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Article ; Online: Pacific bluefin tuna, Thunnus orientalis, exhibits a flexible feeding ecology in the Southern California Bight.

Portner, Elan J / Snodgrass, Owyn / Dewar, Heidi

2022 Volume 17, Issue 8, Page(s) e0272048

Abstract: 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 ... ...

Abstract	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.
MeSH term(s)	Animals ; Diet ; Ecology ; Fisheries ; Pacific Ocean ; Tuna/physiology
Language	English
Publishing date	2022-08-25
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2267670-3
ISSN	1932-6203 ; 1932-6203
ISSN (online)	1932-6203
ISSN	1932-6203
DOI	10.1371/journal.pone.0272048
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Juvenile Albacore tuna (Thunnus alalunga) foraging ecology varies with environmental conditions in the California Current Large Marine Ecosystem

Nickels, Catherine F. / Portner, Elan J. / Snodgrass, Owyn / Muhling, Barbara / Dewar, Heidi

Fisheries Oceanography. 2023 Sept., v. 32, no. 5 p.431-447

2023

Abstract: Juvenile North Pacific Albacore tuna (Thunnus alalunga) support commercial and recreational fisheries in the California Current Large Marine Ecosystem (CCLME), where they forage during summer and fall. The distributions of the commercial and recreational ...

Abstract	Juvenile North Pacific Albacore tuna (Thunnus alalunga) support commercial and recreational fisheries in the California Current Large Marine Ecosystem (CCLME), where they forage during summer and fall. The distributions of the commercial and recreational fisheries and estimates of forage availability have varied substantially over the past century. Time‐series quantifying Albacore diet can help link forage composition to variability in Albacore abundance and distribution and, consequently, their availability to fishers. Previous diet studies in the CCLME are of relatively short duration, and long‐term variability in Albacore diet remains poorly understood. We describe the diets of juvenile Albacore from three regions in the CCLME from 2007 to 2019 and use classification and regression tree analysis to explore environmental drivers of variability. Important prey include Northern Anchovy (Engraulis mordax), rockfishes (Sebastes spp.), Boreal Clubhook Squid (Onychoteuthis borealijaponica), euphausiids (Order: Euphausiidae), and amphipods (Order: Amphipoda), each contributing >5% mean proportional abundance. Most prey items were short lived species or young‐of‐the‐year smaller than 10 cm. Diet variability was related to environmental conditions over the first 6 months of the year (PDO, sea surface temperature, and NPGO) and conditions concurrent with Albacore capture (region and surface nitrate flux). We describe foraging flexibility over regional and annual scales associated with these environmental influences. Continuous, long‐term studies offer the opportunity to identify flexibility in Albacore foraging behavior and begin to make a predictive link between environmental conditions early in the year and Albacore foraging during summer and fall.
Keywords	Amphipoda ; Engraulis mordax ; Euphausiidae ; Sebastes ; Thunnus alalunga ; diet ; forage composition ; juveniles ; marine ecosystems ; nitrates ; oceanography ; regression analysis ; rockfish ; squid ; summer ; surface water temperature ; time series analysis ; tuna ; Pacific Ocean
Language	English
Dates of publication	2023-09
Size	p. 431-447.
Publishing place	John Wiley & Sons, Ltd
Document type	Article ; Online
Note	JOURNAL ARTICLE
ZDB-ID	1214985-8
ISSN	1054-6006 ; 1361-9470
ISSN	1054-6006 ; 1361-9470
DOI	10.1111/fog.12638
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Using low volume eDNA methods to sample pelagic marine animal assemblages.

Dan, Michelle E / Portner, Elan J / Bowman, Jeff S / Semmens, Brice X / Owens, Sarah M / Greenwald, Stephanie M / Choy, C Anela

PloS one

2024 Volume 19, Issue 5, Page(s) e0303263

Abstract: Environmental DNA (eDNA) is an increasingly useful method for detecting pelagic animals in the ocean but typically requires large water volumes to sample diverse assemblages. Ship-based pelagic sampling programs that could implement eDNA methods ... ...

