Are We Losing Northern Pike Habitat in Georgian Bay, Lake Huron

Increased water temperatures and record low water levels associated with Global Climate Change (GCC) can significantly influence the availability of nearshore fish habitat in the Laurentian Great Lakes.  In eastern Georgian Bay, a number of large shallow embayments are used extensively by northern pike as spawning and nursery habitat. We surgically implanted 12 northern pike with radio-tags during spring 2011, and conducted a two-year tracking program to determine their movement patterns and centers of activity within Tadenac Bay, one of the least human-disturbed embayments in the area. We found that pike use shallow vegetated areas along the coastal margin, often in water temperature that greatly exceeds the optimal growing temperature (19 to 21°C), and frequently near the temperature at which pike ceases to grow (28°C). Based solely on thermal characteristics, amount of suitable habitat increases from July to September, but are confined to deeper depths, away from coastal marshes.  Historical temperature data are being assembled to explore if the apparent uncoupling of the realized and fundamental thermal niche has always existed, and what effects warmer temperatures and lower water levels may have on the northern pike population.