Feeding ecology of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus Mitchill, 1815 on the infauna of intertidal mudflats of Minas Basin, Bay of Fundy

A large feeding aggregation of Atlantic sturgeon occupies the inner Bay of Fundy during summer, presumably to forage on the intertidal mudflats. The feeding habits of Atlantic sturgeon were examined during summer 2011 in Minas Basin as description of diet is important for identifying critical foraging areas. Atlantic sturgeon demonstrated an overall preference for sandy tube-dwelling polychaetes (Index of Relative Importance (IRI)=99.7%). Major prey taxa included Maldanidae (Clymanella sp., 52.5%) and Spionidae, primarily the species Spiophanes bombyx (41.6%). Other prey items consumed included Phyllodocidae (Eteone sp., 2.1%), Nephtyidae (2.2%), Nereididae (0.7%), and Glyceridae including Glycera dibranchiata (0.6%). Seventeen additional taxa were identified in trace amounts (mean IRI=0.02%), including Corophidae and Mysidae. There was no significant difference in the number of prey items consumed and the fork length of the fish. Analysis of gut fullness with respect to tidal state indicated no significant difference between gut fullness on the flood or ebb tide. An overall preference for sandy tube-dwelling polychaetes may indicate that particular areas of the Minas Basin intertidal region are more important than others to these foraging fish. Considerable baitworm harvesting occurs during summer months in Minas Basin and could potentially create impacts with sturgeon consumers, both directly through competition for prey items and indirectly through change in sediment and benthic community composition.