scholarly journals Performance of harvest control rules in a variable environment

2010 ◽  
Vol 67 (5) ◽  
pp. 1051-1062 ◽  
Author(s):  
Thomas Brunel ◽  
Gerjan J. Piet ◽  
Ralf van Hal ◽  
Christine Röckmann
Keyword(s):  
Dynamic Models ◽  
Generalized Additive Models ◽  
Maximum Sustainable Yield ◽  
Additive Models ◽  
Precautionary Approach ◽  
Variable Environment ◽  
Control Rules ◽  
Stock Biomass ◽  
Stock Recruitment ◽  
Harvest Control Rules

AbstractBrunel, T., Piet, G. J., van Hal, R., and Röckmann, C. 2010. Performance of harvest control rules in a variable environment. – ICES Journal of Marine Science, 67: 1051–1062. Population dynamic models used for fisheries management assume that stocks are isolated entities, ignoring the influence of environmental factors on stock productivity. An operating model parameterized for North Sea cod, plaice, and herring is developed, in which the link between recruitment and environment is assumed to be known and described by generalized additive models. This tool is used to compare the performance of harvest control rules (HCRs) when recruitment is independent of the environment or when recruitment is affected by an environment varying according to different scenarios. The first HCR exploited the stock with a fixed fishing mortality (F) corresponding to maximum sustainable yield, and in the second HCR, F was set equal to the precautionary approach F (i.e. Fpa), but reduced from Fpa when stock biomass fell below Bpa. The performance of the HCRs altered only slightly in a randomly varying environment compared with a constant one. For a detrimental change in the environment, however, no HCR could prevent a massive decrease in stock size. The performance of the HCRs was also influenced by the stock characteristics, such as recruitment variability or the shape of the stock–recruitment relationship. The performance of “environmental” HCRs (eHCRs), in which F varies depending on environmental conditions, was compared with that of conventional HCRs. The gain in using the eHCR was small, except for a detrimental change in the environment, where the eHCR performed markedly better than a conventional HCR. The benefits of using the eHCR were the greatest for the stock with the strongest environment–recruitment relationship.

scholarly journals Objectives and harvest control rules in the management of the fishery of Norwegian spring-spawning herring

2009 ◽  
Vol 66 (8) ◽  
pp. 1793-1799 ◽  
Author(s):  
Sigurd Tjelmeland ◽  
Ingolf Røttingen
Keyword(s):  
Stock Assessment ◽  
Maximum Sustainable Yield ◽  
Assessment Model ◽  
Main Element ◽  
Management Objectives ◽  
Control Rules ◽  
Harvest Control Rule ◽  
Stock Recruitment ◽  
Harvest Control Rules

Abstract Tjelmeland, S., and Røttingen, I. 2009. Objectives and harvest control rules in the management of the fishery of Norwegian spring-spawning herring. – ICES Journal of Marine Science, 66: 1793–1799. The main element in the management of the Norwegian spring-spawning herring, as implemented by the coastal states, is to conduct the fishery based on a maximum fishing mortality (F) of 0.125. As the appropriateness of this rule (given the stated objectives) has not yet been tested thoroughly, we set out to do this by long-term simulations, in which we applied a range of alternative stock–recruitment relationships. These different relationships are estimated from historical replicates of the stock, as calculated by the herring-stock assessment model SeaStar. During prognostic simulations, a recruitment model is selected probabilistically for each historical replicate based on Akaike weights. We evaluate whether the management objectives are met by applying the present harvest control rule. Results are given for the current assessment option of natural mortality (M = 0.5) in the oldest aggregated age group and for the assessment option used in 2005 and earlier (M = 0.15). These show that perceptions of the long-term yield differ considerably and that the current management is somewhat on the conservative side from the perspective of maximum sustainable yield.

scholarly journals Implementing the precautionary approach into fisheries management: Making the case for probability-based harvest control rules

2020 ◽  
Author(s):  
Tobias K. Mildenberger ◽  
Casper W. Berg ◽  
Alexandros Kokkalis ◽  
Adrian R. Hordyk ◽  
Chantel Wetzel ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Reference Points ◽  
Production Model ◽  
Scientific Uncertainty ◽  
Precautionary Approach ◽  
Control Rules ◽  
Stock Biomass ◽  
Harvest Control Rules

