Evaluating a prior on relative stock status using simplified age-structured models

Cope, Jason M.; Thorson, James T.; Wetzel, Chantell R.; DeVore, John

doi:10.1016/j.fishres.2014.07.018

Cited by 26 publications

(19 citation statements)

References 25 publications

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“…Key potential areas for future improvement include better informed prior distributions for final status in different regions, including priors that account for the characteristics of fishery resources in different regions (Cope et al . ), inclusion of existing survey and fishery data (Thorson et al . ), and evaluation of how well these models inform management strategies for data‐limited fisheries.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, the superensemble method as applied here is trained on simulation results, and therefore may not capture other features in the dynamics of real populations including the impact of factors such as climate change. Key potential areas for future improvement include better informed prior distributions for final status in different regions, including priors that account for the characteristics of fishery resources in different regions (Cope et al 2015), inclusion of existing survey and fishery data (Thorson et al 2012), and evaluation of how well these models inform management strategies for data-limited fisheries.…”

Section: Discussionmentioning

confidence: 99%

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Applying a New Ensemble Approach to Estimating Stock Status of Marine Fisheries around the World

Rosenberg

Kleisner

Afflerbach

et al. 2017

CONSERVATION LETTERS

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The exploitation status of marine fisheries stocks worldwide is of critical importance for food security, ecosystem conservation, and fishery sustainability. Applying a suite of data-limited methods to global catch data, combined through an ensemble modeling approach, we provide quantitative estimates of exploitation status for 785 fish stocks. Fifty-three percent (414 stocks) are below B MSY and of these, 265 are estimated to be below 80% of the B MSY level. While the 149 stocks above 80% of B MSY are conventionally considered "fully exploited," stocks staying at this level for many years, forego substantial yield. Our results enable managers to consider more detailed information than simply a categorization of stocks as "fully" or "over" exploited. Our approach is reproducible, allows consistent application to a broad range of stocks, and can be easily updated as new data become available. Applied on an ongoing basis, this approach can provide critical, more detailed information for resource management for more exploited fish stocks than currently available.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Applying a New Ensemble Approach to Estimating Stock Status of Marine Fisheries around the World

Rosenberg

Kleisner

Afflerbach

et al. 2017

CONSERVATION LETTERS

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“…Alternative ways of deriving this important stock metric would be a valuable contribution to management. Cope et al [31] developed a method that estimates a stock status prior using Productivity-Susceptibility Analysis (PSA) vulnerability scores, being the first step towards solutions for defining stock status in data-limited situations. Other possible alternatives for defining stock status, when facing data limitations, include the utilization of information from species with similar exploitation/biology [32].…”

Section: Introductionmentioning

confidence: 99%

Eliciting expert knowledge to inform stock status for data-limited stock assessments

2019

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Data-limited fisheries are a major challenge for stock assessment analysts, as many traditional data-rich models cannot be implemented. Approaches based on stock reduction analysis offer simple ways to handle low data availability, but are particularly sensitive to assumptions on relative stock status (i.e., current biomass compared to unperturbed biomass). For the vast majority of data-limited stocks, stock status is unmeasured. The present study presents a method to elicit expert knowledge to inform stock status and a novel, user-friendly on-line application for expert elicitation. Expert opinions are compared to stock status derived from data-rich models. Here, it is evaluated how experts with different levels of experience in stock assessment performed relative to each other and with different qualities of data. Both "true" stock status and expert experience level were identified as significant factors accounting for the error in stock status elicitation. Relative stock status was the main driver of imprecision in the stock status prior (e.g., lower stock status had more imprecision in elicited stock status). Data availability and life-history information were not identified to be significant variables explaining imprecision in elicited stock status. All experts, regardless of their experience level, appeared to be risk neutral in the central tendency of stock status. Given the sensitivity to stock status misspecification for some popular data-limited methods, stock status can be usefully elicited from experts, but expert subjectivity and experience should be taken under consideration when applying those values.

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“…Using all available data (FULL run), the current biomass was estimated as 7% of the carrying capacity and B MSY as 32 000 tonnes (50% of K). Cope et al (2015) derived an empirical relationship between species vulnerability to fishing and depletion rate of (more or less) unmanaged stocks for the US Pacific coast. For thornback ray in the Celtic Sea, McCully et al (2015) estimated a vulnerability score of 1.61.…”

Section: Thornback Ray In the Bay Of Biscaymentioning

confidence: 99%

“…For thornback ray in the Celtic Sea, McCully et al (2015) estimated a vulnerability score of 1.61. For this level of vulnerability the empirical relationship of Cope et al (2015) gives a depletion rate of 0.54. If our estimates are correct, the depletion of thornback ray in the Bay of Biscay is rather severe, suggesting either vulnerability to fishing is higher than in the Celtic Sea or that unmanaged fishing pressure was much higher than on US Pacific coast, or both.…”

Section: Thornback Ray In the Bay Of Biscaymentioning

confidence: 99%

A Bayesian state-space model to estimate population biomass with catch and limited survey data: application to the thornback ray (Raja clavata) in the Bay of Biscay

Marandel

Lorance

Trenkel

2016

Aquat. Living Resour.

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The thornback ray (Raja clavata) in the Bay of Biscay is presumed to have declined during the 20 th Century. To evaluate this decline and estimate biomass trajectories, a hypothetical catch time series was created for the period 1903-2013. A Bayesian state-space biomass production model with a Schaefer production function was fitted to the hypothetical catch time series and to a shorter research vessel Catch Per Unit Eeffort (CPUE) time series (1973-2013, with missing years). A censored likelihood made it possible to obtain biomass estimates without a CPUE time series or only with an estimate of biomass depletion. A simulation-estimation approach showed a high sensitivity of results to the prior for the intrinsic growth rate. The model provided biomass trajectories which corroborated and quantified the decline of the Bay of Biscay population. The estimated biomass corresponding to the maximum sustainable yield, B MSY , was 32 000 tonnes, which is 17 times higher than the estimated biomass in 2014. The biomass estimates obtained without a CPUE time series were highly uncertain. Adding a current biomass depletion observation improved precision, though the biomass time trend was sensitive to this value. Results should be interpreted carefully as several assumptions were necessary to create the long catch time series and to define informative priors, notably for the intrinsic growth rate. Despite this, the results confirm the depleted state of the thornback ray in the Bay of Biscay with the estimated biomass in 2014 being around 3% of carrying capacity.

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Evaluating a prior on relative stock status using simplified age-structured models

Cited by 26 publications

References 25 publications

Applying a New Ensemble Approach to Estimating Stock Status of Marine Fisheries around the World

Applying a New Ensemble Approach to Estimating Stock Status of Marine Fisheries around the World

Eliciting expert knowledge to inform stock status for data-limited stock assessments

A Bayesian state-space model to estimate population biomass with catch and limited survey data: application to the thornback ray (Raja clavata) in the Bay of Biscay

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