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Evaluation and management implications of uncertainty in a multispecies size-structured model of population and community responses to fishing.

Thorpe RB, Le Quesne WJ, Luxford F, Collie JS, Jennings S - Methods Ecol Evol (2014)

Bottom Line: This unfiltered ensemble was reduced to 188 plausible models, the filtered ensemble (FE), by screening outputs against fish abundance data and ecological principles such as requiring species' persistence.Effects of parameter uncertainty on estimates of single-species management reference points for fishing mortality (F MSY, fishing mortality rate providing MSY, the maximum sustainable yield) and biomass (B MSY, biomass at MSY) were evaluated by calculating probability distributions of estimated reference points with the FE.There was a 50% probability that multispecies F MSY could be estimated to within ±25% of its actual value, and a 50% probability that B MSY could be estimated to within ±40% of its actual value.Signal-to-noise ratio was assessed for four community indicators when mortality rates were reduced from current rates to F MSY.Further, the power of an ongoing international monitoring survey to detect predicted responses of size spectrum slope was higher than for other size-based metrics.Synthesis and applications: Application of the ensemble model approach allows explicit representation of parameter uncertainty and supports advice and management by (i) providing uncertainty intervals for management reference points, (ii) estimating working values of reference points that achieve a defined reduction in risk of not breaching the true reference point, (iii) estimating the responsiveness of population, community, food web and biodiversity indicators to changes in F, (iv) assessing the performance of indicators and monitoring programmes and (v) identifying priorities for data collection and changes to model structure to reduce uncertainty.

View Article: PubMed Central - PubMed

Affiliation: Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft Laboratory Lowestoft, NR33 0HT, UK.

ABSTRACT

Implementation of an ecosystem approach to fisheries requires advice on trade-offs among fished species and between fisheries yields and biodiversity or food web properties. However, the lack of explicit representation, analysis and consideration of uncertainty in most multispecies models has limited their application in analyses that could support management advice.We assessed the consequences of parameter uncertainty by developing 78 125 multispecies size-structured fish community models, with all combinations of parameters drawn from ranges that spanned parameter values estimated from data and literature. This unfiltered ensemble was reduced to 188 plausible models, the filtered ensemble (FE), by screening outputs against fish abundance data and ecological principles such as requiring species' persistence.Effects of parameter uncertainty on estimates of single-species management reference points for fishing mortality (F MSY, fishing mortality rate providing MSY, the maximum sustainable yield) and biomass (B MSY, biomass at MSY) were evaluated by calculating probability distributions of estimated reference points with the FE. There was a 50% probability that multispecies F MSY could be estimated to within ±25% of its actual value, and a 50% probability that B MSY could be estimated to within ±40% of its actual value.Signal-to-noise ratio was assessed for four community indicators when mortality rates were reduced from current rates to F MSY. The slope of the community size spectrum showed the greatest signal-to-noise ratio, indicating that it would be the most responsive indicator to the change in fishing mortality F. Further, the power of an ongoing international monitoring survey to detect predicted responses of size spectrum slope was higher than for other size-based metrics.Synthesis and applications: Application of the ensemble model approach allows explicit representation of parameter uncertainty and supports advice and management by (i) providing uncertainty intervals for management reference points, (ii) estimating working values of reference points that achieve a defined reduction in risk of not breaching the true reference point, (iii) estimating the responsiveness of population, community, food web and biodiversity indicators to changes in F, (iv) assessing the performance of indicators and monitoring programmes and (v) identifying priorities for data collection and changes to model structure to reduce uncertainty.

No MeSH data available.


(a) Probability of species' collapse as a function of fishing mortality, with probability expressed as the proportion of variants in the filtered ensemble (FE) which result in collapses (B < 10% B0). The lightest grey tone indicates probability for the most sensitive species and successively darker tones the probabilities for two or more (up to 14) species. (b) Relationship between mean total yield from the community and fishing mortality. Grey shading and broken lines denote 50% and 90% uncertainty intervals, respectively.
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fig06: (a) Probability of species' collapse as a function of fishing mortality, with probability expressed as the proportion of variants in the filtered ensemble (FE) which result in collapses (B < 10% B0). The lightest grey tone indicates probability for the most sensitive species and successively darker tones the probabilities for two or more (up to 14) species. (b) Relationship between mean total yield from the community and fishing mortality. Grey shading and broken lines denote 50% and 90% uncertainty intervals, respectively.

Mentions: Total community yield was maximized when F ≈ 1·6 × FMSY (Fig. 6). Fishing mortality had to be reduced to FMSY or below to avoid all possibility of species' collapse. At 3 × FMSY, an approximation of maximum ‘historic’ F for North Sea target species, mean total yield was predicted to be similar to yield at FMSY, or around 85% of the maximum, but two species were expected to collapse, and probability of collapse was >0·1 for another five species. In these fishing simulations, F across all species was increased and decreased evenly, with F ratios among species defined from single-species estimates of FMSY. This fishing strategy tends to predict relatively high yields for all species in the community at FMSY (Fig. S9) and few trade-offs that result from more uneven distributions of F in relation to FMSY. The sensitivity of sprat to collapse may be an indication of the differing age at selection applied in our model and the ICES assessment models and/or may reflect relatively high estimates of FMSY in the ICES assessment.


