Esox lucius

While northern pike and its relative muskellunge have somewhat different habitat preferences, they often occur together, either naturally or by human design. Northern pike spawn earlier, grow faster, and convert food better than muskellunge; they also eat young muskellunge, and tend to out-compete them for food and spawning sites whenever the two species occur together (Scott and Crossman 1973). Kerr and Lasenby (2001) cite several reports that suggest an inverse relationship between pike abundance and muskellunge spawning success. (Harvey, 2009)

The cross between northern pike and muskellunge produces the ‘tiger muskellunge’ which is stocked in some North American lakes for sport fishing. Despite different habitat preferences for the two species, hybridization can even result naturally when northern pike are introduced into waters containing native muskellunge; some female hybrids are fertile and capable of back-crossing (Becker 1983). (Harvey, 2009)

Kerr and Lasenby (2001) cite reports of hatchery pike affected by a number of parasites and pathogens, including lymphosarcoma. Transmission of this or any other disease between pike and other fish species is difficult to predict or prove, but it does constitute a potential impact. (Harvey, 2009)

Aguilar et al. (2005) cites predation on stocked trout in Lake Davis, California, where illegal introduction of northern pike has been well studied and where there is also a threat to the native chinook salmon Oncorhynchus tshawytscha in nearby watersheds. Northern pike may also be involved in the decline of native cutthroat trout O. clarki lewisi)and bull trout Salvelinus confluentus in Montana (McMahon and Bennett 1996; Muhlfeld et al. 2008). Perhaps the most exhaustive assessment of the potential impact of pike introductions on salmonids is in Alaska. The Southcentral Alaska Northern Pike Control Committee (2006) has reviewed the issue, and the following discussion is based on their report. The chief concern is predation on natural and supplemented populations of Pacific salmon Oncorhynchus spp., which could have both economic and ecological consequences given the salmon’s position as a keystone species that acts not only as a consumer of prey but also as food for mammals and birds, as well as a supplier of nutrients to terrestrial ecosystems. Rainbow trout maintained in many Alaskan lakes by annual stocking programs are also believed vulnerable to predation by illegally introduced northern pike. (Harvey, 2009)