Graduation Date
Summer 2019
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Fisheries
Committee Chair Name
Mark Henderson
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Darren Ward
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Nicholas Som
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Name
Daniel Barton
Fourth Committee Member Affiliation
HSU Faculty or Staff
Subject Categories
Fisheries
Abstract
Accounting for life history diversity and overwinter survival of juvenile Coho Salmon is important to inform restoration and recovery efforts for this threatened species. Multiple seaward migration patterns of Coho Salmon have been identified, including spring fry migrants, fall and winter parr migrants, and spring smolt migrants. Previous studies have indicated that spring smolt migrants have low overwinter survival rates while they are rearing in upstream habitats, suggesting that freshwater overwinter survival may be one factor that limits smolt production. However, previous research did not account for the early emigration of fall and winter parr migrants from the study area, which most likely negatively biased their overwinter survival estimates. Furthermore, previous mark-recapture methods aggregated continuous detection data into course seasonal scales in order to estimate movement and survival. In an effort to refine previous methodology, I developed a multi-state model that allowed for estimation of early emigration and survival rates in space and time by having weekly time-varying occasions paired with discrete spatial states. I conducted extensive simulation trials to validate my use of the multi-state model on an existing 4-year PIT tag dataset in Freshwater Creek, California. Overwinter survival for spring smolt migrants was estimated as a function of average length at time of fall tagging for each year, and ranged from 0.87 to 0.90. Conditional on survival, early emigration estimates ranged from 0.34-0.40 annually. Results from the top model suggested that fish size during initial capture in the fall had a positive effect on overwinter survival of spring smolt migrants, and a negative effect on early emigration rates of fall and winter parr migrants. Additionally, streamflow had a positive effect on early emigration rates of fall and winter parr migrants. These results provide evidence that substantial numbers of smaller juveniles are emigrating early from upstream rearing habitat. This implies that previous estimates of low overwinter survival of Coho salmon could be due to high emigration rates to alternative rearing locations. Given the apparent diversity within the juvenile portion of the life cycle of Coho Salmon, multiple emigration patterns should be considered in the design of future research, monitoring, and restoration projects.
Citation Style
Transactions of the American Fisheries Society
Recommended Citation
Van Vleet, Nicholas Paul, "A time- and state-based approach to estimate winter movement and survival of juvenile coho salmon (oncorhynchus kisutch) in freshwater creek, California" (2019). Cal Poly Humboldt theses and projects. 299.
https://digitalcommons.humboldt.edu/etd/299