Pacific bluefin tuna, Thunnus orientalis, exhibits a flexible feeding ecology in the Southern California Bight

Pacific bluefin tuna, Thunnus orientalis, migrates from spawning grounds in the western Pacific Ocean to foraging grounds in the California Current System (CCS), where they are thought to specialize on high energy, surface schooling prey. However, there has been substantial variability in estimates...

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Bibliographic Details
Published in:PloS one 2022-08, Vol.17 (8), p.e0272048-e0272048
Main Authors: Portner, Elan J, Snodgrass, Owyn, Dewar, Heidi
Format: Article
Language:English
Subjects:
Animal feeding and feeds
Availability
Biology and Life Sciences
California Current
Cephalopods
Crustaceans
Diet
Ecology
Ecology and Environmental Sciences
Fisheries
Fishing
Forage
Foraging behavior
Management
Medicine and Health Sciences
Prey
Recreation
Regression analysis
Resource availability
Shellfish
Social Sciences
Spawning
Spawning grounds
Stomach
Taxonomy
Thunnus orientalis
Tuna
Variability
Variables
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Summary:Pacific bluefin tuna, Thunnus orientalis, migrates from spawning grounds in the western Pacific Ocean to foraging grounds in the California Current System (CCS), where they are thought to specialize on high energy, surface schooling prey. However, there has been substantial variability in estimates of forage availability in the CCS over the past two decades. To examine the foraging ecology of juvenile T. orientalis in the face this variability, we quantified the diet and prey energetics of 963 individuals collected in the Southern California Bight (SCB) from 2008 to 2016. Using classification and regression tree analysis, we observed three sampling periods characterized by distinct prey. In 2008, T. orientalis diet was dominated by midwater lanternfishes and enoploteuthid squids. During 2009-2014, T. orientalis consumed diverse fishes, cephalopods, and crustaceans. Only in 2015-2016 did T. orientalis specialize on relatively high energy, surface schooling prey (e.g. anchovy, pelagic red crab). Despite containing the smallest prey, stomachs collected in 2009-2014 had the highest number of prey and similar total energetic contents to stomachs collected in 2015-2016. We demonstrate that T. orientalis is an opportunistic predator that can exhibit distinct foraging behaviors to exploit diverse forage. Expanding our understanding of T. orientalis foraging ecology will improve our ability to predict its responses to changes in resource availability as well as potential impacts on the fisheries it supports.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0272048