Interactions between native and non-native species in the Strawberry Reservoir ecosystem
Class
Article
Department
Wildland Resources
Faculty Mentor
Phaedra Budy
Presentation Type
Oral Presentation
Abstract
Predation and competition are natural ecological processes, though these interactions occasionally cause alarm among humans when ecosystem services are involved (e.g. popular fisheries) in highly managed systems. The population of American white pelican (Pelecanus erythrorhynchos) at Strawberry Reservoir (Utah) has increased dramatically in the last decade, as have the populations of Utah sucker (Catostomus ardens) and Utah chub (Gila atraria). Anglers and managers are concerned that predation by pelicans and competition from non-game fish species are negatively impacting the reservoir's Bonneville cutthroat trout (Oncorhynchus clarkii utah). My project focuses on non-game fishes and is part of a larger project that examines pelican predation potential on fishes, with an emphasis on cutthroat trout. Project goals included assessing potential for net bias, estimating age-class structure and body condition of non-game fishes, and determining the relative impact pelicans have on the different fish species of the reservoir. We caught multiple species of fishes using trap nets and gill nets, measured all captured fishes, and gathered pelican diet samples. Using a Kolmogorov-Smirnov test we determined that gillnets caught larger fishes. Based on length-weight regressions and Fulton's K factor, we observed higher body condition for Utah chub than Utah sucker. By identifying dominant modes of size-frequency distributions and comparing the modes to age-at-length data from previous studies, we estimated that captured Utah chub were age one and above while captured Utah sucker were age four and above. We evaluated the relationships between the number of pelicans and the catch-per-unit-effort of fishes at four different locations in the reservoir, and we observed no clear relationship. These results will provide useful information for fish population modeling in the future, for informing the next and final season of field data collection, and for critical management decisions for both birds and fishes in the reservoir.
Start Date
4-9-2015 9:00 AM
Interactions between native and non-native species in the Strawberry Reservoir ecosystem
Predation and competition are natural ecological processes, though these interactions occasionally cause alarm among humans when ecosystem services are involved (e.g. popular fisheries) in highly managed systems. The population of American white pelican (Pelecanus erythrorhynchos) at Strawberry Reservoir (Utah) has increased dramatically in the last decade, as have the populations of Utah sucker (Catostomus ardens) and Utah chub (Gila atraria). Anglers and managers are concerned that predation by pelicans and competition from non-game fish species are negatively impacting the reservoir's Bonneville cutthroat trout (Oncorhynchus clarkii utah). My project focuses on non-game fishes and is part of a larger project that examines pelican predation potential on fishes, with an emphasis on cutthroat trout. Project goals included assessing potential for net bias, estimating age-class structure and body condition of non-game fishes, and determining the relative impact pelicans have on the different fish species of the reservoir. We caught multiple species of fishes using trap nets and gill nets, measured all captured fishes, and gathered pelican diet samples. Using a Kolmogorov-Smirnov test we determined that gillnets caught larger fishes. Based on length-weight regressions and Fulton's K factor, we observed higher body condition for Utah chub than Utah sucker. By identifying dominant modes of size-frequency distributions and comparing the modes to age-at-length data from previous studies, we estimated that captured Utah chub were age one and above while captured Utah sucker were age four and above. We evaluated the relationships between the number of pelicans and the catch-per-unit-effort of fishes at four different locations in the reservoir, and we observed no clear relationship. These results will provide useful information for fish population modeling in the future, for informing the next and final season of field data collection, and for critical management decisions for both birds and fishes in the reservoir.