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Does a Bioenergetics Model Accurately Predict Fish Consumption by American White Pelicans? A Case Study on Walleyes in the Tamarac River, Minnesota
Author(s) -
Graham Jake D.,
Hafs Andrew W.,
Kennedy Anthony J.
Publication year - 2019
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1002/nafm.10287
Subject(s) - foraging , fishery , bioenergetics , optimal foraging theory , consumption (sociology) , population , biology , geography , ecology , demography , mitochondrion , microbiology and biotechnology , social science , sociology
The effect of piscivorous birds on fisheries is a growing concern for fisheries managers, especially when native birds consume large quantities of fish. The Red Lakes, Minnesota, fishery is one such example, where congregations of American white pelicans ( AWPE s) Pelecanus erythrorhynchos forage on spawning Walleyes Sander vitreus . We quantified AWPE consumption of Walleyes on the Tamarac River, a major tributary of the Red Lakes, by using empirical diet data collected from lethally sampled birds and separately by using a bioenergetics model. Furthermore, we evaluated the diet and foraging patterns of AWPE s on the river. Camera trap data revealed that AWPE s were foraging nearly completely nocturnally, likely in response to Walleye spawning migrations, with Walleyes accounting for 98% of AWPE diets. The empirical estimate of daily fish consumption from lethally sampled birds was not significantly different from the bioenergetics estimate. Monte Carlo simulations were used to provide estimates of uncertainty in annual Walleye consumption. Based on the simulations, all estimates of annual Walleye consumption between 2014 and 2016 represented < 1% of adult (age ≥ 3) Walleyes in the system and < 2.5% of adult Walleye natural mortality. This amount of Walleye consumption by AWPE s, at current population levels, does not pose a management concern.