Abstract	Environmental DNA (eDNA) is an increasingly useful method for detecting pelagic animals in the ocean but typically requires large water volumes to sample diverse assemblages. Ship-based pelagic sampling programs that could implement eDNA methods generally have restrictive water budgets. Studies that quantify how eDNA methods perform on low water volumes in the ocean are limited, especially in deep-sea habitats with low animal biomass and poorly described species assemblages. Using 12S rRNA and COI gene primers, we quantified assemblages comprised of micronekton, coastal forage fishes, and zooplankton from low volume eDNA seawater samples (n = 436, 380-1800 mL) collected at depths of 0-2200 m in the southern California Current. We compared diversity in eDNA samples to concurrently collected pelagic trawl samples (n = 27), detecting a higher diversity of vertebrate and invertebrate groups in the eDNA samples. Differences in assemblage composition could be explained by variability in size-selectivity among methods and DNA primer suitability across taxonomic groups. The number of reads and amplicon sequences variants (ASVs) did not vary substantially among shallow (<200 m) and deep samples (>600 m), but the proportion of invertebrate ASVs that could be assigned a species-level identification decreased with sampling depth. Using hierarchical clustering, we resolved horizontal and vertical variability in marine animal assemblages from samples characterized by a relatively low diversity of ecologically important species. Low volume eDNA samples will quantify greater taxonomic diversity as reference libraries, especially for deep-dwelling invertebrate species, continue to expand.
MeSH term(s)	Animals ; DNA, Environmental/genetics ; DNA, Environmental/analysis ; Aquatic Organisms/genetics ; Aquatic Organisms/classification ; Biodiversity ; Seawater ; Fishes/genetics ; Fishes/classification ; Zooplankton/genetics ; Zooplankton/classification ; Ecosystem ; Invertebrates/genetics ; Invertebrates/classification
Language	English
Publishing date	2024-05-15
Publishing country	United States
Document type	Journal Article
ZDB-ID	2267670-3
ISSN	1932-6203 ; 1932-6203
ISSN (online)	1932-6203
ISSN	1932-6203
DOI	10.1371/journal.pone.0303263
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Gelatinous cephalopods as important prey for a deep-sea fish predator

Chen, Rachel S. / Portner, Elan J. / Choy, C. Anela

Mar Biol. 2022 Dec., v. 169, no. 12 p.155-155

2022

Abstract: We quantified cephalopods consumed by longnose lancetfish (Alepisaurus ferox, n = 1267 stomachs containing cephalopod remains) from 2009 to 2018 in the central North Pacific Ocean (between 0–35° N and 135–175° W). When cephalopods identified from beak ... ...

Abstract	We quantified cephalopods consumed by longnose lancetfish (Alepisaurus ferox, n = 1267 stomachs containing cephalopod remains) from 2009 to 2018 in the central North Pacific Ocean (between 0–35° N and 135–175° W). When cephalopods identified from beak remains in the stomach contents were included in diet analyses, clear increases in the abundance of gelatinous taxa and the inferred foraging depths of lancetfish were evident. Ontogeny in cephalopod consumption was evident for lancetfish, corroborating past diet studies. Small lancetfish (fork length < 97 cm) fed on smaller, muscular cephalopods from shallow habitats (0–500 m, e.g., Ommastrephidae, Onychoteuthidae), while large lancetfish (fork length ≥ 97 cm) consumed larger, gelatinous cephalopods from deeper waters (depths greater than 500 m, e.g., Amphitretidae, Cranchiidae). Cephalopod beaks were more abundant in the diets of large lancetfish, representing 37.8% of identified cephalopods, numerically. Although beaks likely remain in stomachs longer than soft tissues, they did not simply accumulate with increasing predator size. Cephalopods identified from beaks were also significantly larger than those identified from soft tissues. Despite having low average energy densities, large gelatinous cephalopods are important prey for lancetfish in deep habitats, with energetic values that are comparable to smaller, more muscular cephalopods (95.3 ± 125.8 kJ and 120.2 ± 169.4 kJ, respectively). Holistic consideration of cephalopod beaks in diet analyses will help to elucidate predator foraging behaviors and the trophic and ecological roles of gelatinous cephalopods in deep pelagic food webs.
Keywords	Alepisaurus brevirostris ; Cranchiidae ; Ommastrephidae ; beak ; diet ; energy ; marine fish ; ontogeny ; stomach ; Pacific Ocean
Language	English
Dates of publication	2022-12
Size	p. 155.
Publishing place	Springer Berlin Heidelberg
Document type	Article ; Online
ZDB-ID	1117-4
ISSN	1432-1793 ; 0025-3162
ISSN (online)	1432-1793
ISSN	0025-3162
DOI	10.1007/s00227-022-04116-w
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Harnessing a mesopelagic predator as a biological sampler reveals taxonomic and vertical resource partitioning among three poorly known deep-sea fishes.

