From the Status of Walleye in Nipigon Bay Area of Concern: 2012
Prepared for: Environment Canada by: Terry Marshall, Marshall Consulting,
March 31, 2013
Nipigon Bay was designated an Area of Concern (AOC) in 1987 under the Canada-United States Great Lakes Water Quality Agreement.
The degradation of fish populations and the loss of fish habitat were beneficial use impairments (BUI) identified in Stage One of the Remedial Action Plan (RAP).
One of the fish populations that had been greatly reduced in numbers is that of Walleye (Sander vitreus). Overharvesting, degraded habitat, pollution and the construction of dams have been identified as possible factors.
There have been a number of research and assessment studies in recent years supported by the RAP process to learn more about Walleye and their use of existing habitat and to monitor their population recovery. Ontario Ministry of Natural Resources (OMNR) Nipigon District, OMNR Upper Great Lakes Management Unit, OMNR Aquatic Research and Development Section, Anishinabek/Ontario Fisheries Resource Centre and the Red Rock Indian Band have all contributed to this field work.
A Brief Overview of the Walleye Stocks in Lake Superior
The Walleye populations of Lake Superior have always been relatively small and widely scattered due to limited amounts of available habitat [Schneider and Leach 1977]. Within this lake they are confined to shallow embayments and the estuaries of moderate to large rivers which afford suitable conditions for spawning and the protection of juvenile fish.
Historically, the three largest stocks of walleye were found in Black Bay and Nipigon Bay, Ontario, and in the St. Louis River at Duluth, Minnesota [MacCallum and Selgeby 1987].
Smaller populations occur elsewhere around the lake, where smaller rivers and protected bays provide appropriate habitat.
Exploitation has been an ongoing source of stress to these walleye populations, with commercial harvest records going back to about 1870. In the early years, most of the harvest came from Michigan and Wisconsin waters, but from about 1920 onward harvest was largely from Ontario, with Black Bay contributing about 90% of the yield until the collapse of its walleye fishery in 1968 [Schneider and Leach 1977; Schram et al 1991]. In Nipigon Bay, an increase in the commercial walleye harvest occurred in the late 1940s as lake trout stocks declined through overexploitation and sea lamprey predation [Lawrie and Rahrer 1972].
Following a number of years of high harvest in the 1950s, the walleye population declined catastrophically with no harvest reported from 1966 onward. The Whitefish Bay stocks were also fished commercially at the Goulais River and in Batchewana Bay until their decline in the early 1970s [Schram et al 1991].
As a result of these intense fisheries, along with pervasive habitat degradation, walleye fisheries declined across Canada at this time. Country-wide, the annual catch of walleye fell from 9,090,909 kg in 1955 to about 2,954,500 kg in 1971 [Hartman 2009]
The populations that persisted all lacked a commercial fishery. This included the smaller Thunder Bay populations near the mouths of the Current, Kaministiquia, Pine and Pigeon rivers. Schram et al  reported these to have been only lightly fished by anglers with all populations appearing stable, although habitat loss has subsequently been identified as an issue [ Solec 2012]. The St. Louis population was the only large stock of walleye to survive this period and continue to be one of the healthiest stocks in the lake [Solec 2012]. Interestingly, it too was not commercially fished as the walleye had an objectionable flavour attributed to chlorophenolic products released from upstream paper mills [Margenau and Schram 1982; MacCallum and Selgeby 1987].