Diet of Striped Bass in the Southern Gulf of St. Lawrence (Canada) with Emphasis on the Spring Spawning Aggregation

Abstract

The southern Gulf of St. Lawrence (sGSL) population of Morone saxatilis (Striped Bass) increased over 50 fold between the mid-1990s and 2013–2015, which led to interest in how their feeding might affect populations of commercially and recreation-ally important species. Information on the feeding habits of Striped Bass in all Canadian waters is scarce; therefore, a large number (n = 2220) of sGSL Striped Bass (19–86 cm fork length [FL]) stomachs were collected seasonally (2013–2015) in the Miramichi Estuary (where almost the entire population of individuals >30 cm FL aggregates during spring) and smaller estuaries that empty into the sGSL (summer only), by means of trap nets and by angling. Striped Bass collected during May–early June fed almost exclusively upon Osmerus mordax (Rainbow Smelt) but also consumed a few juvenile Salmo salar (Atlantic Salmon). Striped Bass collected in trap nets during 5–30 June mainly ate a mix of Alosa pseudoharengus (Alewife) and A. aestivalis (Blueback Herring); those collected by angling consumed aquatic insects and Crangon septemspinosa (Sevenspine Bay Shrimp). Striped Bass collected during July–September (30–45 cm FL) ate C. septemspinosa, Palaemon vulgaris (Common Grass Shrimp), and small estuarine fishes. The autumn sample was too small to be considered representative of the population; nevertheless, these fish (32–73 cm FL) ate juveniles of Microgadus tomcod (Atlantic Tomcod), Urophycis tenuis (White Hake), and Gadus ogac (Greenland Cod). The data collected herein would permit reasonable estimates of prey consumed by the sGSL Striped Bass population during spring and, for fish <45 cm total length, during summer, but estimation of annual prey consumption by the sGSL Striped Bass population requires additional data.