Diadromous Fish Assemblage Assessment and Food Web Characterization in the Saco River Estuary, ME

Significant population declines of diadromous fishes have impaired the productivity and trophic efficiency of shallow water estuarine ecosystems. Physical and biological factors influence the frequency and overall use of estuaries by diadromous fish, however little is known of these assemblages within small coastal rivers in the Gulf of Maine such as the Saco River estuary (SRE). During 2012 and 2013, weekly gillnet surveys were conducted at three sites from June-September to record fish species diversity and abundance in relation to environmental conditions (bottom temperature, salinity and dissolved oxygen). A static food web model will be created to estimate energy cycling, production, as well as ecosystem maturity and complexity. Standard outputs created from this modeling approach will be compared to similar systems where diadromous fish are known to maintain vital ecological processes and functions. From this model, multiple scenarios will be performed to investigate the role of diadromous fish as predators and prey within this estuary. Investigating trophic dynamics in coastal watersheds can provide managers a holistic understanding of complicated multispecies interactions on economically valuable and threatened species.