Winter ecology of striped bass (Morone saxatilis) near its northern limit of distribution in the Saint John River, New Brunswick

Abstract

Winter habitat selection by Striped Bass (Morone saxatilis) has been described as opportunistic, but due to the length and severity of winter at its northern range, winter habitats in the north are predicted to be restricted in distribution and carefully selected. Here we describe the locations and environmental conditions supporting winter aggregations of adult Striped Bass including periods under ice cover in the Saint John River, New Brunswick using acoustic telemetry. Striped Bass of both Saint John River (72%) and other ancestry (28%) were observed to overwinter within the river’s four mainstem lakes and embayments to which the individuals returned each fall. Most non-Saint John River ancestry Striped Bass were observed in habitats nearest the river mouth in winter. Striped Bass travelled to winter habitats from fall feeding locations from October to November, and only four tagged individuals departed the river at this time. Temperature, dissolved oxygen, and salinity conditions best described the winter habitats. By demonstrating the non-random distribution of Striped Bass during winter and identifying a gradient of habitat use by Saint John River ancestry Striped Bass in this northern river system, it is apparent that protection of these locations is critical for the long term conservation of Striped Bass populations in Canada.