Developing a high taxonomic resolution food web model to assess the functional role of forage fish in the California Current ecosystem

Koehn, Laura E.; Essington, Timothy E.; Marshall, Kristin N.; Kaplan, Isaac C.; Sydeman, William J.; Szoboszlai, Amber I.; Thayer, Julie A.

doi:10.1016/j.ecolmodel.2016.05.010

Cited by 58 publications

(66 citation statements)

References 43 publications

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“…Two key forage stocks, Pacific sardine Sardinops sagax and northern anchovy Engraulis mordax (henceforth sardine and anchovy), are important prey sources for harvested species such as salmon Oncorhynchus spp. and albacore tuna Thunnus alalunga, protected species such as humpback whale Megaptera novaeangliae, and numerous species of protected seabirds (Szoboszlai et al 2015, Koehn et al 2016. Sardine and anchovy have fluctuated strongly in abundance over the past 500− 1700 yr (Baumgartner et al 1992, McClatchie et al 2017, and recently both species have declined to less than 10% of contemporary peak abundances (Hill et al 2015, Thayer et al 2017.…”

Section: Introductionmentioning

confidence: 99%

A multi-model approach to understanding the role of Pacific sardine in the California Current food web

Kaplan¹,

Francis²,

Punt³

et al. 2019

Mar. Ecol. Prog. Ser.

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We develop a multi-model approach to explore how abundance of a forage fish (Pacific sardine Sardinops sagax) impacts the ecosystem and predators in the California Current, a region where sardine and anchovy Engraulis mordax have recently declined to less than 10% of contemporary peak abundances. We developed or improved applications of 3 ecosystem modeling approaches: Ecopath, Model of Intermediate Complexity for Ecosystem assessment (MICE), and Atlantis. We also used Ecopath diets to predict impacts to predators using a statistical generalization of the dynamic Ecosim model (Predator Response to the Exploitation of Prey [PREP]). Models that included brown pelican Pelecanus occidentalis at the species level (MICE and Ecopath/PREP) both predict moderate to high vulnerability of brown pelicans to low sardine abundance. This vulnerability arises because sardine comprises a large fraction of their diet, and because other important prey (anchovy) also exhibit large population fluctuations. Two of the ecosystem models (MICE and Atlantis) suggest that California sea lions Zalophus californianus exhibit relatively minor responses to sardine depletion, due to having broader diets and lower reliance on another fluctuating species, anchovy. On the other hand, Ecopath/PREP suggests that sardine declines will have a stronger impact on California sea lions. This discrepancy may in part reflect structural differences in the models: Atlantis and MICE explicitly represent density dependence and age-structure, which can mitigate effects of prey depletion in these models. Future work should identify fisheries management strategies that are robust to uncertainties within and among models, rather than relying on single models to assess ecosystem impacts of management and forage fish abundance. KEY WORDS: Forage fish • Pacific sardine • California Current • Ecosystem model • California sea lion • Brown pelican • Multi-model approach Contribution to the Theme Section 'Drivers of dynamics of small pelagic fish resources: biology, management and human factors'

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Section: Introductionmentioning

confidence: 99%

A multi-model approach to understanding the role of Pacific sardine in the California Current food web

Kaplan¹,

Francis²,

Punt³

et al. 2019

Mar. Ecol. Prog. Ser.

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“…Where objectives have been identified, scenarios can be designed to generate outputs that are linked to these objectives so that the multi-objective performance of alternative management actions can be compared (e.g., Fulton et al, 2014;Punt et al, 2016a). Ecopath, a highly-resolved, forage fish-centric version of a food-web model used to identify highly dependent sardine predators (Koehn et al, 2016); MICE, a model of intermediate complexity for ecosystem assessment built to evaluate the impacts of sardine harvest on predators (Punt et al, 2016b); Atlantis, an end-to-end ecosystem model of the California Current Ecosystem (Kaplan et al, 2017). DOI: https://doi.org/10.1525/elementa.338.f1…”

Section: Knowledge Is Applicablementioning

confidence: 99%

“…To complement the MICE, we applied a multi-model approach (Kaplan et al, 2018) to evaluate the broader ecosystem-level impacts of the range of sardine abundances projected by the MICE under the current control rule ( Table 1). This multi-model approach (Figure 2) involved application of a simple food web model (Koehn et al, 2016) as well as a full ecosystem Atlantis model (Kaplan et al, 2017). The food web model allowed calculation of indicators of prey importance in the food web and predator dependence upon those prey groups.…”