Portner, Elan J / Mowatt-Larssen, Tor / Carretero, Alejandro Cano-Lasso / Contreras, Emily A / Woodworth-Jefcoats, Phoebe A / Frable, Benjamin W / Choy, C Anela

Scientific reports

2023 Volume 13, Issue 1, Page(s) 16078

Abstract: Pelagic predators are effective biological samplers of midtrophic taxa and are especially useful in deep-sea habitats where relatively mobile taxa frequently avoid observation with conventional methods. We examined specimens sampled from the stomachs of ... ...

Abstract	Pelagic predators are effective biological samplers of midtrophic taxa and are especially useful in deep-sea habitats where relatively mobile taxa frequently avoid observation with conventional methods. We examined specimens sampled from the stomachs of longnose lancetfish, Alepisaurus ferox, to describe the diets and foraging behaviors of three common, but poorly known deep-sea fishes: the hammerjaw (Omosudis lowii, n = 79, 0.3-92 g), juvenile common fangtooth (Anoplogaster cornuta, n = 91, 0.6-22 g), and juvenile Al. ferox (n = 138, 0.3-744 g). Diet overlap among the three species was high, with five shared prey families accounting for 63 ± 11% of the total prey mass per species. However, distinct differences in foraging strategies and prey sizes were evident. Resource partitioning was greatest between An. cornuta that specialized on small (mean = 0.13 ± 0.11 g), shallow-living hyperiid amphipods and O. lowii that specialized on large (mean = 0.97 ± 0.45 g), deep-dwelling hatchetfishes. Juvenile Al. ferox foraged on a high diversity of prey from both shallow and deep habitats. We describe the foraging ecologies of three midtrophic fish competitors and demonstrate the potential for biological samplers to improve our understanding of deep-sea food webs.
MeSH term(s)	Humans ; Animals ; Ecology ; Ecosystem ; Food Chain ; Fishes ; Diet ; Predatory Behavior
Language	English
Publishing date	2023-09-26
Publishing country	England
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-023-41298-9
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Decline and recovery of pelagic acoustic backscatter following El Niño events in the Gulf of California, Mexico

Portner, Elan J. / Benoit-Bird, Kelly J. / Hazen, Elliott L. / Waluk, Chad M. / Robinson, Carlos J. / Gómez-Gutiérrez, Jaime / Gilly, William F.

Elsevier Ltd Progress in Oceanography. 2022 Aug., v. 206 p.102823-

2022

Abstract: Climatic variability exerts enormous pressures on the structure and function of open ocean ecosystems. Although the responses of primary producers and top predators to these pressures are being increasingly well-documented, little is known about how ... ...

Abstract	Climatic variability exerts enormous pressures on the structure and function of open ocean ecosystems. Although the responses of primary producers and top predators to these pressures are being increasingly well-documented, little is known about how midtrophic communities respond to oceanographic and climatic variability. We address this knowledge gap through a study of the effects of El Niño Southern Oscillation (ENSO) and local environmental conditions on acoustic proxies of the midtrophic community in the Gulf of California, Mexico. We quantified the intensity and distribution of nighttime acoustic backscatter (120 kHz) in the upper 200 m of the water column during 10 oceanographic cruises (2007–2017) and described its response to environmental variability using generalized additive models. ENSO conditions were the strongest drivers of variability in backscatter after accounting for seasonal increases in backscatter with sea surface temperature and chlorophyll-a concentration. Acoustic backscatter in the central Gulf of California decreased significantly during the positive phase of ENSO. Following El Niño events in 2009–10 and 2015–16, mean backscatter declined by an order of magnitude and remained depressed for more than two years before recovering to pre-El Niño levels. Scattering layer density increased with total backscatter, likely an influential factor determining prey availability for pelagic predators. Our findings demonstrate large and sustained impacts of El Niño on the midtrophic community in the Gulf of California and further highlight the need to better understand the responses of midtrophic communities to environmental variability.
Keywords	El Nino ; acoustics ; chlorophyll ; decline ; oceanography ; surface water temperature ; Gulf of California ; Mexico ; Hydroacoustic ; Backscattering layers ; Midtrophic communities ; Generalized additive models ; El Niño Southern Oscillation
Language	English
Dates of publication	2022-08
Publishing place	Elsevier Ltd
Document type	Article ; Online
ISSN	0079-6611
DOI	10.1016/j.pocean.2022.102823
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: The Pelagic Species Trait Database, an open data resource to support trait-based ocean research.

