Unraveling the Mystery of Herring in South Puget Sound: A Key to Salmon Recovery
In the Salish Sea, the health of salmon is closely linked with Pacific herring, a forage fish that plays an important role in the marine food web. Herring and other forage fish are a key food source for both juvenile salmon and larger predators, like harbor seals, that would otherwise feed on salmon.
Photo: Matthias Breiter-Minden Pictures
Within the Nisqually Reach, the ecology of Pacific herring has not been studied as much as it has been in other areas of Puget Sound. This is largely because there is not a currently known and monitored spawning stock in the Nisqually Reach, though oral histories of the Nisqually Indian Tribe tell of indigenous roe harvest by the Nisqually people within living memory. Additionally, there is limited information on the types and distribution of marine vegetation, potential herring spawning habitat, in the Nisqually Reach.
Beginning in 2021, the Nisqually Indian Tribe, Long Live the Kings and other partners began research and monitoring to address these data gaps. Each spawning season (mid-January through early June) we deploy evergreen trees and boughs as supplemental spawning substrate at a site historically known for herring roe harvest. The use of evergreen boughs and trees is an adaptation of a traditional practice that has been used by Tribes, First Nations, and Alaska Natives to harvest herring roe since time immemorial.
Illustration by Karen Gillmore (Snively & Williams 2016, p. 255)
Additionally, we have been surveying nearshore habitats throughout Nisqually Reach using the same methods that the Washington Department of Fish and Wildlife uses to monitor herring spawning events. In these “rake surveys,” we record the presence of available marine vegetation and look for herring eggs that would indicate a spawning event had occurred.
In 2022, we expanded our monitoring efforts to include sampling adult herring in the Nisqually Reach to understand population structure (age, sex, maturity and spawning stage) and their genetic stock identity. In 2023, we began working with Kwiáht to add an analysis of their diets and their contaminant loads to better understand food web interactions and potential toxic exposures for these fish.
We’re now starting our 5th year of monitoring Pacific herring in the Nisqually Reach. While we are pausing our tree and bough surveys until we find evidence of a herring spawning event, we are continuing to conduct rake surveys to look for herring spawn within the Nisqually Reach as well as characterize the availability and distribution of potential spawning habitat in this area.
If spawn is observed, genetic analyses of embryo samples will help us determine how this spawning aggregation is related to other known populations in Puget Sound. The genetic analyses of the adult herring we’re catching helps us understand which spawning populations are holding within Nisqually waters. The information we’re gathering on the diets and the toxic loads of these herring will help us understand the local food supply available to herring and salmon during their rearing stages and the pathways for toxic exposures that may be impacting their health.
Photo: Anthony Bucci
All the information we’re gathering in this ongoing monitoring effort is extremely useful in understanding the population structure and ecology of Puget Sound herring, helping inform ecosystem-based management decisions both for herring but also for salmon and steelhead recovery.
You too can help us better understand these important herring populations! See WDFW’s tips for spotting herring spawning events and join the invaluable network of citizen scientists who add to our knowledge of our productive Puget Sound ecosystem.
