June 30, 2025
By Jack Winterhalter, Washington Sea Grant Hershman Fellow
The Port of Seattle’s maritime habitat team recently completed a pilot project to enhance herring spawning habitat in Elliott Bay. The Port has long demonstrated its strong commitment to environmental stewardship — from SEA Airport becoming the first U.S. airport to achieve Salmon-Safe certification to leading an array of estuarine and terrestrial restoration projects — but until now has not focused any efforts specifically on herring.
What are herring?
What exactly are herring, and why are they important to the region?
Herring are small, silvery fish that form large schools and are a vital component of the marine food web. Considered a “forage fish,” they are a critical food source for many other species including seabirds, marine mammals, and other fish such as salmonids. They are so important, in fact, that Puget Sound Partnership considers herring to be a “vital sign” — a measure of ecosystem health — necessary for the recovery and long-term wellbeing of Puget Sound. If herring are thriving, so is the ecosystem at large.
Above: Pacific herring (Clupea pallasii) are a small, coastal species of fish that form large schools and can be found from the Beaufort Sea in Alaska to Baja California in Mexico. (Image source: NOAA Fisheries).
Herring on the decline
Unfortunately, herring numbers in Puget Sound have been decreasing over the last 40 years. While Indigenous Coast Salish peoples have sustainably harvested herring for millennia, overexploitation by commercial herring fishing caused the population to start to decline in the 20th century. In addition to this overharvest, coastal development has reduced available habitat for spawning and rearing (e.g., eelgrass beds and kelp forests), making it especially difficult for herring numbers to bounce back. To date, no large-scale ecosystem-wide restoration efforts have been implemented in Puget Sound. Only a handful of smaller initiatives have taken place, with varying levels of success.
A collaborative approach
In partnership with the Muckleshoot Indian Tribe and Suquamish Tribe, the Port launched a collaborative pilot project to test potential methods for increasing herring spawning in Elliott Bay. Drawing from past efforts in the region by organizations such as Long Live the Kings and the Washington Department of Fish and Wildlife, as well as insight from Muckleshoot and Suquamish partners, the Port proposed and executed a spawning substrate enhancement pilot project at one of its properties, Jack Block Park, in southwest Elliott Bay.
Above: Two of the screens suspended from Jack Block Park at low tide.
By suspending artificial substrate made of biodegradable coir fabric (a material made from coconut husks) from the pier of Jack Block Park, the pilot project aimed to increase surface area in the intertidal zone for herring to spawn. Herring will typically spawn on eelgrass and macroalgae, such as kelp, so adding a material into the water column to mimic the aquatic vegetation that is not present at the site might encourage them to spawn there. In fact, this technique was partially inspired by the indigenous practice of placing evergreen tree boughs in the water to collect herring eggs for harvest.
Above: Evergreen boughs with herring spawn. (Image source: Julek Chawarski and Brian Starzomski, U.S. Fish and Wildlife Service)
Monitoring the results
After these “screens” were deployed, the maritime habitat team monitored them for about eight weeks, taking photos with an underwater camera to check their condition and to look for any eggs or other biological activity. After this monitoring period — which encompassed the typical spawning season for herring in Elliott Bay — the team removed the screens and inspected them more closely. While they found no herring spawn, they observed other marine life, including arthropods, crustaceans, gastropods, and small clusters of unidentified eggs.
Above: Close up photos of an egg cluster (left) and a sea slug (right) found on the screens.
What’s next?
It is challenging to predict exactly where herring will spawn within Elliott Bay each year, as many factors influence their behavior. Even though this pilot project did not result in herring spawning at Jack Block Park, it did demonstrate the potential of using low-cost, biodegradable materials as potential habitat enhancement in a complex urban watershed. This design could be improved and expanded upon in future work in Elliott Bay or elsewhere in Puget Sound. The Port continues to look for innovative ways to improve habitat conditions in the region and be good stewards of our shared natural environment.
Check out some of the Port’s other environmental stewardship such as our honeybees at SEA Airport and fish monitoring at the Duwamish River People’s Park and Shoreline Habitat.
Top image credit: "청어, ニシン, arenque del pacifico, arenque del pacífico, arenque-do-pacífico, arenque-do-pacifíco, aringa del pacifico, ch'ǒng-ǒ, fēi, gaaw, hareng du pacifique, hareng pacifique, herring, idaheeringas, iinang, iituuq, k'aaw, kapiselik, pacific herring" by Karolle Wall is licensed under CC BY-NC 4.0.