Evaluation and management implications of uncertainty in a multispecies size-structured model of population and community responses to fishing.

Thorpe RB, Le Quesne WJ, Luxford F, Collie JS, Jennings S - Methods Ecol Evol (2014)

(a) Probability of species' collapse as a function of fishing mortality, with probability expressed as the proportion of variants in the filtered ensemble (FE) which result in collapses (B < 10% B0). The lightest grey tone indicates probability for the most sensitive species and successively darker tones the probabilities for two or more (up to 14) species. (b) Relationship between mean total yield from the community and fishing mortality. Grey shading and broken lines denote 50% and 90% uncertainty intervals, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390044&req=5

fig06: (a) Probability of species' collapse as a function of fishing mortality, with probability expressed as the proportion of variants in the filtered ensemble (FE) which result in collapses (B < 10% B0). The lightest grey tone indicates probability for the most sensitive species and successively darker tones the probabilities for two or more (up to 14) species. (b) Relationship between mean total yield from the community and fishing mortality. Grey shading and broken lines denote 50% and 90% uncertainty intervals, respectively.
Mentions: Total community yield was maximized when F ≈ 1·6 × FMSY (Fig. 6). Fishing mortality had to be reduced to FMSY or below to avoid all possibility of species' collapse. At 3 × FMSY, an approximation of maximum ‘historic’ F for North Sea target species, mean total yield was predicted to be similar to yield at FMSY, or around 85% of the maximum, but two species were expected to collapse, and probability of collapse was >0·1 for another five species. In these fishing simulations, F across all species was increased and decreased evenly, with F ratios among species defined from single-species estimates of FMSY. This fishing strategy tends to predict relatively high yields for all species in the community at FMSY (Fig. S9) and few trade-offs that result from more uneven distributions of F in relation to FMSY. The sensitivity of sprat to collapse may be an indication of the differing age at selection applied in our model and the ICES assessment models and/or may reflect relatively high estimates of FMSY in the ICES assessment.

Bottom Line: This unfiltered ensemble was reduced to 188 plausible models, the filtered ensemble (FE), by screening outputs against fish abundance data and ecological principles such as requiring species' persistence.Effects of parameter uncertainty on estimates of single-species management reference points for fishing mortality (F MSY, fishing mortality rate providing MSY, the maximum sustainable yield) and biomass (B MSY, biomass at MSY) were evaluated by calculating probability distributions of estimated reference points with the FE.There was a 50% probability that multispecies F MSY could be estimated to within ±25% of its actual value, and a 50% probability that B MSY could be estimated to within ±40% of its actual value.Signal-to-noise ratio was assessed for four community indicators when mortality rates were reduced from current rates to F MSY.Further, the power of an ongoing international monitoring survey to detect predicted responses of size spectrum slope was higher than for other size-based metrics.Synthesis and applications: Application of the ensemble model approach allows explicit representation of parameter uncertainty and supports advice and management by (i) providing uncertainty intervals for management reference points, (ii) estimating working values of reference points that achieve a defined reduction in risk of not breaching the true reference point, (iii) estimating the responsiveness of population, community, food web and biodiversity indicators to changes in F, (iv) assessing the performance of indicators and monitoring programmes and (v) identifying priorities for data collection and changes to model structure to reduce uncertainty.

View Article: PubMed Central - PubMed

Affiliation: Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft Laboratory Lowestoft, NR33 0HT, UK.

ABSTRACT

Implementation of an ecosystem approach to fisheries requires advice on trade-offs among fished species and between fisheries yields and biodiversity or food web properties. However, the lack of explicit representation, analysis and consideration of uncertainty in most multispecies models has limited their application in analyses that could support management advice.We assessed the consequences of parameter uncertainty by developing 78 125 multispecies size-structured fish community models, with all combinations of parameters drawn from ranges that spanned parameter values estimated from data and literature. This unfiltered ensemble was reduced to 188 plausible models, the filtered ensemble (FE), by screening outputs against fish abundance data and ecological principles such as requiring species' persistence.Effects of parameter uncertainty on estimates of single-species management reference points for fishing mortality (F MSY, fishing mortality rate providing MSY, the maximum sustainable yield) and biomass (B MSY, biomass at MSY) were evaluated by calculating probability distributions of estimated reference points with the FE. There was a 50% probability that multispecies F MSY could be estimated to within ±25% of its actual value, and a 50% probability that B MSY could be estimated to within ±40% of its actual value.Signal-to-noise ratio was assessed for four community indicators when mortality rates were reduced from current rates to F MSY. The slope of the community size spectrum showed the greatest signal-to-noise ratio, indicating that it would be the most responsive indicator to the change in fishing mortality F. Further, the power of an ongoing international monitoring survey to detect predicted responses of size spectrum slope was higher than for other size-based metrics.Synthesis and applications: Application of the ensemble model approach allows explicit representation of parameter uncertainty and supports advice and management by (i) providing uncertainty intervals for management reference points, (ii) estimating working values of reference points that achieve a defined reduction in risk of not breaching the true reference point, (iii) estimating the responsiveness of population, community, food web and biodiversity indicators to changes in F, (iv) assessing the performance of indicators and monitoring programmes and (v) identifying priorities for data collection and changes to model structure to reduce uncertainty.

No MeSH data available.