Heatwave‐induced synchrony within forage fish portfolio disrupts energy flow to top pelagic predators

Global Change Biology, Journal Year: 2021, Volume and Issue: 27(9), P. 1859 - 1878

Published: Feb. 14, 2021

Abstract During the Pacific marine heatwave of 2014–2016, abundance and quality several key forage fish species in Gulf Alaska were simultaneously reduced throughout system. Capelin ( Mallotus catervarius ), sand lance Ammodytes personatus herring Clupea pallasii ) populations at historically low levels, within this community abrupt declines portfolio effects identify trophic instability onset heatwave. Although compensatory changes age structure, size, growth or energy content observed to varying degrees among all these fish, none able fully mitigate adverse impacts heatwave, which likely included both top‐down bottom‐up forcing. Notably, demographic structure suggested size‐selective removals typical regulation. At same time, zooplankton communities may have driven regulation as copepod shifted toward smaller, warm water species, euphausiid biomass was owing loss cold‐water species. Mediated by on community, an unprecedented disruption normal pelagic food web signaled higher level disruptions during 2015–2016, when seabirds, mammals, groundfish experienced shifts distribution, mass mortalities, reproductive failures. Unlike decadal‐scale variability underlying ecosystem regime shifts, appeared temporarily overwhelm ability buffer against imposed anomalies, thereby eliminating any ecological advantages that accrued from having a suite coexisting with differing life‐history compensations.

Language: Английский

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Flying Fish Habitat and Co‐Occurrence With Seabirds in the Northern Gulf of Mexico

Fisheries Oceanography, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 23, 2025

ABSTRACT Flying fish (family Exocoetidae ) play an important role in marine food webs, linking sub‐surface and aerial predators. The association of seabirds with predators subtropical tropical regions through facilitated foraging events is a well‐known phenomenon sometimes used to identify fishing grounds for flying fish, roe, tunas. In the northern Gulf Mexico (nGoM), few studies have assessed distribution, none directly evaluated fish–seabird co‐occurrence. Using vessel‐based observations surfacing flights, we characterized distribution their co‐occurrence patterns nGoM. We modeled relative density flights using Generalized Additive Models. then all seabird species seen area, encompassing footprint detections. were detected across U.S. Exclusive Economic Zone, flight densities greater on mid‐continental shelf into pelagic waters south Louisiana, associated regionally low chlorophyll‐ warm water. greatest spring months early fall months. Sooty terns ( Onychoprion fuscatus ), considered near‐obligate commensals tuna, contributed much higher percent cumulative co‐occurring versus without fish. could be ecological attractant high abundances visually conspicuous sooty terns, presence which may lead formation ephemeral consisting mixed‐species flocks.

Language: Английский

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Shifting fish distributions impact predation intensity in a sub‐Arctic ecosystem

Ecography, Journal Year: 2022, Volume and Issue: 2022(9)

Published: June 23, 2022

An abundance of studies in marine systems have documented species range shifts response to climate change, and many more used distribution models project ranges under future conditions. However, there is increasing interest moving beyond a single‐species focus understand how redistribution alters ecosystem dynamics via changes trophic interactions. We employed spatiotemporal characterize decadal‐scale spatial overlap between the juvenile walleye pollock Gadus chalcogrammus distributions four its groundfish predators: arrowtooth flounder Atheresthes stomias , Pacific cod macrocephalus halibut Hippoglossus stenolepis adult pollock. These fishes represent ecologically commercially important rapidly changing sub‐Arctic ecosystem, eastern Bering Sea, Alaska, USA. then examined whether corresponded predation, using predator stomach contents. found marked two predators (arrowtooth halibut) over 34 years, with corresponding increases population‐scale predation pressure. By contrast, we did not find clear relationships for pollock, which constitute much smaller diet proportion. Our findings highlight complexity predicting generalist suggest need better process‐based methods understanding potential ecological impacts coupled shifts. simple metrics relatively specialized their prey offer promise as means integrate predictions from into ecosystem‐based fisheries management.

Language: Английский

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Evaluating ecosystem caps on fishery yield in the context of climate stress and predation

Ecological Applications, Journal Year: 2025, Volume and Issue: 35(3)

Published: April 1, 2025

Abstract Ecosystem‐based fisheries management strives to account for species interactions and ecosystem processes in natural resource conservation. In this context, ecosystem‐wide caps on total fishery catches have been proposed as one tool manage multispecies with an approach. However, determining effective is complicated because fish stock production influenced by environmental conditions, interactions, fishing. Consequently, the implementation of frameworks remains uncommon. We investigated whether should climate variability predator–prey dynamics achieve objectives complex marine ecosystems. considered example Gulf Alaska (United States), a North Pacific large where annual groundfish are managed using “optimum yield” cap 800,000 t. simulated yield 12 most abundant commercially valuable stocks under selected fishing scenarios end‐to‐end model (Atlantis), which accounts dynamics. found that was never projected exceed mt optimum across mortalities. Projected change led decreased yield, predation from underexploited predator arrowtooth flounder ( Atheresthes stomias ) foregone catches. Groundfish removals had negative indirect effects predators, despite exceeding cap, highlighting ineffective may not protect non‐target species. These results suggest currently used be too high constrain future low exploitation rates predators. propose reviewed when productivity, or change.

