Diet reconstruction and niche of Lake Ontario top predators and corresponding prey species

• Main Author: Mumby, James Adam
• Format: Master Thesis
• Language: English
• Published: University of Windsor 2015
• Subjects: diet; forage fish; Lake Ontario; niche; salmonid; stable isotopes; Fish Lake; Cottus cognatus; Salmo salar
• Online Access: https://scholar.uwindsor.ca/etd/5515; https://scholar.uwindsor.ca/context/etd/article/6514/viewcontent/Mumby.pdf

Lake Ontario supports a diverse offshore fish community consisting of salmonids and forage fish with little known about the resource partitioning and habitat use of these species. To assess this, I used stable isotopes to determine the isotopic trends (forage fishes only), niche structure and overlap of both salmonids and forage fishes. I also estimated the salmonid trophic position (TP) and diet using stable isotopes. Forage fishes had high resource partitioning but was low between Myoxocephalus thompsonii and Cottus cognatus. Regional and temporal discrete subpopulations driven largely by nitrogen were only present in Alosa pseudoharengus, Osmerus mordax and Neogobius melanostomus. Salmonids had low resource partitioning, particularly Oncorhynchus tshawytscha and inhabit the offshore. A. pseudoharengus comprised a major proportion of the salmonid diet, followed by N. melanostomus while Salvelinus namaycush had the highest TP. Salmo salar restoration may prove difficult to due to high isotopic and diet overlap with other salmonids.