Budy, P. G.P. Thiede, K. Chapman, and F. Howe. 2022. Potential conflicts among protected native birds and valuable sport fishes: pelican predation effects in a novel environment. Canadian Journal of Fisheries and Aquatic Sciences 79: 1–16. dx.doi.org/10.1139/cjfas-2021-0228. USGS FSP IP-125267.
Reservoirs are one example of novel ecosystems which have developed into popular sport fisheries; these systems are also becoming seasonal refuges for migratory birds including piscivorous species such as the American white pelican (Pelecanus erythrorhynchos). We determined (1) the proportion of Bonneville cutthroat trout (Oncorhynchus clarkii utah) and other species consumed by pelicans, (2) whether pelicans have an adverse effect on cutthroat trout spawning movement, and 3) the relative importance of pelican predation toother sources of fish mortality on Strawberry Reservoir, Utah, USA. Greater than 85% of the pelican diet samples consisted of Utah sucker (Catostomus ardens), 6% were Utah chub (Gila atraria) and 3% contained cutthroat trout. We estimated pelicans consumed £ 2,600 individual cutthroat trout (~ 1% of population) in contrast to over 42,000 sucker, 19,000 chub, and > 6,000 crayfish. Bird-related mortality rate ranged 1 – 6% for PIT-tagged adult cutthroat trout and 4 – 16% for stocked subadult cutthroat trout. Pelicans primarily consume abundant non-game fish, thus any management action taken to control pelican predation would need to be carefully weighed against the benefits of non-game fish removal and the protected status of pelicans.