Environmental conditions and prey-switching by a seabird predator impact juvenile salmon survival

Wells, Brian K.; Santora, Jarrod A.; Henderson, Mark J.; Warzybok, Peter M.; Jahncke, Jaime; Bradley, Russell W.; Huff, David D.; Schroeder, Isaac D.; Nelson, Peter A.; Field, John C.; Ainley, David G.

doi:10.1016/j.jmarsys.2017.05.008

Cited by 71 publications

(114 citation statements)

References 58 publications

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“…This alternating pattern reflects the pulse of biodiversity of epipelagic fish guilds and has consequences for trophodynamics in this ecosystem. During cooler periods, the high biodiversity of YOY groundfish is related to their combined high abundance and reflects a typical upwelling food web in the CCE, where these species represent key conduits of energy transfer to upperlevel predators , Wells et al 2017. The increased diversity of coastal mesopelagic forage species into the ecosystem during warm years results in overall higher biodiversity anomalies but is not strictly correlated with abundance -high diversity is generally observed during warmer, lower productivity years, such as El Niño years.…”

Section: Discussionmentioning

confidence: 99%

“…1) feed primarily on YOY rockfish when they are abundant and switch to target northern anchovy when YOY rockfish are unavailable (Ainley & Boekelheide 1990, Sydeman et al 2001. When YOY rockfish are less available, breeding success tends to be lower, although the most severe declines occur during periods of unusual environmental conditions (such as El Niño events) that correspond with both very low YOY rockfish abundance and low productivity throughout the ecosystem more generally (Field et al 2010, Wells et al 2017. Similarly, humpback whales Megaptera novaeangliae may alter their foraging behavior between krill and northern anchovy as a function of climate-driven ocean conditions that determine which prey type is abundant, such that krill are preyed on more frequently in cool, high upwelling years and northern anchovy in years of lower productivity and warmer SST (Fleming et al 2016).…”

Section: Trophic Considerations Of Epipelagic Fish Biodiversitymentioning

confidence: 99%

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Impacts of ocean climate variability on biodiversity of pelagic forage species in an upwelling ecosystem

Santora¹,

Hazen²,

Schroeder³

et al. 2017

Mar. Ecol. Prog. Ser.

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Monitoring essential marine biodiversity variables is an effective means for assessing impacts of climate change and human-related stressors such as pollution, overfishing and habitat destruction. Yet little is known about the natural variability of biodiversity in pelagic upwelling marine ecosystems, which are often subject to substantial interannual and decadal variability of ocean climate conditions. Using data from a pelagic midwater trawl survey, we quantified diversity indices of epipelagic forage species collected over 26 yr (1990 to 2015) to determine the natural variability and environmental determinants of biodiversity within the California Current upwelling ecosystem. Biodiversity time series indicate there are 2 alternate forage species assemblages that relate to differences in cool/strong and warm/weak upwelling years that vary in 3 to 5 yr cycles. Cooler years are associated with increased biodiversity of juvenile groundfish, whereas warm years coincide with increased biodiversity of coastal and mesopelagic fishes and species originating from southern and subtropical waters. During 2015, a year of anomalous warm surface ocean conditions, we observed unprecedented high levels of biodiversity and attribute it to high abundance of juvenile groundfish combined with an unusually high transport of subtropical and offshore species into neritic waters. Using a combination of remote sensing and in situ hydrographic data, we compare 2015 to previous anomalous ocean climate conditions and discuss how biodiversity of forage species may impact trophodynamics of upwelling ecosystems and predator−prey interactions. Attributing changes in marine biodiversity to productivity cycles and anomalous climate events, and detecting long-term biodiversity trends, provides a critical index toward understanding climate forcing on upwelling ecosystems.

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Section: Discussionmentioning

confidence: 99%

Section: Trophic Considerations Of Epipelagic Fish Biodiversitymentioning

confidence: 99%

Impacts of ocean climate variability on biodiversity of pelagic forage species in an upwelling ecosystem

Santora¹,

Hazen²,

Schroeder³

et al. 2017

Mar. Ecol. Prog. Ser.