AbstractThe precautionary approach to fisheries management advocates for risk-averse management strategies that include biological reference points as well as decision rules and account for scientific uncertainty. In this regard, two approaches have been recommended: (i) harvest control rules (HCRs) with threshold reference points to safeguard against low stock biomass, and (ii) the P* method, a ‘probability-based HCR’ that reduces the catch limit as a function of scientific uncertainty (i.e. process, model, and observation uncertainty). This study compares the effectiveness of these precautionary approaches in recovering over-exploited fish stocks with various life-history traits and under a wide range of levels of scientific uncertainty. We use management strategy evaluation based on a stochastic, age-based operating model with quarterly time steps and a stochastic surplus production model. The results show that the most effective HCR includes both a biomass threshold as well as the P* method, and leads to high and stable long-term yield with a decreased risk of low stock biomass. For highly dynamics stocks, management strategies that aim for higher biomass targets than the traditionally used BMSY result in higher long-term yield. This study makes the case for probability-based HCRs by demonstrating their benefit over deterministic HCRs and provides a list of recommendations regarding their definition and implementation.

scholarly journals Substituting model-based indicators in Harvest Control Rules by observations using fuzzy logic methodology

2017 ◽  
Vol 75 (3) ◽  
pp. 977-987
Author(s):  
Arne Eide
Keyword(s):  
Fuzzy Logic ◽  
Mathematical Models ◽  
Stock Assessment ◽  
Decision Rules ◽  
Initial Information ◽  
Stock Size ◽  
Control Rules ◽  
Stock Biomass ◽  
Size Evaluation ◽  
Harvest Control Rules

Abstract Harvest Control Rules are predefined heuristic decision rules to provide quota advices for managed fisheries. Frequently statistical methods and biological assumptions expressed in mathematical models, are used to provide the Harvest Control Rules with initial information (indicators values). The aim of this article is to investigate a possible way forward of replacing these inputs by quantities of measurable observations, e.g. catch-at-age statistics. The article presents a method by which recruitment indexes and stock biomass indicators are obtained by non-parametric use of annual catch-at-age records, without filtering the raw data (observations) through mathematical models. Two related methods, applied on three empirical cases, are provided: First, showing that recruitment strengths of the Northeast Arctic cod, haddock, and saithe stocks, obtained by fuzzy logic methodology, are satisfactory captures by the use of catch-at-age data. Second, stock size indicators are estimated for the three species by the same catch-at-age data. The second task turns out to be more challenging than the first, but also in the case of stock size evaluation, the suggested procedure provides reasonable results when compared to standard stock assessment methods.

scholarly journals Cycles, trends, and residual variation in the Iberian sardine (Sardina pilchardus) recruitment series and their relationship with the environment

2011 ◽  
Vol 69 (5) ◽  
pp. 739-750 ◽  
Author(s):  
M. Begoña Santos ◽  
Rafael González-Quirós ◽  
Isabel Riveiro ◽  
José M. Cabanas ◽  
Carmela Porteiro ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Generalized Additive Models ◽  
Causal Link ◽  
Additive Models ◽  
Dynamic Factor ◽  
Sardina Pilchardus ◽  
Residual Variation ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Short Time

Abstract Santos, M. B., González-Quirós, R., Riveiro, I., Cabanas, J. M., Porteiro, C., and Pierce, G. J. 2012. Cycles, trends, and residual variation in the Iberian sardine (Sardina pilchardus) recruitment series and their relationship with the environment. – ICES Journal of Marine Science, 69: 739–750. Recruitment variability is an important component of the dynamics of Iberian sardine (Sardine pilchardus). Since 2006, poor recruitment has led to a decrease in stock biomass, the latest in a series of such crises for sardine fisheries. Understanding the mechanisms behind recruitment fluctuations has been the objective of many previous studies, and various relationships between recruitment and environmental variables have been proposed. However, such studies face several analytical challenges, including short time-series and autocorrelated data. A new analysis of empirical relationships with environmental series is presented, using statistical methods designed to cope with these issues, including dynamic factor analysis, generalized additive models, and mixed models. Relationships are identified between recruitment and global (number of sunspots), regional (NAOAutumn), and local [winter wind strength, sea surface temperature (SST), and upwelling] environmental variables. Separating these series into trend and noise components permitted further investigation of the nature of the relationships. Whereas the other three environmental variables were related to the trend in recruitment, SST was related to residual variation around the trend, providing stronger evidence for a causal link, possible mechanisms for which are discussed. After the removal of trend and cyclic components, residual variation in recruitment is also weakly related to the previous year's spawning-stock biomass.

