Scientific Events and Seminars
Pacific Biological Station 2016 Seminar Series
For inquiries about the upcoming events, please email Karen.Hunter@dfo-mpo.gc.ca
Visitors: please sign in with the Commissionaire. Valid photo ID required. Dates and speakers subject to change. Talks are held in the Seminar Room at PBS at 1:30pm unless otherwise noted.
Speaker: Allan Debertin, PhD Candidate
Subject: Social-ecological Dynamics and the Persistence of the Lake Erie Gillnet Fishery
Date: Tuesday, January 26, 11AM Seminar Room
Abstract: Enigmatically, despite significant changes to the composition of species in the Lake Erie food web, fish harvesters on Lake Erie continue to persist in their role as top predators by harvesting high trophic-level fishes, suggesting that the system is ecologically stable. Simulations of human behaviour and fish population growth models were used to determine whether dynamical properties food-webs might mitigate negative effects of harvest as conventionally considered. Results from simulations predict that persistence of fisheries should be characterized by strong asymmetries in prey preference by harvesters dictated by price or quota, but less so in competitive strength among harvested species. These predictions were tested with long-term data on harvest, price and interaction strengths estimated from Bayesian model averages of four state-space stock assessment models of harvested species. Harvest from Lake Erie gillnets mainly comprise of native Walleye (Sander vitreus), Yellow Perch (Perca flavescens), White Bass (Morone chrsops) and non-native White Perch (Morone americana). Counter to conventional perceptions of effects of non-native species, there was little evidence that White Perch competed with commercially valued species. Furthermore, harvesters switched prey, between less-valued non-quota species and more highly valued quota species, consistent with the expectation under food web theory that prey switching is a stabilizing feature of food webs. This research demonstrates that food web theory and determining potential mechanisms of persistence could be used to better inform us of the consequences of multi-species management.
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