scholarly journals Complex assessments or simple management procedures for efficient fisheries management: a comparative study

2014 ◽  
Vol 72 (1) ◽  
pp. 262-274 ◽  
Author(s):  
H. F. Geromont ◽  
D. S. Butterworth
Keyword(s):  
Fishery Management ◽  
Stock Assessment ◽  
Assessment Methods ◽  
Essential Requirement ◽  
Fish Stocks ◽  
Control Rules ◽  
Management Procedures ◽  
Simple Rules ◽  
Sound Management

Abstract Complex stock assessment methods are data- and expertise-hungry, with the annual updates of catch-at-age data and models typically seen as an essential requirement for sound management. But are the heavy commitments of resources required for this level of annual intervention really necessary to achieve efficient long-term fishery management? This question is addressed through a retrospective analysis of management performance over the last 20 years for four North Atlantic fish stocks. The assessments for two of these stocks have exhibited fairly strong retrospective patterns. The actual assessment advice for these stocks was provided based on complex assessment methods making use of age data. The outcomes are compared with what could have been achieved with much simpler catch control rules based upon age-aggregated survey indices alone. Even for the stocks whose assessments exhibit retrospective patterns, these simple rules can achieve virtually equivalent catch and risk performance, with much less interannual TAC variability, compared with what actually occurred over the past 20 years.

scholarly journals Stock assessment methods for sustainable fisheries

2014 ◽  
Vol 72 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Steven X. Cadrin ◽  
Mark Dickey-Collas
Keyword(s):  
Fishery Management ◽  
Stock Assessment ◽  
Management Strategies ◽  
Assessment Methods ◽  
Reference Points ◽  
Fish Stock ◽  
Mortality Trends ◽  
Sustainable Fisheries ◽  
Management Procedures ◽  
Pseudo Data

Abstract This special volume of the ICES Journal compiles contributions from the World Conference on Stock Assessment Methods for Sustainable Fisheries (July 2013, Boston, USA). The conference was the product of a strategic initiative on stock assessment methods that engaged many national and regional fishery management organizations to assure that scientists can apply the most appropriate methods when developing management advice. An inclusive workshop was designed to evaluate the performance of a variety of model categories by applying multiple models to selected case study data as well as simulated pseudo-data that had realistic measurement error. All model applications had difficulties in recovering the simulated stock and fishing mortality trends, particularly at the end of the assessment time series, when they are most important for informing fishery management. This general result suggests that the next steps in evaluating the performance of stock assessment methods should include stock status relative to sustainable reference points, catch advice, multi-model consideration, and alternative management procedures. Recognition of the limitations of conventional stock assessment methods should promote further development of data-limited approaches, methods with time-varying parameters, or spatial complexity, and a more revolutionary shift towards the application of multispecies and ecosystem models. The contributions in this volume address methodological themes that are expected to improve the scientific basis of fishery management. Furthermore, the limitations of stock assessment methods and associated uncertainty should be more extensively considered in fishery management strategies and tactical decisions. Recommendations developed during the conference called for the establishment of a global initiative to synthesize regional advances, form guidance on best practices, promote strategic investments, and highlight research needs for fish stock assessments.

scholarly journals Designing tools to evaluate fishery management strategies: can the scientific community deliver?

2007 ◽  
Vol 64 (6) ◽  
pp. 1077-1084 ◽  
Author(s):  
Jon T. Schnute ◽  
Mark N. Maunder ◽  
James N. Ianelli
Keyword(s):  
Programming Languages ◽  
Scientific Community ◽  
Fishery Management ◽  
Stock Assessment ◽  
Management Strategies ◽  
Academic Disciplines ◽  
Strategy Evaluation ◽  
Management Procedures ◽  
Human Skills ◽  
Testing Management

Abstract Schnute, J. T., Maunder, M. N., and Ianelli, J. N. 2007. Designing tools to evaluate fishery management strategies: can the scientific community deliver? – ICES Journal of Marine Science, 64: 1077–1084. Techniques for quantitative fishery management have evolved rapidly during a period when computers, programming languages, and computational algorithms have also changed dramatically. Despite these advances, many stock assessment methods remain untested. A process of management strategy evaluation (MSE) could potentially rectify this problem, but it would require a framework in which to conduct systematic tests. We survey the tools currently used for stock assessments and discuss the development of new standards for testing management procedures. A successful project would depend on human skills scattered among various nations, organizations, and academic disciplines. Analogies from civil engineering illustrate the discipline and collaboration required for an effective outcome. If the world community of fishery scientists could design, build, and support such a project, it would revolutionize the theory, teaching, and practice of scientific fishery management.

