The self-sustaining status of Georgian Bay’s trophy muskellunge (Esox masquinongy) fishery is owed in part to the widespread distribution of high quality coastal wetlands used as nursery habitat. The specific wetland features that promote the recruitment of young-of-the-year (YOY) muskellunge in Georgian Bay have not been clearly defined, and without such information, it is unclear to what extent an unprecedented period of sustained low water-levels (c. 1999), and/or shoreline modifications, will continue to degrade the suitability of nursery habitats used by muskellunge throughout Georgian Bay. In this thesis, I use data from two years of intensive sampling in two embayments of northern Georgian Bay to statistically differentiate between wetlands that were found with and without YOY muskellunge. By doing so, I have provided the first quantifiable definition of suitable nursery habitat for muskellunge in Georgian Bay. Muskellunge nurseries have a structurally complex community of submersed aquatic vegetation (SAV; e.g. Potamogeton richardsonii) within the water column (≤ 1-m depth) and a fish community that had abundant suitable prey (e.g. Cypinid species) and a scarcity of early-life predators (e.g. Perca flavescens). Some key aspects of the SAV community were governed by wetland's bathymetry, and this relationship makes it possible to model the effect of changing water-level scenarios on habitat suitability.
I translated these results into a management tool for fish management agencies by creating an Index of Nursery Habitat Suitability (INHS) that can be applied to other embayments in Georgian Bay to identify high quality early-life habitats for muskellunge. I developed two INHS models and applied them to an independent dataset from other regions of Georgian Bay, and found them to differentiate between sites that were known to be used by YOY muskellunge and those where YOY were absent. These were also able to track deterioration in habitat quality associated with the recent decade of low water levels. Both INHS models rely on variables based on robust ecological relationships known to favour YOY survivorship that can be readily collected by fish management agencies, and one INHS model does not require detailed information of the aquatic plant community. Both models were also designed to minimize the frequency of false negatives (suitable nursery sites misidentified as unsuitable) and false positives (unsuitable nursery sites misidentified as suitable). These INHS models should become an important tool that will complement harvest regulations to promote this economically and ecologically valuable, self-sustaining muskellunge population in Georgian Bay. / Thesis / Doctor of Philosophy (PhD) / The following Ph.D. describes how a period of sustained low water levels and shoreline modifications in Georgian Bay, Lake Huron, have impacted the coastal wetland habitat used by muskellunge during their early life. To counteract these adverse effects, the thesis provides a definition of the wetland features that promote the survival of young-of-the-year muskellunge in Georgian Bay. Included is a proposed management tool in the form of an Index of Nursery Habitat Suitability (INHS) for muskellunge that can be used to identify high-quality, early-life habitat of muskellunge. Furthermore, the INHS can be used to predict how the quality of this habitat responds to different water-level scenarios and to shoreline modification in Georgian Bay, and to guide rehabilitative efforts of degraded wetland habitat.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18098 |
| Date | 08 1900 |
| Creators | Leblanc, John Paul MR |
| Contributors | Chow-Fraser, Patricia, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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