Status of American Shad in It's Introduced Range

The spread of invasive aquatic species constitutes a serious threat to global biodiversity, and has resulted in substantial environmental and economic cost.  Much of the research on the impacts of aquatic invasive species in North America has focused on the Laurentian Great Lakes region, with comparatively little attention afforded to the role of non-indigenous anadromous species in coastal ecosystems.  This reflects the relative rarity with which anadromous species successfully colonize coastal regions following purposeful introduction, and has been linked to the difficulty that anadromous species with complex life histories (e.g. Oncorhynchus spp.) have in adapting to novel environments.  However, where such introductions are successful, life history and phenotypic traits can evolve rapidly, and predictably.  Thus, from an evolutionary perspective, successful introductions of anadromous species are exceptional events, and provide opportunities to examine adaptations under new selective regimes.  It is perhaps surprising then that more focus has not been devoted by evolutionary ecologists to the examination of invasive American shad in the Pacific Northwest, despite their presence in the region for well over a century.  The goal of this synthesis is to review the current state of biological knowledge as it pertains to invasive American shad along the Pacific coast, and to highlight areas of research that require immediate investigation.