Using Hydroacoustics to Investigate Prey Buffering During Atlantic Salmon Smolt Migration in the Penobscot Estuary, Maine, USA

Title:  Using Hydroacoustics to Investigate Prey Buffering during Atlantic Salmon Smolt Migration in the Penobscot Estuary, Maine, USA

 

Format: Oral

 

Authors:  O’Malley, Michael. NOAA’s National Marine Fisheries Service; 207-866-3758; Michael.O’Malley@noaa.gov

Saunders, Rory. NOAA’s National Marine Fisheries Service; 207-866-4049; Rory.Saunders@noaa.gov

Stevens, Justin. NOAA’s National Marine Fisheries Service; 207-866-4166; Justin.Stevens@noaa.gov

 Lipsky, Christine. NOAA’s National Marine Fisheries Service; 207-866-4667; Christine.Lipsky@noaa.gov

Kocik, John. NOAA’s National Marine Fisheries Service; 207-866-7341; John.Kocik@noaa.gov

 

Presenter: Michael O’Malley

 

Abstract: Prey buffering is hypothesized to influence the success of Atlantic salmon smolts as they migrate to the ocean.  The estuarine environment is a critical juncture during this migration, as smolt losses are high in a relatively narrow window of time and space.  Co-occurring species in the pelagic complex in the Penobscot estuary include river herring (Alosa pseudoharengus and A. aestivalis), American shad (A. sapidissima) and rainbow smelt (Osmerus mordax).  However, abundance of these species is historically low, theoretically reducing any prey buffering effect and consequently impacting smolt survival negatively.  We used multi-frequency split-beam techniques (38 and 120 kHz) to evaluate the potential for inter-specific prey buffer effects.  This survey method provides information on target size, relative densities, and spatial distribution of fish in the estuary when properly validated.  Our results conclusively demonstrate substantial spatial and temporal overlap of salmon smolts and river herring in an area of high smolt mortality, the first step in testing a prey buffer effect.  When coupled with recent findings from ultrasonic telemetry investigations, our hydroacoustic surveys provide preliminary insight into the role that the co-occurring suite of native diadromous fish play as salmon smolts transition to the marine environment.

Student presenter? No