Correction: An earlier version of this article stated that the Chilkat Lake is on the Taku River, near Juneau. Chilkat Lake actually feeds into the Chilkat River system, near Haines. Two names are also misspelled in an earlier version of this article. The correct spellings of those names are Jodi Neil and Kevin McNeel, not Jodi Neal and Kevin McNeal. The article has been updated to reflect these changes.
The atomic age left its mark on Alaska’s rockfish.
Nuclear bomb testing in the Pacific in the ‘50s and ‘60s produced a carbon signature that can be seen in rockfish otoliths — thin inner-ear bones used to determine a rockfish’s age.
Kevin McNeel, a master’s student with the University of Alaska Fairbanks College of Fisheries and Ocean Sciences, uses these bones to check his work on shortracker rockfish in Prince William Sound.
In his Juneau lab on Tuesday, McNeel explained his work is a bit like counting rings on a tree to determine age. The nuclear connection is just one aspect of McNeel’s work.
“Part of my study uses the bomb radiocarbon — the atmospheric bomb testing signature — to help validate shortracker rockfish ages,” he said.
McNeel’s nuclear work is one of the many gems of scientific ephemera that might catch the eye of the curious at Friday’s science symposium at the University of Alaska Fairbanks College of Fisheries and Ocean Sciences.
Alaska’s environment is undoubtedly changing. From how the increase in the otter population might affect Southeast ecosystems to how Juneau’s boom in whale watching vessels might affect whales — UAF’s master’s students are trying to understand what the future holds for the water-bound environment.
From 9 a.m.-5 p.m., master’s students from Juneau will present research from their current master’s projects at the Juneau branch of the college on Lena Loop, next to the Ted Stevens Marine Research Institute.
The symposium is part of a two-day UAF Fisheries Days event. Saturday will feature an open house at the building, where visitors can enjoy touch tanks, activities and the open ears of scientists and staff.
Here’s a brief look at six master’s projects UAF students will talk about Friday:
Ali Schuler — how whale watching boats affect humpbacks
Juneau’s whale watching boom has been a boon for the visitor economy. But do whales appreciate the extra attention? Schuler wants to know — in both positive and negative terms — how whales respond to increased pressure from tour vessels.
Using several shore-based instruments near popular whale watching areas, Schuler is monitoring how whales might change their behavior when they’re being watched. Her research could help tour boats best avoid harassing the animals.
“The two main metrics that we’re looking at are behavioral changes and changes in movement. So things like respiration rate, dive time, as well as changes in speed and reorientation rate. How those may vary in the presence and absence of boats,” Schuler said.
“Juneau has a booming whale watching industry and it’s still growing. As more whale watching operators continue to enter the industry, how could that increased level of vessels have an impact?”
Schuler is also looking at how tour boats might influence visitor’s attitudes toward conservation. She’s combining her study into the potential negative impacts whale watching boats could have with one looking at how visitors change their attitudes following a whale watching tour.
“If there are any potential consequences, could these positive effects from conservation education maybe have a positive feedback loop? Maybe they could encourage the presence of regulations or even encouraging operators to operate in a more positive, whale-oriented industry,” Schuler said.
Ashley Bolwerk — otters and the ecosystem
After being hunted out of Southeast in the late 1800s, sea otter populations are booming. In the 1960s, the Alaska Department of Fish and Game reintroduced about 400 sea otters to Southeast. It’s not clear exactly how large the sea otter population has become in Southeast, but it’s understood that that population of 400 otters has grown substantially.
“The last estimate was about 25,000 individuals in Southeast Alaska,” Bolwerk said. “So it’s expanded quite a lot. They’ve radiated from initial reintroduction sites.”
Bolwerk is trying to understand how the otter pop might affect ecosystems on Prince of Wales Island. She studies intertidal rocky zones as part of a large group of faculty and students working under the umbrella of the Apex Predators, Ecosystems and Community Sustainability (APECS) project.
APECS project researchers want to establish the size of Southeast’s historic population of sea otters.
