fish and Game, which works with hunters on analyzing samples among other things. Third is the partnership with NOAA as a whole, which conducts much broader surveys such as population dynamics and body condition. These surveys can be conducted aerially, from vessels, or with village participants.

Working on the NOAA ship Oscar Dyson at the marginal ice zone in the Bering Sea, researchers on this “ultra-quiet” vessel sample and tag seals. From 2005 through 2010 they went in the summer, but in 2014, 2016, and in 2018 they went in the spring, to focus on mother-pup dynamics. The purpose of these studies is to understand how many seals there are, the area of their seasonal movements, how healthy they are and how they are responding to habitat changes. Their 2022 research trip is currently underway, and in an email to the Nugget, Cameron said that they are expecting to arrive back in Dutch Harbor on April 25.

Using small boats to get to the ice floes, researchers sneak up on seals and net them. They attach satellite tags and take measurements and samples, which helps them understand health and range over time. A slide that Cameron showed in his presentation also said these efforts support other studies, such as unusual mortality events, UMEs for short, and harmful algal blooms, HABs. All of this helps them understand the impact of changing ecosystems. The 2014 and 2016 studies were conducted at the edge of the sea ice southwest of St. Matthew Island, but in 2018, that edge of the sea ice was several hundred miles further north, and the studies were conducted southeast of St. Lawrence Island. This year, satellite imagery shows they are west of St. Matthew Island, just shy of the dateline.

Early results from a meta study showed that body condition, defined as mass over length, and blubber thickness, measured through ultrasound, have declined from 2007 to 2018. This decline was seen in all the pups, and in the adults of the ribbon seals, but not in the spotted seals.

While the researchers were able to determine that this was the trend, they still need to figure out why. And, since the sample sizes are relatively small, they’re turning to drone-based photogrammetry to measure the length and guess the mass. They designed a system to count the pixels in the images, which can correspond to a specific distance when calibrated properly, and the researchers are out on the ice right now verifying the accuracy of this method.

“We believe this monitoring can be done without impacting hunting,” Cameron said, noting that their research will not take place inside of 12 nautical miles from the coast or 30 nautical miles from any whaling communities. They are avoiding other marine mammals, hunters, and are communicating daily with their plans.

In the second half of the presentation, Erin Moreland went into more specific details about joint surveys in the Beaufort Sea looking into the abundance of ice seals and polar bears. U.S. scientists conducted research on one side of the dateline while Russian partners did similar on the other side.

All these instrument-based surveys fly considerably higher than a drone, around 1,000 feet instead of 100 feet, but use an array of nine overlapping cameras: three thermal infrared cameras, three color machine vision cameras, and three ultraviolet cameras to detect polar bears. The three different light spectra are necessary to detect and verify “hot spots,” images which contain things which might be a seal or a polar bear.

Moreland said they are still working on the abundance estimates from their 2021 survey, but between April and June they conducted 28 surveys off the coast of Utqiagvik and Deadhorse, flying 11,569 miles, and taking almost one million images.

Students working on the project manually review a subset of these images and help train artificial intelligence and machine learning models to better detect them automatically.

It’s clear that they’re not surveying frequently enough, Moreland said, so in the future, they hope to integrate faster aircraft to reduce the time, work on detection models to get the information out faster, and integrate drones.

Cameron and Moreland are currently out on the ice conducting the 2022 survey. The daily updates from the ship say that high winds, heavy fog, and poor sea ice conditions have mostly prevented them from launching their small boats, but they have tested much of their equipment, and have been out on the floes with the seals when the weather has permitted. They will be back at Strait Science on May 12 to share what they saw.