Hatcheries are an important part of the fishing economy of Southeast Alaska. But concentrating millions of baby salmon in net pens can lead to a buildup of fish waste. One Sitka researcher is trying to turn that problem into a solution, using kelp.
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Southeast Alaska isn’t exactly farm country, and Angie Bowers isn’t exactly a farmer. But she is cultivating a crop uniquely suited to coastal waters: sugar kelp.
And she’s growing a lot of it. Tucked away at the end of Deep Inlet, about ten miles by boat from downtown Sitka, Bowers has four 90-foot longlines seeded with sugar kelp. She took me to visit the site recently to see how the kelp was doing.
Bowers is an assistant professor in the fisheries technology department at the University of Alaska Southeast. All this seaweed is part of an experiment to see if kelp farming can be combined with fish hatcheries, creating benefits for both.
She chose this location in Deep Inlet because it’s right next to a hatchery release site. Northern Southeast Regional Aquaculture Association, or NSRAA, releases tens of millions of chum salmon here each year. These days, the fish are held in net pens, bulking up before their journey to the open ocean.
But as they’re swimming around in the pens, they’re producing a lot of organic waste — a.k.a. fish poop. Fish waste is a natural phenomenon of course, but the environmental impact is more concentrated when you’ve got millions of fish in a small enclosure. That can lead to lower oxygen levels in the water and the growth of harmful bacteria.
Bowers thinks seaweed might be able to help.
“In this case it would be taking up some of the fish waste, and also adding oxygen to the water, mitigating for ocean acidification,” she said.
It’s an example of one organism’s trash becoming another organism’s treasure — the excess fish waste contains just the sort of nutrients that kelp needs to grow.
Bowers says the kelp could also help the newly released hatchery fish, by giving them a place to hide from predators while they’re still pretty small. She’s also measuring how fast the kelp grows, to see if it gets a boost from being so close to a concentrated source of nutrients.
This project is also part of Bowers’ work as a masters student at Oregon State University. She had planned to use it as a teaching tool for her UAS students this semester, before in-person classes got cancelled due to the COVID-19 pandemic.
“And so originally this project was something that I wanted to put together to do the research side of things but then also to provide an educational tool to our students that were supposed to be here,” she said.
The experiment is still in process, so Bowers can’t say for sure what the results will be. But if it works, it could provide a model to help hatcheries operate with a lighter environmental footprint while benefiting the fish and growing a useful seaweed.
“It’s a win-win, for everybody involved, I’d say,” Bowers said.
One of the missing pieces, though, is people or businesses to farm kelp commercially in conjunction with the hatcheries. There are plenty of potential uses for kelp — food, fertilizer, even bioplastics — but Bowers says none of those are very lucrative markets right now, and Americans haven’t shown a big appetite for seaweed in general. And Bowers doesn’t think hatcheries would take on the extra cost and responsibility of farming their own kelp, seeing as they have enough work on their hands raising fish.
For her part, she’s trying to figure out what to do with her kelp once she pulls the lines in May.
“Maybe there’s gardeners out there, people that would be interested in taking some off my hands. I should have some to spare,” she said.
Bowers says managing the project on her own has been a lot of work, but also a good practice run for when she’s eventually able to bring students out here.
For now, her aquatic crop is growing fast during these long spring days, in amber waves of seaweed, just below the surface.