Graduation Date

Summer 2026

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources, option Fisheries

Committee Chair Name

Dr. Darren Ward

Committee Chair Affiliation

Cal Poly Humboldt Faculty or Staff

Second Committee Member Name

Dr. Jose Marin Jarrin

Second Committee Member Affiliation

Cal Poly Humboldt Faculty or Staff

Third Committee Member Name

Dr. Nicholas Som

Third Committee Member Affiliation

Cal Poly Humboldt Faculty or Staff

Keywords

Green sturgeon, Sturgeon, Humboldt Bay, Eel River, Mad River, Northern California, Habitat use, Acoustic telemetry, Aerial monitoring, Drone, Wind farm, Movement, Satellite tags, Breaching

Subject Categories

Fisheries

Abstract

Green sturgeon (Acipenser medirostris) are a long-lived, anadromous, iteroparous species that spawns in large West Coast North American rivers but ranges widely in the coastal ocean. For coastal California Native American Tribes, green sturgeon are a vital part of their cultural heritage and traditions, and central to their food security. Two genetically distinct population segments (DPSs) of green sturgeon are recognized in the United States, Canada, and Mexico; the southern DPS is listed as “threatened” under the Endangered Species Act and the northern DPS is considered of “conservation concern.” Although green sturgeon are known to use large estuaries and bays in the summer months, little is known about their seasonal behavior and spatial distribution in Humboldt County, California—a region undergoing rapid ecological change due to aquaculture, planned offshore wind development, and recent and upcoming dam removals. From August 2024 to December 2025, acoustic telemetry, drone and visual surveys, community science, and pop-up satellite archival tags were used to record the seasonal presence, habitat use, and movement patterns of adult green sturgeon from both distinct population segments within Humboldt Bay (Wigi), the Mad River (Baduwa’t), and the Eel River (Wiya’t) in Northern California. Twenty-three acoustically tagged green sturgeon, 7 northern DPS and 16 southern DPS, were detected in Humboldt Bay. Across 609 visual and drone surveys, 1,335 green sturgeon breaching events were documented exclusively in North Humboldt Bay. Across methods, detections and observations indicated strong seasonal and spatial structuring of habitat use within North Humboldt Bay, with activity peaking in late summer (July – September) and varying across tidal conditions. Although no acoustically tagged fish were detected in the Mad or Eel rivers, visual observations indicate interannual variation in both presence and spatial distribution of green sturgeon in these rivers. This project was conducted in collaboration with the Blue Lake Rancheria as part of the Northern California Tribal Fisheries Collaborative, a partnership between Tribal, university, state, and federal personnel, and is imperative for advancing our understanding of green sturgeon ecology and monitoring capabilities. By integrating complementary approaches, this study demonstrates the value of multi-method monitoring in an understudied system while supporting better-informed stewardship and management of Tribal and state natural resources in the face of habitat alteration and climate change.

Citation Style

Transactions of the American Fisheries Society

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