Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points

Stock depletion level is an important concept in the assessment and management of exploited fish stocks because it is often used in conjunction with reference points to infer stock status. Both the depletion level and reference points can be highly dependent on the stock–recruitment relationship. He...

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Main Authors: Mark N. Maunder, Kevin R. Piner
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Fishes
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Online Access:https://www.mdpi.com/2410-3888/9/11/447
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author Mark N. Maunder
Kevin R. Piner
author_facet Mark N. Maunder
Kevin R. Piner
author_sort Mark N. Maunder
collection DOAJ
description Stock depletion level is an important concept in the assessment and management of exploited fish stocks because it is often used in conjunction with reference points to infer stock status. Both the depletion level and reference points can be highly dependent on the stock–recruitment relationship. Here, we show how depletion level is estimated in stock assessment models, what data inform the depletion level, and how the stock–recruitment relationship influences the depletion level. There are a variety of data that provide information on abundance. In addition, to estimate the depletion level, unexploited absolute abundance needs to be determined. This often means extrapolating the abundance back in time to the start of the fishery, accounting for the removals and the productivity. Uncertainty in the depletion level arises because the model can account for the same removals by either estimating low productivity (e.g., low natural mortality) and high carrying capacity or high productivity and a low carrying capacity, and by estimating different relationships between productivity and depletion level, which are strongly controlled by the stock–recruitment relationship. Therefore, estimates of depletion are particularly sensitive to uncertainty in the biological processes related to natural mortality and the stock–recruitment relationship and to growth when length composition data are used. In addition, depletion-based reference points are highly dependent on the stock–recruitment relationship and need to account for recruitment variability, particularly autocorrelation, trends, and regime shifts. Future research needs to focus on estimating natural mortality, the stock–recruitment relationship, asymptotic length, shape of the selectivity curve, or management strategies that are robust to uncertainty in these parameters. Tagging studies, including close-kin mark-recapture, can address some of these issues. However, the stock–recruitment relationship will remain uncertain.
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spelling doaj-art-51e631e331ec42f1915c71fa7b08a6a22025-08-20T02:28:05ZengMDPI AGFishes2410-38882024-11-0191144710.3390/fishes9110447Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference PointsMark N. Maunder0Kevin R. Piner1Inter-American Tropical Tuna Commission, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USAIndependent Researcher, Riverside, WY 82325, USAStock depletion level is an important concept in the assessment and management of exploited fish stocks because it is often used in conjunction with reference points to infer stock status. Both the depletion level and reference points can be highly dependent on the stock–recruitment relationship. Here, we show how depletion level is estimated in stock assessment models, what data inform the depletion level, and how the stock–recruitment relationship influences the depletion level. There are a variety of data that provide information on abundance. In addition, to estimate the depletion level, unexploited absolute abundance needs to be determined. This often means extrapolating the abundance back in time to the start of the fishery, accounting for the removals and the productivity. Uncertainty in the depletion level arises because the model can account for the same removals by either estimating low productivity (e.g., low natural mortality) and high carrying capacity or high productivity and a low carrying capacity, and by estimating different relationships between productivity and depletion level, which are strongly controlled by the stock–recruitment relationship. Therefore, estimates of depletion are particularly sensitive to uncertainty in the biological processes related to natural mortality and the stock–recruitment relationship and to growth when length composition data are used. In addition, depletion-based reference points are highly dependent on the stock–recruitment relationship and need to account for recruitment variability, particularly autocorrelation, trends, and regime shifts. Future research needs to focus on estimating natural mortality, the stock–recruitment relationship, asymptotic length, shape of the selectivity curve, or management strategies that are robust to uncertainty in these parameters. Tagging studies, including close-kin mark-recapture, can address some of these issues. However, the stock–recruitment relationship will remain uncertain.https://www.mdpi.com/2410-3888/9/11/447depletionfisheries managementreference pointstock assessmentstock–recruitment
spellingShingle Mark N. Maunder
Kevin R. Piner
Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points
Fishes
depletion
fisheries management
reference point
stock assessment
stock–recruitment
title Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points
title_full Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points
title_fullStr Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points
title_full_unstemmed Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points
title_short Depletion Estimation, Stock–Recruitment Relationships, and Interpretation of Biomass Reference Points
title_sort depletion estimation stock recruitment relationships and interpretation of biomass reference points
topic depletion
fisheries management
reference point
stock assessment
stock–recruitment
url https://www.mdpi.com/2410-3888/9/11/447
work_keys_str_mv AT marknmaunder depletionestimationstockrecruitmentrelationshipsandinterpretationofbiomassreferencepoints
AT kevinrpiner depletionestimationstockrecruitmentrelationshipsandinterpretationofbiomassreferencepoints