Identification and Quantification of Diets in Striped Bass in Atlantic Canada Using Traditional and eDNA methods.

Yang, Zhe¹, Russell Easy², Trevor Avery³, ¹Department of Biology, Memorial University of Newfoundland, St. Johns, Newfoundland, ²Department of Biology, Acadia University ,Wolfville, Nova Scotia, ³Departments of Biology and Mathematics & Statistics, Acadia University, Wolfville, Nova Scotia

Striped Bass (Morone saxatilis) feed widely on many fish and invertebrate species and occupy a high trophic level. In 2017 Striped Bass were found for the first time along the coast of Labrador, Canada potentially affecting local fisheries because Striped Bass may feed on commercially fished and at-risk species such as Atlantic Salmon (Salmo salar), Arctic char (Salvelinus alpinus), Cod (Gadus morhua), and Capelin (Mallotus villosus). Our objective was to use traditional and genetic methods to identify and quantify Striped Bass diets. Striped Bass carcasses were collected from recreational anglers and commercial fishers. Two methods were chosen: traditional analysis through dissecting stomachs and counting identifiable prey using morphological methods or examination of otoliths and molecular analysis whereby gastric eDNA was used to identify prey to species. In general, traditional analysis identified prey within a few days of being eaten, whereas molecular analysis widens the identification window to perhaps a week. Molecular tools such as qPCR may be useful to provide prey species proportions in diets. Our method relies on species-specific primers targeting conserved genes in suspected prey. Using various diet analysis methods provides a more reliable and robust picture of diets in these high trophic level predators.