Current Research
Distribution of summer-run steelhead in relationship to barriers and historical presence
In Northwestern California we have two distinct runs of steelhead, winter-run, which enter freshwater sexually mature in the late fall through winter, spawn and return to the ocean relatively quickly; and summer-run, which enter the river sexually immature in the late spring/early summer, spend the summer and fall months maturing and awaiting the return of the rains before spawning in winter. Summer and winter-run steelhead are, for the most part, spatially isolated from one another by barriers such as waterfalls or roughs (steep stretches of massive boulders), that are only passable at certain flows.
The Eel and Mattole Rivers are the southernmost extent of summer-run steelhead in North America. Human alterations to the landscape have resulted in more precipitous declines of summer-run steelhead, compared to winter-run, and summer-run are now on the verge of extirpation in California.
Genetic analyses over the past few decades have led to the conclusion that summer-run are more closely related to winter-run steelhead in their watershed than they are to summer-run in neighboring basins. This belief has resulted in the idea that if summer-run were extirpated, they could rapidly re-evolve from winter-run populations. More recent studies have found contradictory evidence, that run-timing (being a summer or winter-run) is controlled by a specific gene, and once summer-run are gone, they cannot be expected to re-evolve from winter-run on a human timescale.
Increasing understanding of the ecology, distribution and historical evolutionary advantages experienced by summer-run steelhead will help promote their persistence. This project is building off previous research conducted in the Van Duzen, Middle Fork and Upper Eel Rivers (click photo or title to link to the publication Kannry et al. 2020).
Investigation of the genetic basis of resident and anadromous life-histories of Coastal Cutthroat Trout and their hybridization with steelhead
Coastal Cutthroat Trout are an often-overlooked salmonid, as they do not undertake major ocean migrations, resulting in a smaller stature than other salmonids and having no commercial fishery. There is no previous research on the genetic expression of life history, i.e., being a resident trout that stays in freshwater or an anadromous, ocean-migrating individual.
A genomic region that partially controls whether a fish stays in freshwater or migrates to sea has been identified in steelhead. Understanding if a similar region of the Coastal Cutthroat Trout genome is strongly associated with life history will help inform management decisions, in basins where resident or anadromous life histories exist.
In addition, natural hybridization of cutthroat and steelhead is known to occur, but the amount and trends are not well understood. Current genetic techniques can accurately detect hybridization at the stream, individual, and genomic level. This project is building off previous research in the Smith River (click photo or title to link to the publication Rizza et al. 2023).
How we answer these questions
TRIB Researchers spend the summer and early fall hiking, biking and kayaking to selected sites throughout Northwestern California. For the steelhead research our watersheds of focus are the Mattole River, North Fork Eel, Mad River, Redwood Creek, mid-Klamath tributaries, Wooley Creek, Blue Creek and Smith River. Sampling sites are selected to obtain a broad spatial distribution throughout the basins, with a focus upstream and downstream of potential barriers.
The Coastal Cutthroat research is focused on lower Eel River tributaries, Humboldt Bay tributaries, North Fork Mad River, Little River, Redwood Creek, lower Klamath tributaries, Smith River and small ocean flowing streams between Redwood Creek and the Smith River. Sampling sites are selected where isolated, resident cutthroat populations exist above barriers; where putative anadromous cutthroat exist (in estuaries and lagoons) and where cutthroat and steelhead are hybridizing.
Sometimes snorkeling, often wading, we go out at night, with dipnets, when the fish are easier to capture and scoop or corral them into our nets. We then measure them and cut a tiny piece of their caudal fin. This tissue sample is dried and taken to the Miller Lab at UC Davis for DNA extraction and sequencing. Once we have the sequencing data we conduct numerous analyses using the UC Davis “farm cluster” computing system. We use the data generated to create figures and maps to visualize and share our results. We will present the results at aquatic/fish focused conferences and publish peer-reviewed literature. Stay tuned…
NEWS! Summer Steelhead and Spring Chinook Listed Under California Endangered Species Act
Our research was paramount in convincing the Fish and Game Commission of the rarity and imperiled state of these magnificent fish (click photo or title to link to press release). Now that we have established that, the real work of figuring out how to protect them begins.