Spatial Ecology of Large Bodied Ichthyofauna in the Red River of the North Basin

Understanding spatial patterns and processes is essential for designing research studies, implementing management actions, and planning restoration efforts. The Red River of the North basin spans a broad geographic area where jurisdictional oversight is divided among several entities (Manitoba, CAN; North Dakota, USA; Minnesota, USA; South Dakota, USA), creating a mosaic of regulatory and functional process zones. Understanding the spatial ecology of freshwater fishes in this disjointed landscape is essential to address diverse life history requirements and the movement constraints imposed by anthropogenic structures. Long-term acoustic telemetry revealed that large bodied ichthyofauna employ a diverse range of movement strategies (i.e., migration, residency, dispersal, nomadism) throughout the basin. Lake Whitefish Coregonus clupeaformis (Mitchill, 1818) showed the highest likelihood of migratory behavior and a strong fidelity to spawning and overwinter locations. Lake Sturgeon Acipenser fulvescens Rafinesque, 1817, Bigmouth Buffalo Ictiobus cyprinellus (Valenciennes, 1844), Freshwater Drum Aplodinotus grunniens Rafinesque, 1819, and Walleye Sander vitreus (Mitchill, 1818) make annual displacements exceeding 350 km. Lake Sturgeon were the most rigid in their annual movement strategy, forming distinct groups with consistent movement patterns. Bigmouth Buffalo crossed anthropogenic structures and the international border more frequently than other study species. Burbot Lota lota (Linnaeus, 1758) and Channel Catfish Ictalurus punctatus (Rafinesque, 1818) movements were more restricted, typically remaining near tagging sites. Examination of Freshwater Drum demographic rates found no differences in mortality, growth coefficient, or asymptotic length among reaches in the United States. Growth estimates (K, Brody growth coefficient) align with studies conducted as far south as Alabama, while mortality rates (4–10%) and longevity (up to 62 years) reflect established latitudinal trends. Recruitment variability (recruitment variability index = 0.53) was associated with thermal and hydrologic factors, with positive associations to growing season degree days and negative associations to cold-season discharge and rise rate. These insights into both movement and population dynamics provide further understanding of species ecology, which can be used to improve management practices and direct future conservation actions. Advisor: Mark A. Pess