Publication Date

Spring 2023

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Scott Hamilton

Subject Areas

Ecology

Abstract

Canary rockfish are a profitable fishery resource that has failed and successfully recovered in the 21st century. This study aimed to evaluate their trophic ecology through stomach content and stable isotope analysis and relate these to their mercury concentrations, biological traits, and environmental conditions. Canary rockfish consume mostly krill and teleosts with their geographic location affecting the proportion of prey items, suggesting regional environmental effects: chlorophyll-a, relief, port, and depth impact dietary choices. Mean ??13C values (-17.18 ± 0.54) significantly increased in individuals residing in deeper depths, higher latitudes, higher productivity, and higher temperatures, and in sexually mature individuals. Mean ??15N values (15.26 ± 0.63) increased in individuals within higher latitudes, hotter temperatures, and elevated productivity. Mean calculated trophic level (3.52 ± 0.64) significantly increased in larger individuals, and those residing in more complex and cooler environments. Total mercury concentrations (0.04-0.50 ppm) significantly increased with ontogenetic development, weight, Fulton’s K, and latitude. Individuals that consumed higher proportions of teleosts and were larger, sexually mature, and resided in productive, nearshore, or northern environments possessed higher mercury concentrations. Future research should explore if resource allocation changes throughout the year for Canary rockfish, and if mercury concentrations do pose a threat to regional commercial and recreational fisheries.

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