EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data
Mass-balance ecosystem models including Ecopath with Ecosim (EwE) are widely used tools for analyzing aquatic ecosystems to support strategic ecosystem-based management. These models are typically developed by first tuning unknown parameters to achieve mass balance (termed “Ecopath”), then projectin...
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2024
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crescholarship:10.32942/x2qk81 2024-09-15T17:35:35+00:00 EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data Thorson, James Kristensen, Kasper Aydin, Kerim Gaichas, Sarah Kimmel, David McHuron, Elizabeth Nielsen, Jens Townsend, Howard Whitehouse, Andy 2024 http://dx.doi.org/10.32942/x2qk81 unknown California Digital Library (CDL) posted-content 2024 crescholarship https://doi.org/10.32942/x2qk81 2024-08-01T04:24:15Z Mass-balance ecosystem models including Ecopath with Ecosim (EwE) are widely used tools for analyzing aquatic ecosystems to support strategic ecosystem-based management. These models are typically developed by first tuning unknown parameters to achieve mass balance (termed “Ecopath”), then projecting dynamics over time (“Ecosim”) while sometimes tuning predator-prey vulnerability parameters to optimize fit to available time-series. By contrast, population-dynamics (stock assessment) and multi-species models typically estimate a wide range of biological rates and parameters via their fit to time-series data, assess uncertainty via a statistical likelihood, and increasingly include process errors as “state-space models” to account for nonstationary dynamics and unmodeled ecosystem variables. Here, we introduce a state-space model “EcoState” (and associated R-package) that estimates parameters representing mass-balance dynamics directly via their fit to time-series data (absolute or relative abundance indices and fisheries catches) while also estimating the magnitude of process errors using RTMB. A case-study demonstration focused on Alaska pollock (Gadus chalcogrammus) in the eastern Bering Sea suggests that fluctuations in krill consumption are associated with cycles of increased and decreased pollock production. A self-test simulation experiment confirms that estimating process errors can improve estimates of productivity (growth and mortality) rates. Overall, we show that state-space mass-balance models can be fitted to time-series data (similar to surplus production stock assessment models), and can attribute time-varying productivity to both bottom-up and top-down drivers including the contribution of individual predator and prey interactions. Other/Unknown Material alaska pollock Bering Sea Alaska eScholarship Repository (University of California) |
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Mass-balance ecosystem models including Ecopath with Ecosim (EwE) are widely used tools for analyzing aquatic ecosystems to support strategic ecosystem-based management. These models are typically developed by first tuning unknown parameters to achieve mass balance (termed “Ecopath”), then projecting dynamics over time (“Ecosim”) while sometimes tuning predator-prey vulnerability parameters to optimize fit to available time-series. By contrast, population-dynamics (stock assessment) and multi-species models typically estimate a wide range of biological rates and parameters via their fit to time-series data, assess uncertainty via a statistical likelihood, and increasingly include process errors as “state-space models” to account for nonstationary dynamics and unmodeled ecosystem variables. Here, we introduce a state-space model “EcoState” (and associated R-package) that estimates parameters representing mass-balance dynamics directly via their fit to time-series data (absolute or relative abundance indices and fisheries catches) while also estimating the magnitude of process errors using RTMB. A case-study demonstration focused on Alaska pollock (Gadus chalcogrammus) in the eastern Bering Sea suggests that fluctuations in krill consumption are associated with cycles of increased and decreased pollock production. A self-test simulation experiment confirms that estimating process errors can improve estimates of productivity (growth and mortality) rates. Overall, we show that state-space mass-balance models can be fitted to time-series data (similar to surplus production stock assessment models), and can attribute time-varying productivity to both bottom-up and top-down drivers including the contribution of individual predator and prey interactions. |
format |
Other/Unknown Material |
author |
Thorson, James Kristensen, Kasper Aydin, Kerim Gaichas, Sarah Kimmel, David McHuron, Elizabeth Nielsen, Jens Townsend, Howard Whitehouse, Andy |
spellingShingle |
Thorson, James Kristensen, Kasper Aydin, Kerim Gaichas, Sarah Kimmel, David McHuron, Elizabeth Nielsen, Jens Townsend, Howard Whitehouse, Andy EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data |
author_facet |
Thorson, James Kristensen, Kasper Aydin, Kerim Gaichas, Sarah Kimmel, David McHuron, Elizabeth Nielsen, Jens Townsend, Howard Whitehouse, Andy |
author_sort |
Thorson, James |
title |
EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data |
title_short |
EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data |
title_full |
EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data |
title_fullStr |
EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data |
title_full_unstemmed |
EcoState: Extending Ecopath with Ecosim to estimate biological parameters and process errors using RTMB and time-series data |
title_sort |
ecostate: extending ecopath with ecosim to estimate biological parameters and process errors using rtmb and time-series data |
publisher |
California Digital Library (CDL) |
publishDate |
2024 |
url |
http://dx.doi.org/10.32942/x2qk81 |
genre |
alaska pollock Bering Sea Alaska |
genre_facet |
alaska pollock Bering Sea Alaska |
op_doi |
https://doi.org/10.32942/x2qk81 |
_version_ |
1810468239654780928 |