Salmon

Kelp Forest as Ocean Welcome

Sockeye, pink, coho, chum, and Chinook make a lovely alliterative list of the five salmon species (genus Oncorhynchus) found up and down the waterways, both fresh and salty, of the Pacific Northwest and Alaska. The iconic fish that Indigenous Tribes and First Nations have revered since time immemorial, that sport fishers pride themselves on hooking, and that most Americans assume can land on their dinner plate, has a remarkable life history from its birth far up freshwater streams, out into the open ocean, and back again to die after spawning in their natal waters. Salmon are anadromous—they transition from freshwater to salt water—and their transition into the marine environment is where the kelp forest and salmon stories entwines. This is a story being written by scientists right now. While there are many visual accounts of “tons of salmonids in the kelp beds!” there is very little data to quantify this relationship. Those who study and dive in the bull kelp forest, those who see seals break the surface from the kelp beds with an orange blur thrashing in the waves, those who count salmon prey and gauge fisheries health, know that the bull kelp forests provide habitat and migratory protection for salmon. But recording this is another challenge. Alaska is ground zero for this new science. Using more advanced GoPro timelapse videography, water sampled for eDNA, and SMURFS (a stacked lantern-like cage apparatus) to capture fish, data is being collected from wild bull kelp beds as well as from within bull kelp farms to quantify the salmon-bull kelp connection.

Each salmon species has a different timing on when they emerge from their birth rivers through estuaries and out into the ocean. Pinks are the smallest and most common salmon and have a life cycle of only a couple of years, so they emerge quickly. King, or Chinook salmon, are on the other end of the spectrum being the largest and longest lived. They might spend from one to three years in the rivers before entering the ocean. Bull kelp likes the ocean waters adjacent to river openings [see the Oregon Coast regional page] which gives young salmon emerging from the rivers a chance to hang out in the kelp forest and adapt to the ocean.

The kelp forest is known as a space of biodiversity so whether the young salmon’s food source is krill (euphausiids), shrimp, or smaller fish, the kelp forest is the place to find it. As young fish, they need to avoid predation by larger fish, even other salmon, and the kelp forest is a place to hide. And the bull kelp forest, a three-dimensional habitat of super photosynthesizers is a place of increased oxygen, an important factor for the respiration of young salmon processing a new kind of water through their gills.

There are plenty of anecdotal observations of salmon and bull kelp, but it is hard to survey salmon in kelp forests to quantify the association; a humanoid figure diving or snorkeling is sure to skew the number of fish in the vicinity. But the work is happening. In July 2022, a paper was published documenting the Chinook and coho salmon interactions with herring, sand lance, and surf smelt, in the bull kelp beds adjacent to the Elwha River in Washington State on the Strait of Juan de Fuca. Video was shot while snorkeling in these historic kelp beds which are still present and healthy. With the removal of the dams along the Elwha River, the bull kelp along the shores are thought to give refuge and hope for expanded salmon runs associated with this particular watershed.

In Alaska, salmon/kelp surveys are beginning to happen not only in the wild bull kelp beds along the southern coast, but also within the kelp farms that now proliferate around Kodiak, Juneau, and Prince William Sound. While the methodologies are still being developed, NOAA’s researchers at the Alaska Fisheries Science Center in Kodiak are taking joy in seeing plenty of adult pink salmon in wild bull kelp beds during one week’s dive, or salmon fry (babies) amongst the stipes and blades of a bull kelp farm during the following week’s dive. Fish and kelp go together. The data is coming.

The same is true in the Broughton Archipelago, just south in British Columbia, where fish farms have been removed so that native salmon populations can rebound. The collaborative team of the Broughton Aquaculture Transition Initiative (BATI) is surveying and assessing the bull kelp beds in the various waterways around the islands of the archipelago, knowing their potential as habitat important to salmon recovery. It is acknowledged that the association of salmon with kelp habitat hasn’t been decisively proven, but the kelp bed surveying work goes on. First Nations know, researchers know, and fisheries managers know that bull kelp health and salmon health are interwoven strands of the complex tapestry that is the healthy kelp forest.