Applying Traditional Ecological Knowledge to recover a key species in the salmon food web
In the Salish Sea, the health of salmon is closely linked with Pacific herring. Herring and other forage fish are an important food source for both juvenile salmon and predators, like harbor seals, that would otherwise feed on salmon. Long Live the Kings is working with the Nisqually Indian Tribe, Port Gamble S’Klallam Tribe, and additional partners to understand and recover declining Puget Sound herring stocks. In a series of experiments, we’re testing whether a method adapted from traditional Indigenous techniques can be used to supplement spawning habitat and boost herring populations. More broadly, we are working to understand how habitat and predators are impacting herring spawning, and to improve herring management and recovery to benefit salmon.
Pacific herring are a key link in the Salish Sea ecosystem, with cultural and economic significance in addition to their critical role in the marine food web. Herring populations have been declining for decades, with several spawning stocks at a fraction of their historical numbers. Their decline poses a huge challenge for salmon recovery. The Salish Sea Marine Survival Project found a close link between forage fish abundance and juvenile Chinook salmon survival: forage fish like herring are both an important food source for salmon themselves, and an alternative prey source for predators like harbor seals (meaning that fewer salmon get eaten when herring are abundant).
Herring spawn in nearshore areas where their eggs attach to vegetation, like eelgrass and kelp. Many eelgrass and kelp beds in Puget Sound have been lost since the 1800s due to a combination of factors including shoreline development, pollution, and warming waters. Managers suspect that the loss of spawning habitat, along with poor water quality and predators, are major factors in herring declines. Until recently, however, there hasn’t been enough research to clearly understand Puget Sound herring populations, their spawning habitat, and how to recover them.
Coast Salish and Alaskan Tribes have a long-standing practice of sinking cedar and hemlock trees in nearshore waters during spawning season to collect herring eggs for harvest. Eggs stick to the tree branches as they would to eelgrass or other marine plants. In partnership with the Nisqually Indian Tribe and Port Gamble S’Klallam Tribe, we are adapting this practice as a potential tool for herring management and recovery.
In January, before herring spawning season begins, our team submerges evergreen trees and boughs at several depths in the Nisqually Reach and Port Gamble Bay. The evergreens are monitored regularly throughout the spawning season (January to June) to check for herring eggs. The Washington Department of Fish and Wildlife monitors herring spawn in Port Gamble Bay, a known spawning area, while our team checks for herring eggs while monitoring eelgrass beds and other potential spawning habitat in the Nisqually Reach.
Tribal histories report that herring used to spawn in the Nisqually Reach in South Puget Sound, but there has not been confirmed spawning in recent decades. In 2022, LLTK and the Nisqually Tribe began catching adult herring in the Nisqually Reach to determine their ages, sexes, and reproductive maturity, hoping to find mature herring that may be spawning nearby. Genetic analysis of these adult herring will help us learn more about herring populations in South Sound.
Port Gamble Bay is a known herring spawning site, although the number of herring spawning there has declined significantly since 2000. One suspected cause may be that birds and other fish are eating too many herring eggs. In our study, we hope to test whether we can improve egg survival by moving boughs with herring spawn into experimental enclosures in the bay designed to keep predators out.
In both study locations, our work with the Tribes and co-managers at WDFW is helping inform an ecosystem-level perspective on Puget Sound herring, and advance recovery of this key species to support salmon.
Years of Data Collected
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