Section: Illustrationmentioning

confidence: 99%

“…This model included the influence of an environmental variable, temperature, on recruitment. The next most complicated model was the static food web model constructed specifically for California Current forage fish with high trophic resolution (Koehn et al, 2016). This model was used to identify predators most likely to be highly dependent upon sardines and therefore potentially impacted by sardine harvest, and to identify forage species in addition to sardine that are important prey in the California Current.…”

Section: Illustrationmentioning

confidence: 99%

“…In the OMF Pacific sardine working group, diets of predators in two models, the MICE (Punt et al, 2016b) and the Atlantis ecosystem model (Kaplan et al, 2017), were informed by the highly resolved Ecopath food web model of the California Current ecosystem (Koehn et al, 2016). Data collection and initial model parameterization for the Atlantis model and the food web model were a collaborative effort (with authors shared across papers).…”

Section: Illustrationmentioning

confidence: 99%

See 2 more Smart Citations

Linking knowledge to action in ocean ecosystem management: The Ocean Modeling Forum

Francis

Levin

Punt

et al. 2018

Elementa: Science of the Anthropocene

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The sustainable use of global marine resources depends upon science-based decision processes and systems. Informing decisions with science is challenging for many reasons, including the nature of science and science-based institutions. The complexity of ecosystem-based management often requires the use of models, and model-based advice can be especially difficult to convert into policies or decisions. Here, we suggest five characteristics of model-based information and advice for successfully informing ocean management decision-making, based on the Ocean Modeling Forum framework. Illustrated by examples from two fisheries case studies, Pacific sardines Sardinops sagax and Pacific herring Clupea pallasii, we argue that actionable model-based output should be aspirational, applicable, parsimonious, co-produced, and amplifying.

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A structured seabird population model reveals how alternative forage fish control rules benefit seabirds and fisheries

Koehn

Siple

Essington

2021

Ecological Applications

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Fisheries for forage fish may affect the survival and reproduction of piscivorous predators, especially seabirds. However, seabirds have evolved life history strategies to cope with natural fluctuations in prey and it is difficult to separate effects of fishing on seabirds from impacts of natural variability. To date, potential impacts of forage fisheries on seabirds have mainly been explored using ecosystem models that simplify seabird–forage‐fish dynamics. We sought to explore how different forage fish harvest policies affect seabirds, accounting for structured population dynamics, life history specifics, and variation in forage fish dependencies across life stages; and how impacts vary across seabird and forage fish life histories. To explore these impacts, we developed an age‐stage structured seabird model that incorporates seabird diet specialization, foraging behavior, and reproductive strategy, as well as different functional responses between prey availability and adult survival, juvenile survival, reproductive success, and breeder propensity. We parameterized this model for two contrasting seabird life histories: (1) a low fecundity, limited foraging range, diet specialist (“restricted”); and (2) a high fecundity, wide ranging, diet generalist (“flexible”). Each was paired with two different forage fish prey archetypes that were fished under various control rules. The restricted seabird population was expectedly less robust to constant fishing pressure than the flexible seabird, and this sensitivity was mainly due to functional response parameterization, rather than other life history parameters. Particularly, the restricted seabird was highly sensitive to the relationship between prey availability and adult survival but was not sensitive to the relationship between prey and reproductive success. An adaptive biomass‐limit harvest rule for forage fish resulted in substantially higher seabird abundance compared to constant fishing across all scenarios, with minimal trade‐offs to the fishery (depending on fishery management objectives). However, mechanisms governing the impact of the forage fish fishery on the seabird varied by forage fish type. Therefore, tailoring forage fish management strategies to forage fish life history can lead to mutually acceptable outcomes for fisheries and seabirds. If data or time are limited, an adaptive control rule is likely a safe bet for meeting seabird conservation objectives with limited impacts to fisheries.

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Developing a high taxonomic resolution food web model to assess the functional role of forage fish in the California Current ecosystem

Cited by 58 publications

References 43 publications

A multi-model approach to understanding the role of Pacific sardine in the California Current food web

A multi-model approach to understanding the role of Pacific sardine in the California Current food web

Linking knowledge to action in ocean ecosystem management: The Ocean Modeling Forum

A structured seabird population model reveals how alternative forage fish control rules benefit seabirds and fisheries

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