Modeling Predator–Prey Linkages of Diadromous Fishes in an Estuarine Food Web

Kayla M Smith,James A Sulikowski,Carrie J Byron

doi:10.1080/19425120.2016.1194920

Abstract

AbstractHistorically, multiple species of diadromous fishes served as a coastal food source for commercially valuable nearshore predators. However, severe declines in diadromous fish populations in the nearshore Gulf of Maine (GOM) have impacted trophic dynamics and increased pressure on other estuarine-dependent forage resources. The objective of this study was to compare the trophic positions and interspecific interactions of diadromous fishes as predators and prey in relation to current GOM forage fishes. Empirical biomass data along with diet compositions and vital rates were used to construct a static model of a representative GOM coastal food web: the Saco River estuary (SRE) in Maine. A series of sensitivity analyses based on model outputs was performed to determine the trophic role of diadromous fishes in this estuarine food web. Model results suggested that juvenile marine transients played a greater role as forage species for SRE predators than did the anadromous Blueback Herring Alosa aestivali...

Highlights

Multiple species of diadromous fishes served as a coastal food source for commercially valuable nearshore predators
In the current study, an ecosystem approach was utilized to evaluate the trophic role of diadromous fishes in estuarine food webs
The results presented provide the first characterization of a food web in a Gulf of Maine (GOM) estuary by using Ecopath

Summary

Introduction

Multiple species of diadromous fishes served as a coastal food source for commercially valuable nearshore predators. Young-of-the-year (age 0) emigration and adult spawning immigration can impact the population dynamics of predator and prey communities (Schindler et al 2003; Walters et al 2009; Trinko Lake et al 2012) Migratory diadromous predators, such as the Striped Bass Morone saxatilis, transfer biomass across a series of estuarine systems, thereby helping to maintain connectivity and trophic structure across systems (Mather et al 2013). In addition to their ecological value, diadromous fishes serve as economically valuable and culturally important resources for historic and present-day coastal communities in the GOM (Link 2002; Hall et al 2012). In response to these declines, multiple diadromous species in the GOM are federally listed as endangered (Atlantic Salmon Salmo salar and Shortnose Sturgeon Acipenser brevirostrum) or threatened (Atlantic Sturgeon Acipenser oxyrinchus), are designated as National Oceanic and Atmospheric Administration (NOAA) species of concern (Alewife, Blueback Herring, and Rainbow Smelt Osmerus mordax), or are ecologically absent from many river systems (Saunders et al 2006; ASSRT 2007)

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