Monk Seal Ecosystem Model Data: A Comparison of Ecosystem Structure and Energy Flows of Monk Seal Populations from Laysan Island and French Frigate Shoals in the Northwestern Hawaiian Islands from 1998 through 2015 (NCEI Accession 0190881)
To understand various ecosystem dynamics that could explain observed changes and differences in monk seal biomass at French Frigate Shoals (FFS) and Laysan (LAY), Ecopath with Ecosim (EwE) version 6.4.4 modeling software was used to conduct two types of simulations, sensitivity (to understand the system) and hindcast (to evaluate drivers of monk seal population dynamics). EwE models for LAY and FFS were developed and model output was compared between the 2 models. The model output data included in the data sets represent the most important conclusions as reported in the publication from this study. These are (1) the mean of the last 5 years of each perturbation for sensitivity assessment; and (2) hindcast simulations. The first data set was used to understand the main drivers of the trophic structure and energy flow in the ecosystems. Four perturbation scenarios were simulated for a time span of 40 years (2010 through 2049): (a) baseline (compare static structural ecosystem composition between FFS and LAY), (b) altered predator abundance (30% decrease in biomass of main predators in the ecosystem), (c) altered monk seal prey abundance (30% decrease in biomass of main monk seal prey groups, with and without bottomfish to test how much bottomfish accounts for changes, and (d) altered primary productivity (change productivity annually by 10% for both phytoplankton and benthic algae through an annual forcing factor of 0.9 and 1.1 on both groups). The hindcast simulations were performed to evaluate the importance of historical stressors to monk seal population dynamics by selecting the best-fit model for the monk seal biomass time series (1998-2015). Stressors included were (a) fishing with time series based on commercial fishery data, (b) environment with time series of the monthly PDO index as a multiplier for primary productivity, (c) additional mortality simulated with a constant removal of monk seals of varied intensities, and (4) combinations of these 3 stressors (2a and 2c being the most important with regard to the observed trend in monk seal population). Time series observation data of monk seal biomass and benthic bottomfish biomass, as well as catch time series of bank sharks (only for FFS), benthic and demersal bottomfish, bank jacks, and macroheterotrophs (lobsters) were loaded into Ecosim for model fitting. Refer to Weijerman et al (2017) for complete details.
Dataset Citation
- Cite as: Weijerman, Mariska; Robinson, Stacie; Parrish, Frank; Polovina, Jeffrey; Littnan, Charles; Pacific Islands Fisheries Science Center (2019). Monk Seal Ecosystem Model Data: A Comparison of Ecosystem Structure and Energy Flows of Monk Seal Populations from Laysan Island and French Frigate Shoals in the Northwestern Hawaiian Islands from 1998 through 2015 (NCEI Accession 0190881). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://www.ncei.noaa.gov/archive/accession/0190881. Accessed [date].
Dataset Identifiers
ISO 19115-2 Metadata
gov.noaa.nodc:0190881
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NOAA National Centers for Environmental Information +1-301-713-3277 NCEI.Info@noaa.gov |
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NOAA National Centers for Environmental Information ncei.info@noaa.gov |
Time Period | 1998-01-01 to 2015-12-31 |
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West: -172
East: -166
South: 23.5
North: 26
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Dataset Progress Status | Complete - production of the data has been completed Historical archive - data has been stored in an offline storage facility |
Data Update Frequency | As needed |
Supplemental Information | 9 model data outputs and 2 data dictionaries are provided in this archival package. Submission Package ID: KHJDLU |
Purpose | The main objective of this study was to understand the difference in ecosystem dynamics that could explain the observed decrease in monk seal biomass at French Frigate Shoals and the more stable biomass at Laysan. Specifically we investigated the relative influence of potential drivers---including primary productivity, prey population, and predation---on the monk seal populations in 40-year simulations and the external drivers of climate and fishing with an additional mortality on monk seals in hindcast simulations. Understanding the drivers and predictability of population trends will illuminate areas of focus for Hawaiian monk seal recovery efforts. |
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Last Modified: 2023-02-06T13:35:25Z
For questions about the information on this page, please email: ncei.info@noaa.gov
For questions about the information on this page, please email: ncei.info@noaa.gov