scholarly journals Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse1

2006 ◽  
Vol 64 (1) ◽  
pp. 149-159 ◽  
Author(s):  
Kyle W. Shertzer ◽  
Michael H. Prager
Keyword(s):  
Fishery Management ◽  
Economic Loss ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Short Term ◽  
Stock Status ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Stock Collapse

Abstract Shertzer, K. W., and Prager, M. H. 2007. Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse. ICES Journal of Marine Science, 64: 149–159. When a stock is depleted, catch reductions are in order, but typically they are implemented only after considerable delay. Delay occurs because fishery management is political, and stricter management, which involves short-term economic loss, is unpopular. Informed of stock decline, managers often hesitate, perhaps pondering the uncertainty of scientific advice, perhaps hoping that a good year class will render action moot. However, management delay itself can have significant costs, when it exacerbates stock decline. To examine the biological consequences of delay, we simulated a spectrum of fisheries under various degrees of delay in management. Increased delay required larger catch reductions, for more years, to recover benchmark stock status (here, spawning-stock biomass at maximum sustainable yield). Management delay caused stock collapse most often under two conditions: (1) when the stock–recruitment relationship was depensatory, or (2) when catchability, unknown to the assessment, was density-dependent and fishing took juveniles. In contrast, prompt management resulted in quicker recoveries and higher cumulative yields from simulated fisheries. Benefits to stock biomass and fishery yield can be high from implementing management promptly.

scholarly journals Rebuilding depleted fisheries towards BMSY under uncertainty: harvest control rules outperform combined management measures

2020 ◽  
Author(s):  
Ming Sun ◽  
Yunzhou Li ◽  
Yiping Ren ◽  
Yong Chen
Keyword(s):  
Management Practices ◽  
Maximum Sustainable Yield ◽  
Natural Mortality ◽  
Short Term ◽  
Sources Of Uncertainty ◽  
Control Rules ◽  
Management Measures ◽  
Strategy Evaluation ◽  
Harvest Control Rules

Abstract Rebuilding depleted fisheries towards sustainable levels, such as BMSY, is challenging under uncertainty. Although a substantial amount of research has highlighted the importance of accounting for uncertainty in fisheries management, tactical measures remain to be identified. We consider two approaches to achieve this goal: (i) the naive maximum sustainable yield (MSY) approach, combining management measures based on effort control, catch quotas, and spatial–temporal closures, and (ii) the harvest control rules (HCRs) approach, developing HCRs based on short-term or long-term targets. A suite of strategies is developed accordingly and tested with management strategy evaluation for their performance under four sources of uncertainty that may negatively impact management effects, including reduced recruitment strength, increased natural mortality, inadequate implementation error, and varying levels of temporal effort aggregation. Combining management measures using the naive MSY approach is found to perform poorly in tackling uncertainty. Complex HCRs that account for both short-term and long-term BMSY targets can mitigate the adverse effects of uncertainty. The rebuilding target can be only achieved by compromising yield, especially when uncertainties with natural mortality and recruitment are present. Strategies based on catch quotas are prone to all sources of uncertainty, indicating latent risks in many current management practices.

scholarly journals Leveraging scientific uncertainty in fisheries management for estimating among-assessment variation in overfishing limits

2019 ◽  
Vol 77 (2) ◽  
pp. 515-526
Author(s):  
Kristin M Privitera-Johnson ◽  
André E Punt
Keyword(s):  
Fisheries Management ◽  
Previous Analysis ◽  
Risk Tolerance ◽  
Scientific Uncertainty ◽  
New Approach ◽  
Control Rules ◽  
Stock Recruitment ◽  
Us West ◽  
Spawning Biomass ◽  
Harvest Control Rules

