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Contributed Talk

Session: : Behavior: Foraging And Diet 2

COS 26-1 - Trait-based indicators of resource selection by albacore tuna in the California Current Large Marine Ecosystem

Monday, August 7, 2023
3:30 PM – 3:45 PM PDT
Location: B112
Abstract: As global climate change drives reorganization in marine ecosystems, understanding how predators respond to variations in food webs is critical to forecasting future population dynamics. Prey availability is a key aspect mediating predator responses to changing environmental conditions through predator-prey relationships in marine systems. Trait-based frameworks are useful in simplifying complex foraging dynamics by identifying traits that recur across diverse taxa within a system to better understand resource use by predators. Here, we use datasets from 2005 to 2019 to evaluate diets of albacore tuna (Thunnus alalunga), a commercially valuable pelagic predator, in the context of prey availability estimates from shipboard surveys in the California Current Large Marine Ecosystem. We compare taxonomic and trait-based indicators of juvenile albacore resource use and selection within the ambient prey assemblage. Analyses reveal that albacore and trawl surveys sample different aspects of the pelagic system, with albacore consuming an overlapping but more variable taxonomic prey assemblage than sampled in trawls. Ecological traits mediating predator-prey interactions consistently distinguished albacore diets from assemblages sampled by trawls across years and regions. Albacore consistently consumed coastal prey that are schooling, undefended, silvered and countershaded, and have high energy density – suggesting that ecological mechanisms of albacore foraging processes may be conserved across time and space. We demonstrate that traits simplify taxonomically diverse predator-prey interactions and may be a valuable tool to facilitate predictions of prey resource use in changing environments.