de Kerckhove, Dak

This thesis aimed to address potential sources of bias in electronic fish tagging studies in order to advance the methods used by future studies. I first provided a review and meta-analysis of intracoelomic tagging effects in fishes, summarizing the existing literature and assessing the extent to which previously identified research gaps have been filled. I also included the first large-scale meta-analysis on tagging effects, examining the 2% rule using empirical evidence from a broad representation of all published studies. I then assessed the performance of a newly miniaturized predation-sensing acoustic transmitter (Innovasea V3D), demonstrating that V3D transmitters can mitigate predation biases by correctly identifying most predation events without false positives. I finally examined if immobilization via MS-222 or TENS alters the behaviours of fishes in the wild following tagging, and identified the time required for fish to re-establish normal behaviour following transmitter implantation.

Author Keywords: Acoustic telemetry, Electronic tagging, Fish ecology, Predation, Systematic review, Tagging effects

Walleye (Sander vitreus) are an ecologically and economically significant fish harvestedby recreational and commercial fisheries across Ontario. Adult Walleye are piscivores, but anecdotal evidence from anglers suggests that Walleye often target aquatic insects such as mayfly larvae (Ephemeroptera). My research examined the diet of Walleye caught from May to September in Lake St. Joseph in northern Ontario. I examined the stomach contents of angle harvested Walleye to identify the prey over two summers. Through morphological analysis of stomach contents, mayflies were found to be a significant prey source for Walleye, during larval emergence events in early summer, and to a lesser extent throughout the rest of the summer season. These findings are important for long term management of Walleye populations and associated resources. I also assess the potential and problems of Walleye management and research from my experiences of having worked with industry, government, and university partners on this project.

Author Keywords: alternative prey, Food web interactions, invertebrate, piscivore, Predator prey interactions

In order to effectively manage recreational fisheries, it is important to understand how the resource is being used. In this thesis, long-term creel census data, collected on Lake Opeongo in Algonquin Provincial Park, Ontario, Canada was used to assess fine-scale angler dynamics within a recreational Lake Trout (Salvelinus namaycush) fishery. The spatial distribution of angler reported catch locations of Lake Trout within the lake, was assessed using an Optimized Hotspot Analysis in ArcGIS. Areas of significant clustering of catch locations were revealed during all time periods and varied in size and location both seasonally and temporally. Cormack-Jolly-Seber models were used to evaluate the probability of individual angling boats persisting in the regional fishery and being detected on Lake Opeongo through time, as well as to examine the effect of angler travel distance and gas prices on participation parameters. Time-varying models revealed that the probability of an angler persisting in the fishery varied, while detection estimates remained stable. Travel distance had a negative effect on both parameters while increased gas prices only had a slight negative effect on detection estimates. Additionally, among Lake Opeongo anglers, angling avidity varied as did lake specific fishing experience. Average CUE was found to be higher among angling parties who visited the lake more often than fishing parties who visited relatively few times.