Language: Английский

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Climate‐informed models benefit hindcasting but present challenges when forecasting species–habitat associations

Ecography, Journal Year: 2022, Volume and Issue: 2022(10)

Published: July 20, 2022

Although species distribution models (SDMs) are commonly used to hindcast fine‐scale population metrics, there remains a paucity of information about how well these predict future responses climate. Many conventional SDMs rely on spatially‐explicit but time‐invariant conditions quantify distributions and densities. We compared status quo ‘static' with more climate‐informed 'dynamic' assess whether the addition time‐varying processes would improve performance and/or forecast skill. Here, we present two groundfish case studies from Bering Sea – high latitude system that has recently undergone considerable warming. relied statistics (R 2 , % deviance explained, UBRE or GCV) evaluate for presence–absence, numerical abundance biomass arrowtooth flounder Atheresthes stomias walleye pollock Gadus chalcogrammus . then retrospective skill testing near‐term Retrospective enables direct comparisons between forecasts observations through process fitting forecasting nested submodels within given time series. found inclusion covariates improved hindcasts. However, dynamic either did not decreased relative static SDMs. This is likely result rapidly changing temperatures ecosystem, which required environmental were outside range observed values. Until additional model development allows fully predictions, (or persistence models) may serve as reliable placeholders, especially when anomalous anticipated. Nonetheless, our findings demonstrate support use rather than selecting priori based their ability species–habitat associations in past.

Language: Английский

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Temporal changes in the diet composition and trophic level of walleye pollock (Gadus chalcogrammus) inhabiting the middle-eastern coast of Korea

Marine Environmental Research, Journal Year: 2024, Volume and Issue: 198, P. 106493 - 106493

Published: April 11, 2024

Language: Английский

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An ensemble approach to understand predation mortality for groundfish in the Gulf of Alaska

Fisheries Research, Journal Year: 2022, Volume and Issue: 251, P. 106303 - 106303

Published: March 20, 2022

Language: Английский

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Applying Bayesian model selection to determine ecological covariates for recruitment and natural mortality in stock assessment

ICES Journal of Marine Science, Journal Year: 2021, Volume and Issue: 78(8), P. 2875 - 2894

Published: Aug. 12, 2021

Abstract Incorporating ecological covariates into fishery stock assessments may improve estimates, but most are estimated with error. Model selection criteria often used to identify support for covariates, have some limitations and rely on assumptions that violated. For a more rigorous evaluation of we four popular influencing natural mortality or recruitment in Bayesian assessment Pacific herring (Clupea pallasii) Prince William Sound, Alaska. Within this framework, were incorporated either as fixed effects latent variables (i.e. associated error). We found pink salmon increasing mortality, which was selected by three criteria. There ambiguous other (walleye pollock the North Gyre Oscillation) (hatchery-released juvenile 1989 regime shift). Generally, similar values among suggest no clear evidence consistent effect any covariate. Models sensitive prior specification provide potentially very different results. recommend using multiple exploring statistical about their use assessment.

Language: Английский

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Time-varying predation as a modifier of constant natural mortality for Gulf of Alaska walleye pollock

Fisheries Research, Journal Year: 2022, Volume and Issue: 254, P. 106391 - 106391

Published: June 14, 2022

Although highly variable in time and space, predation remains the greatest source of mortality for juvenile lower trophic-level fishes. As such, can have substantial long-term effects on dynamics these prey. Gulf Alaska walleye pollock (Gadus chalcogrammus) has shown considerable variability biomass over past four decades. During this same time, demersal fish community transitioned from being dominated by to a system comprised primarily upper predators. We estimated time-varying better understand its population currently "top heavy" system. Our index accounted spatiotemporal variation predator biomass, bioenergetics-based rations, age-specific proportions consumed (1990–2019). To evaluate population-level impacts predation, we included an removals as part stock assessment model. This formulation allowed non-annual data inputs proportionality constant with which scale predation. Age-specific natural was vary according penalized random walk. found that ranged 37% higher 17% than mean. Resulting estimates total differed much relative model without mortality, though maximum difference exploitable only 14%. Using empirically-derived modify allows scientists assessed species. approach provides relatively simple way incorporating ecological information into single-species assessments may reduce bias compared conventional models do not account changes mortality. Notably, including help identify inconsistencies warrant further consideration.

Language: Английский

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Black Terns (Chlidonias niger) beyond the breeding grounds: Occurrence, relative density, and habitat associations in the northern Gulf of Mexico

The Wilson Journal of Ornithology, Journal Year: 2024, Volume and Issue: 136(2)

Published: June 26, 2024

Les guifettes noires d'Amérique du Nord (Chlidonias niger) se reproduisent principalement dans la région des Prairies Pothole sud Canada et nord États-Unis, hivernent les eaux centrale Sud migrent souvent à travers le golfe Mexique (nGoM). Cette espèce a montré déclins de population long terme est exposée une myriade menaces anthropiques nGoM, y compris marées noires, avec environ 800 1 000 individus blessés lors marée noire Deepwater Horizon, mais études historiques sur l'utilisation nGoM par sont rares, couverture spatiale temporelle incohérente. À l'aide d'observations basées navires recueillies 2017 2019, nous caractérisons l'occurrence guifette marines nGoM. Nous développâmes deux modèles d'habitat distincts: l'un décrivant aspects spatiaux temporels l'autre densité relative lorsqu'elles présentes. Au cours 10 mois d'enquêtes, janvier octobre, observâmes en sept (de mars mai juillet octobre), plateau continental <200 m profondeur. densités relatives étaient plus élevées automne, coïncidant migration vers sud. distribution suggèrent association embouchures ou ports rivières, ainsi qu'avec fraîches productives, fréquemment associées près l'embouchure fleuve Mississippi juste au large Corpus Christi, Texas. Une meilleure compréhension pourrait éclairer préparation réponse aux futures donner un aperçu interactions potentielles l'installation parcs éoliens offshore l'aquaculture.

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