Gleiber, Miram R / Hardy, Natasha A / Roote, Zachary / Krug-MacLeod, Alana M / Morganson, Caitlin J / Tandy, Zackary / George, Iris / Matuch, Cindy / Brookson, Cole B / Daly, Elizabeth A / Portner, Elan J / Choy, C Anela / Crowder, Larry B / Green, Stephanie J

Scientific data

2024 Volume 11, Issue 1, Page(s) 2

Abstract: Trait-based frameworks are increasingly used for predicting how ecological communities respond to ongoing global change. As species range shifts result in novel encounters between predators and prey, identifying prey 'guilds', based on a suite of shared ... ...

Abstract	Trait-based frameworks are increasingly used for predicting how ecological communities respond to ongoing global change. As species range shifts result in novel encounters between predators and prey, identifying prey 'guilds', based on a suite of shared traits, can distill complex species interactions, and aid in predicting food web dynamics. To support advances in trait-based research in open-ocean systems, we present the Pelagic Species Trait Database, an extensive resource documenting functional traits of 529 pelagic fish and invertebrate species in a single, open-source repository. We synthesized literature sources and online resources, conducted morphometric analysis of species images, as well as laboratory analyses of trawl-captured specimens to collate traits describing 1) habitat use and behavior, 2) morphology, 3) nutritional quality, and 4) population status information. Species in the dataset primarily inhabit the California Current system and broader NE Pacific Ocean, but also includes pelagic species known to be consumed by top ocean predators from other ocean basins. The aim of this dataset is to enhance the use of trait-based approaches in marine ecosystems and for predator populations worldwide.
MeSH term(s)	Animals ; Ecosystem ; Fishes ; Food Chain ; Marine Biology ; Pacific Ocean
Language	English
Publishing date	2024-01-12
Publishing country	England
Document type	Dataset ; Journal Article
ZDB-ID	2775191-0
ISSN	2052-4463 ; 2052-4463
ISSN (online)	2052-4463
ISSN	2052-4463
DOI	10.1038/s41597-023-02689-9
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Same-sex sexual behaviour in an oceanic ommastrephid squid, Dosidicus gigas (Humboldt squid)

Hoving, Henk-Jan T. / Fernández-Álvarez, Fernando Á. / Portner, Elan J. / Gilly, William F.

2019

Abstract: Dosidicus gigas (the Humboldt squid) is a widely distributed and ecologically important predator in the eastern Pacific Ocean, but its mating behaviour is poorly understood. Individuals of this species have undergone a drastic change in size at maturity ... ...

Abstract	Dosidicus gigas (the Humboldt squid) is a widely distributed and ecologically important predator in the eastern Pacific Ocean, but its mating behaviour is poorly understood. Individuals of this species have undergone a drastic change in size at maturity in the last years. We investigated mating activity of Humboldt squid in the Gulf of California in 2013, 2014, and 2015 by quantifying spermatangia deposited in the tissue of the buccal area. In 2015, we encountered the smallest mean mantle length of mature specimens recorded to date in the Gulf of California. In all years, numerous males were encountered that had been mated by other males. Spermatangia in males were deposited on the tissue in similar numbers and in the same location as normally occurs in females (the buccal area), suggesting that male-to-male mating behaviour is similar to male-to-female. This behaviour is referred to as same-sex sexual behaviour and has been described for various taxa, including other cephalopods. Overall similarity in mating frequency between males and females and in body size of mated individuals (in 2015) suggests non-discriminative and brief encounters with body size being a cue for mating. This mating strategy may be beneficial for males, as Humboldt squid live in groups where competition for mates is likely high. The energetic costs of male-to-male mating events may be counterbalanced by the fitness profits of indiscriminate mating behaviour.
Subject code	590
Language	English
Publishing date	2019-03-01
Publisher	Springer
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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