Abstract Fisheries management systems can utilize probability-based harvest control rules to incorporate scientific uncertainty and manager risk tolerance when setting catch limits. A precautionary buffer that scales with scientific uncertainty is used to calculate the acceptable biological catch from the overfishing limit (OFL) for US West Coast groundfish and coastal pelagic species. A previous analysis formed the basis for estimating scientific uncertainty as the among-assessment variation in estimates of historical spawning biomass time-series. This “historical biomass” approach may underestimate scientific uncertainty, because the OFL is a function of estimated exploitable biomass and fishing mortality. We developed a new approach that bases the calculation of scientific uncertainty on projected spawning biomass (SSB) and OFLs, accounting for uncertainty in recruitment and among-assessment variation. OFL projections yielded a higher estimate of uncertainty than SSB (0.502 vs. 0.413 for 25-year projections and 0.562 vs. 0.384 for a 1-year projection, assuming a deterministic stock-recruitment relationship). Assuming a stochastic stock-recruitment relationship produced smaller estimates of uncertainty (0.436, 25-year OFL projections; 0.452, 1-year OFL projections; 0.360, 25-year SSB projections; 0.318, 1-year SSB projections). The projection-based approach presented herein is applicable across stocks and regions that conduct assessments with sufficient and consistent outputs for calculating an OFL.

scholarly journals Evaluating the parameters of a MSY control rule for the Bristol Bay, Alaska, stock of red king crabs

2007 ◽  
Vol 64 (5) ◽  
pp. 995-1005 ◽  
Author(s):  
M. S. M. Siddeek ◽  
J. Zheng
Keyword(s):  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Stochastic Simulations ◽  
Bristol Bay ◽  
Control Rule ◽  
Single Sex ◽  
Control Rules ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Spawning Potential Ratio

Abstract Siddeek, M. S. M. and Zheng, J. 2007. Evaluating the parameters of a MSY control rule for the Bristol Bay, Alaska, stock of red king crabs. – ICES Journal of Marine Science, 64: 995–1005. A maximum sustainable yield (MSY) control rule, which defines the level of overfishing, and determines the control rule parameters based on an age-, sex-, and size-structured assessment for Bristol Bay red king crabs (Paralithodes camtschaticus) is developed. Fx% (F corresponding to x% spawning potential ratio) is used as a proxy for FMSY and a minimum spawning-stock biomass (to open the fishery) for incorporation into the MSY control rule. The performance of the selected MSY control rule and the associated target control rule is evaluated using stochastic simulations. F50% is a reasonable proxy for FMSY when effective spawning biomass is used as the stock biomass in the stock-recruitment relationship. This method with appropriate modifications might be used for determining biological reference points and developing control rules for any crustacean stock with discrete growth, complex reproductive dynamics, and single sex exploitation.

Optimal effort controls for the multispecies groundfish complex in New England: what might have been

2003 ◽  
Vol 60 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Daniel S Holland ◽  
Jean-Jacques Maguire
Keyword(s):  
New England ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Fishing Mortality ◽  
Alternative Control ◽  
Control Rules ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Age Structured ◽  
Groundfish Fishery

Age-structured models are used to calculate catches and revenues of the principal stocks in the northeast multispecies groundfish fishery over the 1982–1997 period assuming alternative control rules on fishing effort had been employed. Various static levels of nominal effort are compared with controls that maintain fishing mortality below overfishing thresholds for all stocks. An unambiguous result from this analysis is that substantial reductions in fishing effort would have increased the value of the fishery even if resulting increases in spawning stock biomass (SSB) had not increased recruitment. Simple controls on nominal effort designed to maximize revenues would have provided nearly equivalent revenues to those achieved by maintaining fishing mortality for each stock at its individual maximum sustainable yield (FMSY) but would have led to overfishing of some stocks. Without the ability to tune the relative catches across stocks, strict controls on effort designed to prevent overfishing on individual stocks would likely have resulted in significantly lower and more variable revenues. Achieving SSB targets for three stocks would not have been possible given the observed recruitment.

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