“It smells really good,” said Brenna Haakinson. “Do you want to touch it? It’s very moisturizing — fish are really oily.”

Haakinson ran her fingers through the bucket of fine brown powder, which smelled of peat and dried fish. On closer inspection, there are small fish bones poking out. The material was produced at the Sitka Sound Science Center by dehydrating the remains of spawned-out salmon, part of a pilot program called Salmon Gardens that is testing dehydration as an alternative way to manage the carcasses of late-spawning chum and coho.

The goal is a shelf-stable fertilizer and compost product that puts salmon nutrients back into Alaska soil.

The dehydrator itself came from a Sitka craft brewery, Haakinson explained. About the size of a home washing machine, it can process roughly 250 pounds of salmon at a time, taking most of a day to turn the carcasses into two products: a liquid effluent and the ground material she held in her hands.

The solid material is the focus of the project. The Science Center hopes that it will be effective fertilizer and compost additives for gardens and farms.

“This is primo grade nitrogen and phosphorus,” Haakinson said. “This is gold. I already have lots of community gardeners calling me up.”

Salmon have always been crucial to the health of soils and gardens.

“We’re not doing anything new,” Haakinson said. In the past, Tlingit people would bury whole spent fish in their gardens to utilize their nutrients. However, due to concerns about smell, vermin and bears, salmon hatchery manager Haley Jenkins said it is not permitted to bury fish in the community garden.

The Science Center experimenters hope their product will create a more compact, versatile and shelf-stable way to bring this historic and organic fertilizer back to soils. 

In the book “Salmon in the Trees: Life in Alaska’s Tongass Forest,” author Amy Gulick explains that salmon carcasses are crucial to Southeast forests. For the trees along the creeks, spawning salmon are “delivery packages of super-concentrated nutrients.”

Bears and other animals in the forest eat and carry away half-eaten and half-rotten food and the released nutrients seep into the soil. Gullick writes that Sitka spruce trees grow up to three times faster along salmon streams compared to streams without salmon. 

The Science Center plans to try the material first as direct fertilizer, but might mix it into compost as well.

Debe Brincefield of the Sitka Farmer’s Market, where the Science Center will be advertising this product and educating the public about their program, said she is thrilled about the project. 

“We’re really excited to have them at the market; the project is fabulous!” Brincefield said.

The Science Center is a multi-faceted organization, with research, education and hatchery programs. The hatchery is relatively small compared to others, releasing 3.1 million chum, 3.1 million pink and 250,000 coho every year. 

Jenkins estimated that approximately 10,000 pinks, 15,000 to 20,000 chum, and 300 to 400 coho return to the hatchery annually. As the fish arrive, the hatchery workers euthanize them and harvest their sperm and eggs. This leaves them with a lot of carcasses to manage.

“Even once you collect all of (the) eggs,” Haakinson said, “(the hatchery) is still responsible for all the fish that are going to be coming in."

The center passes the bright salmon to the Sitka Tribe of Alaska, and in the peak of spawning season sells unusable decomposed salmon (“zombie” salmon) to Silver Bay Seafoods, which has processing lines that convert fish waste into saleable products such as dog and cat food. 

However, the Silver Bay processing plant closes at the end of the season — usually around September — and late spawning chum and coho are still returning to the hatchery through November.  That’s when the financial tables are turned. The fish carcasses are no longer a product the hatchery can sell for profit to a commercial processor. Instead, the center has the expense of disposal at sea.

Eliminating that cost would hopefully be a byproduct of the research, which is to turn all fish waste into agricultural fertilizer.

The Science Center’s Salmon Gardens is funded entirely by a one-year grant from the Renewable Natural Resources Foundation. 

The center hopes that if proven successful, the program can be modeled in larger, more traditional hatcheries elsewhere.