Position: Graduate Research Assistant
Where: University of Alaska Fairbanks When: January 2020-January 2021 Collaborators: Graduate Advisor USGS/UAF Dr. Jeff Falke, UAF Professor Dr. Peter Westley , ADFG Invasive Species Biologist Kristine Dunker, and many more Publication: www.proquest.com/openview/0b9c1b80a634e5190a1a54c83f2c0405/1.pdf?pq-origsite=gscholar&cbl=18750&diss=y Presentations: Cubbage, T., Falke, J., Bradley, P., Albert, M., Dunker, K., and P. Westley. 2021.Physiological drivers of invasion success in Alaskan Northern Pike (Esox lucius). Mat-Su Salmon Science & Conservation Symposium [virtual], 17 November, 2021. Cubbage, T., Falke, J., Kappenman, K., Bradley, P., M. Albert, and K. Dunker. 2021. Physiological performance of Northern Pike (Esox lucius): implications for management in invaded systems. Alaska Chapter of the American Fisheries Society Annual Meeting, Virtual Meeting, 22-25 March, 2021. Summary: Northern Pike are a widespread aquatic invasive species throughout southcentral Alaska and elsewhere in the lower 48 United States, where they predate upon and cause declines in native fish populations via predation. Understanding factors that enhance the invasion success of pike are useful from a practical standpoint to inform management actions, while also contributing to our understanding of invasion ecology and evolution. For this chapter of my master's research, I worked with project partners to evaluate if invasive populations of pike may benefit physiologically from abundant fish prey and certain habitat conditions relative to native pike in Alaska. Characterizing what conditions optimize the diet, growth rates, body condition, size-at-age, and age-at-maturity of pike can help mangers make more informed decisions that may apply broadly to other invasive piscivorous fishes as we try to protect intact native ecosystems on a global scale. During the summer of 2020, I collected invasive and native pike from river and lake habitats in packrafts, jet boats, and in waders via rod and reel angling and gillnets with the help of UAF laboratory technicians and the Alaska Department of Fish and Game. All fish were sacrificed and returned to the lab for a slough of physiological metrics to be quantified, including: body condition with bioelectrical impedance analysis and proximate composition analysis, fin and body morphology, diet using stomach content analysis and stable isotope analysis, growth rates using hard structure increment analysis, sex and maturity status, and metabolic activity using white muscle tissue enzyme assays. I used multivariate analyses to determine if invasive or native status and habitat type influenced physiological metrics, and synthesized results to tell an interesting story. Invasive pike had incredibly rapid growth rates, high lipid storage, and quick maturation relative to native populations, particularly when in warm lakes with abundant food. Flexible physiology across pike populations may allow them to continue to persist even after they have extirpated all native fish prey, making them particularly difficult to eradicate in the invasive range. However, characterizing conditions that promote pike success can prioritize protection of vulnerable habitats, through tactics such as selective barrier designs. Check out the full project background, methods, and results in my published master's thesis: www.proquest.com/openview/0b9c1b80a634e5190a1a54c83f2c0405/1.pdf?pq-origsite=gscholar&cbl=18750&diss=y |