“That’s the golden question. The verdict is still out on what that population was,” she said.
Matt Callahan — juvenile sablefish ecology
Black cod, sablefish — it’s the same thing. That much biologists know, master’s student Matt Callahan explained.
What scientists are less sure about, and what Callahan is investigating, is how different environmental factors affect how sablefish grow.
Basically, he’s interested in “what environmental conditions are good for sablefish and what aren’t so good,” he said.
This could come down to the quality of the prey sablefish have to feast on. Another factor could be water temperature. He’s looking at both as part of his master’s work.
He tracks classes of sablefish as they grow older, trying to see if he can draw parallels between environmental conditions and recruitment, or survival.
“Hopefully, after my project, we’ll have a better idea what makes good growing conditions for juvenile sablefish,” Callahan said.
April Rebert — crab age and growth
Crabs molt, and when they grow those shiny new shells, they shed many of the markings of their previous life.
The facelift makes it hard to tell a crab’s age, April Rebert explained in her ADFG office on Tuesday. Currently, scientists don’t have a tried-and-true way of determining how old a crab is. They can estimate crab ages by size, but it’s an inexact science.
A young crab could just grow faster, while an older one could have just peaked out at a smaller size.
“It’s just like with people, the tallest person in this room probably isn’t the oldest,” Rebert explained.
So Rebert is looking for answers in crab stomachs. There’s some thought that the organ is the only part of a crab which doesn’t change when it molts, she said. So if they can tell how old a crab is by looking at the stomach, it could hold a key to aging crab more reliably.
Jodi Neil — how lake stocking affects sockeye salmon growth
Unique among salmon species, most sockeye spend their early years in lakes. One of those lakes is Chilkat Lake.
In the late 1990s and early 2000s, fishery managers stocked Chilkat Lake with sockeye in an effort to enhance numbers for fishermen. Neil is interested in how sockeye stocking on Chilkat Lake might have affected growth patterns.
“What was the effect on those juvenile fish living in the lake when all those extra fish were living in it, because they’re competing for space, they’re competing for food,” Neil said.
Fishery managers stopped stocking the lake after determining it was actually hurting fish growth. Neil’s work shows that might not be the case. By examining scale samples from ADFG data, she thinks sockeye stocking might not have the effect scientists previously thought.
She was expecting to see a negative effect on sockeye growth. What she found was the opposite, for a reason she’s not yet sure of.
“My hypothesis was that I’d see a decrease in growth,” she said. “Of course, I found the opposite.”
Kevin McNeel — aging rockfish
Rockfish can live over a hundred years, and with about three dozen species present in Alaska waters, there’s potential for misidentification.
But knowing exactly which species they’re looking at, and the age of each sample, is important for fishery managers, McNeel said. He’s trying to establish a new, software-aided method to better process bone samples from rockfish.
Computers process hundreds of images McNeel feeds it — each from a core sample of an individual rockfish otolith.
“It’s really high-level processing,” McNeel said. “It’s all free, online and accessible.”
McNeel’s software looks for patterns in the images and comes up with predictive models separating species indistinguishable to the naked eye.
“A lot of these are so similar, they’re hard to pick and choose. So having a software that can go through a lot of data and come up with predictive models,” helps fishery managers process samples a lot faster and more accurately, McNeel said.
• Contact reporter Kevin Gullufsen at 523-2228 and kgullufsen@juneauempire.com. Follow him on Twitter at @KevinGullufsen.
Jodi Neil, center, and Kevin McNeel, right, listen to April Rebert talk about her master’s project on crab age and growth in a Department of Fish & Game lab on Tuesday, April 3, 2018. The University of Alaska Fairbanks College of Fisheries and Ocean Sciences master’s students will be presenting their work in a public forum at the UAF College of Fisheries and Ocean Sciences building from 9 a.m.-5 p.m. on Friday. It is sponsored by the Alaska Chapter of the American Fisheries Society. (Michael Penn | Juneau Empire)
