Date of Award


Publication Type


Degree Name



Earth and Environmental Sciences


Aaron Fisk


Tim Johnson



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Over 20 million native and non-native fishes are stocked into the Great Lakes annually as part of restoration initiatives and to support commercial and recreational fisheries. Bloater (Coregonus hoyi), a deep-water planktivore that was extirpated from Lake Ontario in the 1980s, has been consistently stocked in the lake since 2012 by Canadian and American natural resource agencies with the goal of producing a self-sustaining population. Previous research has highlighted challenges with stocking such as poor survival, attributed to high predation, potential maladaptive behaviour and barotrauma resulting from introducing a hatchery-reared species into a foreign environment. To address these survival challenges, bloater in this study were tagged with acoustic predation tags and stocked over three bathymetric depths in Lake Ontario (5, 50, and 100 m) to assess survival, behaviour, and to quantify sources of mortality at each depth. Coupling high resolution receivers (HR2) with predation tags permits fine-scale auto-estimation of predation-related mortality, in turn improving detailed survival estimates of stocked fish, specifically juveniles. Time-to-event modeling indicated a low survival rate (12%) in the first three-weeks post-stocking for individuals within the study area. Initial data suggested that predation played a dominant role in shallower depths, while mortality at deeper depths could be linked to barotrauma, although, no statistical differences were found in survival between the three depths. Relative position estimates demonstrated rapid dispersion of bloater post-release, with movement rates suggesting a tendency to migrate towards deeper waters. Continued investigation into the movement and predation of bloater post-release will be used to determine the survival of the stocked population. This enhanced understanding of the movement and mortality of stocked fish will play a crucial role in refining stocking strategies and assessing the overall restoration potential for bloater in Lake Ontario.