Managing Diadromous Species Along the Watershed-Ocean Continuum.

Ouellet, Valerie¹, Mathias J. Collins², John F. Kocik³, Rory Saunders³, Timothy F. Sheehan⁴, Matthew B. Ogburn⁵, Tara Trinko Lake⁴, ¹Integrated Statistics/ NOAA Northeast Fisheries Science Center, Orono, ME, ²NOAA Restoration Center, Gloucester, MA, ³NOAA Northeast Fisheries Science Center, Orono, ME, ⁴NOAA Northeast Fisheries Science Center, Woods Hole, MA, ⁵Smithsonian Environmental Research Center, Edgewater, MD

Diadromous fishes play important ecological roles by delivering ecosystem services (fisheries, marine-derived nutrients, predatory interactions, etc.) and influencing ecosystem productivity. They make crucial connections among ecosystems, including aerial and terrestrial. However, it is difficult to fully understand diadromous fish’s community cumulative benefits, as these species are mostly considered individually. Their interactions at a community level (e.g., predation, co-migration, habitat conditioning) and the connections between their ecosystem roles and functions (e.g., cumulative marine-derived nutrient contributions) are yet to be fully understood. Similarly, freshwater, estuarine and marine ecosystems are often considered independently, limiting understanding of the importance of connections across ecosystems. Not considering ecosystem interdependence and the importance of diadromous fishes as a community hinders the implementation of large-scale management necessary to increase ecosystem resilience and fish productivity across the range of these species. We developed a conceptual model, the Diadromous Watershed-Ocean Continuum (DWOC), that highlights how the diadromous community connects the different ecosystems they inhabit (marine, estuarine, and freshwater) and influence (terrestrial and aerial ecosystems) through migration, abundance, nutrient transfer, and other roles across a mosaic of habitats that includes headwater streams, lower rivers, and coastal streams as well as lakes, estuaries, nearshore, coastal shelf, and high sea habitats. DWOC uses ecosystem services to promote a more holistic understanding of the ecosystem connections made by these species. It provides a framework for discussions that can help identify research and management needs, discuss the trade-offs of different management options, and analyze what pressing questions that impede the implementation of ecosystem-based management.