Graduation Date
Winter 2024
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources: option Environmental Science and Management
Committee Chair Name
Dr. Alison O’Dowd
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Dr. Darren Ward
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Dr. Mark Henderson
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Name
Seth Ricker
Fourth Committee Member Affiliation
Community Member or Outside Professional
Keywords
Northern California, Humboldt Bay, Coho Salmon, restoration, off-channel restoration, ponds, salmon diet, invertebrate community, prey availability, survival, movement, salmon growth
Subject Categories
Fisheries
Abstract
Anthropogenic degradation of off-channel floodplain habitats has contributed to widespread declines in Pacific salmonid populations. These habitats are critical to the survival and growth of juvenile Coho Salmon during their first year of life. Restoring connectivity between mainstem and floodplain habitats could provide juvenile salmonids access to a mosaic of heterogenous foraging opportunities, with important consequences for salmonid growth and survival. I analyzed the diet, growth, and survival of juvenile Coho Salmon rearing in three restored off-channel ponds and adjacent mainstem habitats in Humboldt Bay tributaries to evaluate project performance. Juvenile Coho Salmon diet composition was significantly different among sites and habitats except for the two estuarine habitats. Some invertebrate prey taxa (i.e., Coenagrionidae, Isopoda, Dytiscidae, Mysidae, and winged adults) comprised large proportions of juvenile Coho Salmon diets in off-channel ponds, but were much less common or altogether absent in diets at other sites or habitats. Significantly higher growth of juvenile Coho Salmon was observed in a restored off-channel pond in estuarine habitat relative to the adjacent mainstem, but growth in constructed off-channel ponds was similar to growth in the adjacent main stem for freshwater ponds. Higher invertebrate biomass in juvenile Coho Salmon diets did not coincide with higher fish growth. Transition probabilities between mainstem and off-channel habitats indicated that juvenile Coho Salmon may have not been able to consistently move between these habitats at two out of three study sites. Differences in prey resource portfolios, fish passage, and density-dependent effects are likely drivers of variation in growth across sites and habitats, but inference on survival is limited at the project scale. These results can help inform future biological monitoring strategies for off-channel restoration projects.
Citation Style
APA
Recommended Citation
Stonecypher, Katherine Rose, "Diet, Growth, and Survival of Juvenile Coho Salmon (Oncorhynchus kisutch) in Off-Channel Restoration Projects in Humboldt Bay Tributaries" (2024). Cal Poly Humboldt theses and projects. 798.
https://digitalcommons.humboldt.edu/etd/798