Event Title

Functional response experiments evaluate the feeding response of juvenile Chinook salmon to varying densities of larval crab

Presentation Abstract

Larval crab are a key prey component in the diet of juvenile Chinook salmon (Oncorhynchus tshawytscha) during early summer growth period in the epi-pelagic habitats of the Salish Sea. The overall marine survival of juvenile Chinook is influenced by the variable availability of larval crab to their energy budget during this critical growth period. To determine how varying densities of available larval crab affect the feeding rates of juvenile Chinook salmon, functional response experiments were conducted in June and July at the USGS Marrowstone Marine Field Station sea water laboratory. Functional response experiments provide valuable insights into how species are affected by changes in densities of key prey and can be designed to evaluate how feeding capabilities change with body size of consumer, prey or both. We conducted feeding trials by exposing individual Chinook salmon (Size range 83-125 mm FL) to various environmentally relevant densities (13-545 megalops/m³) of larval crab megalops (carapace size 1.9-3.4 mm). Trials were run for twenty minutes after feeding was observed. Number of prey found in the mouth, esophagus and stomach for each fish was recorded. Results were averaged across all actively feeding fish within each trial. The response to varying densities was somewhat equivocal, but prey size and consumer size appeared to play a major role in feeding success.

Session Title

Posters: Species & Food Webs

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-119

Start Date

5-4-2018 11:30 AM

End Date

5-4-2018 1:30 PM

Type of Presentation

Poster

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 5th, 11:30 AM Apr 5th, 1:30 PM

Functional response experiments evaluate the feeding response of juvenile Chinook salmon to varying densities of larval crab

Larval crab are a key prey component in the diet of juvenile Chinook salmon (Oncorhynchus tshawytscha) during early summer growth period in the epi-pelagic habitats of the Salish Sea. The overall marine survival of juvenile Chinook is influenced by the variable availability of larval crab to their energy budget during this critical growth period. To determine how varying densities of available larval crab affect the feeding rates of juvenile Chinook salmon, functional response experiments were conducted in June and July at the USGS Marrowstone Marine Field Station sea water laboratory. Functional response experiments provide valuable insights into how species are affected by changes in densities of key prey and can be designed to evaluate how feeding capabilities change with body size of consumer, prey or both. We conducted feeding trials by exposing individual Chinook salmon (Size range 83-125 mm FL) to various environmentally relevant densities (13-545 megalops/m³) of larval crab megalops (carapace size 1.9-3.4 mm). Trials were run for twenty minutes after feeding was observed. Number of prey found in the mouth, esophagus and stomach for each fish was recorded. Results were averaged across all actively feeding fish within each trial. The response to varying densities was somewhat equivocal, but prey size and consumer size appeared to play a major role in feeding success.