Winter presence and temperature-related diel vertical migration of striped bass (Morone saxatilis) in an extreme high-flow passage in the inner Bay of Fundy

Abstract

During a multiyear fish tracking study, subadult and adult life stages of Shubenacadie River striped bass (Morone saxatilis) were detected throughout winter in the well-mixed, hypertidal waters of the Minas Passage, Bay of Fundy. Thirty-five percent of the striped bass tagged with Vemco V16 transmitters were detected by two Minas Passage receiver arrays. Transmissions were received on 82% of winter days (December to April) and by all receivers spanning the width of the passage. Tagged striped bass were detected largely within the top 20–40 m during the day. The extent of vertical migration to shallower waters at night showed a strong relationship with water temperature; however, there was no diel vertical movement pattern observed at water temperatures <1 °C. Our results demonstrate overwintering of a portion of the Shubenacadie River striped bass population in high-flow inner Bay of Fundy waters, which extends the northern limit of this species’ winter marine range. This study is also the first to describe the relationship between daily vertical migration by striped bass and low water temperatures. Both findings suggest an elevated potential risk of interaction with an in-stream tidal turbine facility in Minas Passage.