Citation: Barnes, C. L., Beaudreau A. H., and Yamada R. N. 2021. The role of size in trophic niche separation between two groundfish predators in Alaskan waters. Marine and Coastal Fisheries. doi: 10.1002/mcf2.10141.
Questions/Comments: Cheryl Barnes, [email protected]
To minimize negative effects of competition, predators must divide resources along one or more niche dimensions. Trophic niche separation is a principal method of resource partitioning in marine environments and is often assessed by quantifying diets of fishes with similar lengths. Taxonomic differences in allometric growth, however, suggest that the degree of gape limitation at a given body size varies among species. We studied resource overlap between two potential competitors in Southeast Alaska: Pacific Halibut (Hippoglossus stenolepis) and Arrowtooth Flounder (Atheresthes stomias). We quantified length–gape relationships and assessed effects of fork length (FL; cm), gape height (GH; mm), and gape width (GW; mm) on interpretations of trophic niche separation.
The files in this repository supply all data and code necessary to reproduce the tables and figures found in Barnes et al. (2021).
This repository provides detailed information about the methods used to quantify: a) species-specific morphometrics, b) interspecific differences in allometric growth, and c) the degree of dietary overlap and trophic niche separation between two groundfish predators in Alaskan waters. Results were used to make inferences about how various size metrics may impact interpretations of resource partitioning and the potential for competition among sympatric fishes. All data (morphometric, field-based, and diet) can be found in the 'Data' folder. R scripts are located in the 'Scripts' folder, separated according to analytical technique, and ordered similar to way in which findings are presented in the publication. Resulting plots can be found in the 'Plots' folder. All analyses were conducted using R v4.0.0 (R Core Team 2020).
This research was sponsored by the Pollock Conservation Cooperative Research Center (G00009488), the Rasmuson Fisheries Research Center associated with the University of Alaska Fairbanks, and two Northern Gulf of Alaska Applied Research Awards. The University of Alaska Southeast Sitka Campus provided facilities and additional support. Kenji Yamada (manager of Shelter Lodge) and Dean Murayama (owner of Anchor Point Lodge) donated considerable amounts of time and resources during data collection. Lodge captains Darryl Chow, Edmond Coccagna, Ken Fukada, Jason Helyer, Ben Huntley, Wayne Nasu, Brandon Rux, Ikaika Vivas, and Jon Wilson obtained the vast majority of samples and related field data. We would like to also recognize substantial contributions by research assistants Madison Bargas, Katie Brown, Helena Delgado‐Nordmann, Amanda Gile, Georgina Hunt, Zach Johanson, Aiden Kamber, Sawyer Link, and Harmony Wayner. Martin Dorn, Kirstin Holsman, Mary Hunsicker, Franz Mueter, and two anonymous reviewers offered comments to improve this manuscript.
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