Graduation Date
Fall 2024
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Fisheries
Committee Chair Name
Andre Buchheister
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
Rafael Cuevas-Uribe
Third Committee Member Affiliation
HSU Faculty or Staff
Keywords
Invasive species, Genetic biocontrol, Fisheries, Simulation modeling, Population modeling, Eel River, Pikeminnow, Sacramento Pikeminnow, TYC, Trojan Y Chomosome
Subject Categories
Fisheries
Abstract
The recent introduction and spread of Sacramento Pikeminnow (Ptychocheilus grandis) in Northern California’s Eel River Basin represents a significant threat and impediment to the recovery of several threatened native fish species. This study was undertaken to evaluate the Trojan Y Chromosome Strategy (TYC) for the extirpation of pikeminnow from the basin. TYC is a genetic biocontrol method that relies on the production and stocking of fish with YY sex chromosomes, which may be phenotypically male (YY male) or female (YY female). These YY fish produce all-male offspring when mating with their wild conspecifics and TYC can lead to the eventual extirpation of all wild-type females. To evaluate the strategy, I first investigated growth, maturity, and mortality of invasive Sacramento Pikeminnow in the South Fork Eel River to provide sex-specific life history information for this species. This was done by collecting scale (n = 297) and gonad (n = 57) samples and analyzing five years of pikeminnow suppression records from the basin. Results showed different growth, maturity, and mortality patterns for female Sacramento Pikeminnow compared to males. Female pikeminnow had a larger average standard length (440 mm) than males (259 mm) when mature, they matured at larger sizes and older ages than males, and they had a lower annual mortality rate. I then used this data to construct a mechanistic, individual-based population model to simulate a TYC Sacramento Pikeminnow stocking program. TYC effectiveness was found to be highly affected by the stock-recruitment productivity parameter, an unknown quantity for this species. If the species’ productivity is low, YY male stocking alone was found to be a promising option for eliminating their population. If their productivity is high, YY males alone were found to be a poor option, never achieving extirpation. However, stocking YY females was found to be effective in either case. Factors which improve the relative success of a TYC program included stocking more YY fish, higher YY survival in the wild, more concurrent manual suppression, and stocking YY females. Long-term population suppression in an open system (where complete extirpation is not possible) was found to be possible only if the species’ productivity is low and only if YY males alone are stocked. I conclude that stocking YY female Sacramento Pikeminnow for the species’ extirpation from the Eel River is an option which warrants further exploration and that there is a possibility of stocking YY males for population reduction, but additional research is needed to explore Sacramento Pikeminnow movement and stock-recruitment productivity.
Citation Style
American Fisheries Society
Recommended Citation
Juan, Alexander W., "Evaluating the Trojan Y Chromosome Strategy for the removal of invasive Sacramento Pikeminnow from the Eel River, CA" (2024). Cal Poly Humboldt theses and projects. 801.
https://digitalcommons.humboldt.edu/etd/801
Included in
Natural Resources and Conservation Commons, Population Biology Commons, Statistical Models Commons