9781934874547-ch19

Trout and Char of the World

19: Trout as Native and Nonnative Species: A Management Paradox

Michael J. Hansen, Christopher S. Guy, Phaedra Budy, and Thomas E. McMahon

doi: https://doi.org/10.47886/9781934874547.ch19

Native trout are threatened worldwide by introductions of nonnative trout that in many cases are themselves threatened within their native range and historical habitats. This chapter focuses on this paradox and addresses how information gained to protect and restore a species in its native range can be used to suppress the same species outside its native range, where it may be invasive. We describe examples of three trout species, Lake Trout Salvelinus namaycush, Brown Trout Salmo trutta, and Brook Trout Salvelinus fontinalis, that are managed for the opposing goals of restoration versus suppression, in relation to their opposing roles as both native and nonnative species in aquatic communities. We also attempt to develop insights into how this information might be used to accomplish both seemingly incompatible ends.

The Lake Trout is native across much of northeastern North America, where the species was depleted in many habitats and has proven difficult to restore, but it has also been introduced across much of western North America, where the species has interacted negatively with other native trout species and has paradoxically proven difficult to control. In contrast to widespread introductions in North America, the Lake Trout has not been widely introduced beyond North America, and many introductions failed to persist (Crossman 1995). Consequently, examples of Lake Trout affecting native species are from western North America. Below, we review the paradox of restoring native Lake Trout in the Laurentian Great Lakes and suppressing nonnative Lake Trout in several lakes in the Intermountain West, USA (Table 1).