North Pacific Anadromous Fish Commission

Technical Report 17

Table of Contents

Prey Selectivity and Diet Partitioning of Juvenile Salmon in Coastal Waters in Relation to Prey Biomass and Implications for Salmon Early Marine Survival

Authors: 
Elizabeth A. Daly, Richard D. Brodeur, Cheryl A. Morgan, Brian J. Burke, and David D. Huff

Abstract Excerpt:
Feeding conditions for juvenile salmon during their early ocean residence have been shown to be critical to their growth and survival, although direct sampling of their food availability has been limited (Brodeur et al. 2011). Increased understanding of prey dynamics during the early marine period of juvenile salmon could help us to better understand when increased competition may be occurring between salmon that eat at similar trophic levels. Juvenile coho (Oncorhynchus kisutch) and Chinook (Oncorhynchus tshawytscha) salmon typically consume age-zero juvenile fish, crab larvae, krill, and amphipods during their early marine residence, many of which are difficult to quantitatively assess using typical plankton gear (Brodeur et al. 2011). In May 2017 and 2018, as part of the National Oceanic and Atmospheric Administration’s Juvenile Salmon Ocean and Ecosystem Survey (JSOES), we collected juvenile salmon and their prey concurrently in coastal waters off Washington, USA by adding a fine mesh liner to the surface trawl net that has previously been used to sample juvenile salmon. The primary focus of the JSOES survey is to better understand the early marine period of Endangered Species Act (ESA) listed salmon and how changes in ocean conditions may impact their marine survival (Daly et al. 2013; Burke et al. 2013; Crozier et al. 2021). The goal of our study was to specifically examine prey environment, diet overlap, and how salmon utilized the available prey in 2017 and 2018.

*This is the first paragraph of an extended abstract. Download the full abstract below.

DOI:
https://doi.org/10.23849/npafctr17/53.56.

Citation

Daly, E.A., R.D. Brodeur, C.A. Morgan, B.J. Burke, and D.D. Huff.  2021.  Prey selectivity and diet partitioning of juvenile salmon in coastal waters in relation to prey biomass and implications for salmon early marine survival.  N. Pac. Anadr. Fish Comm. Tech. Rep. 17: 53–56.  https://doi.org/10.23849/npafctr17/53.56.