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“…We used cohort reconstruction to estimate early survival of Chinook salmon using recoveries of hatchery fish implanted with coded‐wire tags and released between 1988 and 2010 (Wells et al., ). Cohort reconstruction is a backward projection method that estimates numbers of fish that were available for capture based on the number captured and natural mortality (Magnusson & Hilborn, ).…”

Section: Methodsmentioning

confidence: 99%

Spatial variability in ocean‐mediated growth potential is linked to Chinook salmon survival

Henderson

Fiechter

Huff

et al. 2018

Fisheries Oceanography

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Early ocean survival of Chinook salmon, Oncorhynchus tshawytscha, varies greatly inter‐annually and may be the period during which later spawning abundance and fishery recruitment are set. Therefore, identifying environmental drivers related to early survival may inform better models for management and sustainability of salmon in a variable environment. With this in mind, our main objectives were to (a) identify regions of high temporal variability in growth potential over a 23‐year time series, (b) determine whether the spatial distribution of growth potential was correlated with observed oceanographic conditions, and (c) determine whether these spatial patterns in growth potential could be used to estimate juvenile salmon survival. We applied this method to the fall run of the Central Valley Chinook salmon population, focusing on the spring and summer period after emigration into central California coastal waters. For the period from 1988 to 2010, juvenile salmon growth potential on the central California continental shelf was described by three spatial patterns. These three patterns were most correlated with upwelling, detrended sea level anomalies, and the strength of onshore/offshore currents, respectively. Using the annual strength of these three patterns, as well as the overall growth potential throughout central California coastal waters, in a generalized linear model we explained 82% of the variation in juvenile salmon survival estimates. We attributed the relationship between growth potential and survival to variability in environmental conditions experienced by juvenile salmon during their first year at sea, as well as potential shifts in predation pressure following out‐migration into coastal waters.

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“…Over these time scales, upwelling in the California Current ecosystem has been shown to have significant effects on a range of ecological processes including production in fisheries (Ware & Thomson, 2005), zooplankton and fish community composition (Brodeur et al, 2008;Keister & Peterson, 2003) and diversity (Santora, Hazen, et al, 2017), ©2019. predator diet composition (Wells et al, 2017), animal growth rates (Fisher & Pearcy, 1988), life history strategies (Peterson, 1998), and carbon cycling (Barth et al, 2007). This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.…”

Section: Introductionmentioning

confidence: 99%

Forage Species Swarm in Response to Coastal Upwelling

Benoit‐Bird

Waluk

Ryan

2019

Geophysical Research Letters

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We observed the distribution and identity of forage species to infer behavioral changes in response to intraseasonal variation in the coastal upwelling ecosystem of Monterey Bay, California. While the biomass of forage species remained comparable, the small‐scale distribution of krill and anchovies was strongly affected by upwelling conditions. When regional upwelling influences were strong in the Bay, both species formed numerous discrete swarms and schools. During relaxation, both species were more diffusely distributed. Rather than gross changes in spatial distribution, a process that could take a long time for these relatively small animals, forage species responded to the short time scale dynamics that occur between days in the upwelling season with changes in their aggregative behavior. The behavioral responses observed highlight the need to study within‐season dynamics in upwelling systems in addition to their cumulative influence in order to understand the ecological processes of these productive systems.

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Environmental conditions and prey-switching by a seabird predator impact juvenile salmon survival

Cited by 71 publications

References 58 publications

Impacts of ocean climate variability on biodiversity of pelagic forage species in an upwelling ecosystem

Impacts of ocean climate variability on biodiversity of pelagic forage species in an upwelling ecosystem

Spatial variability in ocean‐mediated growth potential is linked to Chinook salmon survival

Forage Species Swarm in Response to Coastal Upwelling

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