Assessing the sensitivity of data-limited methods (DLMs) to the estimation of life-history parameters from length–frequency data

2018 ◽  
Vol 75 (10) ◽  
pp. 1563-1572 ◽  
Author(s):  
Ming Sun ◽  
Chongliang Zhang ◽  
Yong Chen ◽  
Binduo Xu ◽  
Ying Xue ◽  
...  
Keyword(s):  
Life History ◽  
Stock Assessment ◽  
Stock Management ◽  
Larimichthys Polyactis ◽  
Life History Parameters ◽  
Control Rules ◽  
Strategy Evaluation ◽  
Management Procedures ◽  
Spawning Potential Ratio ◽  
Harvest Control Rules

Data-limited methods (DLMs) in stock assessment may provide potential critical information for data-limited stock management. However, the sensitivity of those methods to life-history parameters is largely unknown, resulting in extra uncertainty and consequent risks. In the present study, we designed six parallel workflows (WFs) to incorporate classic and state-of-the-art methods of estimating life-history parameters and examined their influences on the assessment of small yellow croaker (Larimichthys polyactis) in Haizhou Bay, China. The sensitivity was evaluated with three objectives: (i) the evaluation of stock status with the spawning potential ratio following different assumptions; (ii) the length-based harvest control rules derived from three management procedures; and (iii) the management performance of these harvest control rules with simulation of management strategy evaluation. The results showed considerable sensitivity regarding the three objectives to the estimations with different WFs, indicating the previous practice of credulously accepting empirical values and indiscriminately selecting references are inadvisable. We also identified the most appropriate WFs used for different purposes with limited data, aiming to provide more reliable inputs for effective fisheries management.

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 Combined effects of exploitation and temperature on fish stocks in the Northeast Atlantic

2014 ◽  
Vol 71 (7) ◽  
pp. 1554-1562 ◽  
Author(s):  
Tristan Rouyer ◽  
Jean-Marc Fromentin ◽  
Manuel Hidalgo ◽  
Nils C. Stenseth
Keyword(s):  
Geographical Location ◽  
Geographic Location ◽  
Effect Of Temperature ◽  
Fish Stock ◽  
Combined Effects ◽  
Fish Stocks ◽  
Northeast Atlantic ◽  
Middle Range ◽  
Management Procedures

Abstract Fish stock fluctuations are affected by two potentially confounding forces: the removal of individuals by fisheries and climatic variations affecting the productivity of fish populations. Disentangling the relative importance of these forces has thus been a question of primary importance for fisheries management and conservation. Through the analysis of long-term time-series for 27 fish stocks from the Northeast Atlantic, the present study shows that the sign and intensity of the effect of temperature on biomass are dependent on the geographical location: the stocks located at the southernmost and northernmost latitudes of our study displayed stronger associations with temperature than the stocks located in the middle range of latitudes. As a consequence, the investigation of the combined effects of exploitation and the environment revealed that the stocks at the northern/southern boundaries of the spatial extent of the species were more prone to combined effects. The interplay between geographic location, climate and exploitation thus plays a significant role in fish stock productivity, which is generally ignored during assessment, thus affecting management procedures.

Increase in growth rates of southern bluefin tuna (Thunnus maccoyii) over four decades: 1960 to 2000

2004 ◽  
Vol 61 (2) ◽  
pp. 307-322 ◽  
Author(s):  
Tom Polacheck ◽  
J Paige Eveson ◽  
Geoff M Laslett
Keyword(s):  
Stock Assessment ◽  
Temporal Trends ◽  
Integrated Approach ◽  
Bluefin Tuna ◽  
Fish Stocks ◽  
Southern Bluefin Tuna ◽  
History Of ◽  
The 1960S ◽  
Length Frequency Data

Estimates of long-term temporal trends and variability in growth are often not available for many commercially exploited fish stocks. An integrated estimation framework that combines growth information from tagging studies, direct age estimates from hard parts, and modal progression estimates from length–frequency data is applied to data on southern bluefin tuna (Thunnus maccoyii, SBT) collected over four decades, from 1960 to 2000. By using an integrated approach, a comprehensive set of growth estimates can be obtained for each of these four decades even though substantive deficiencies exist in the coverage of the historical data from any single source. The results confirm previous findings that cohorts from the 1980s grew substantially faster at young ages than cohorts from the 1960s. The results also suggest that the 1970s was a period of transition and that growth of fish up to about age 4 was faster in the 1990s than in the 1980s. The changes in SBT growth over these four decades are consistent with density-dependent responses given the history of exploitation and stock assessment estimates of changes in population size.

scholarly journals An evaluation of acceptable biological catch (ABC) harvest control rules designed to limit overfishing

2017 ◽  
Vol 74 (7) ◽  
pp. 1028-1040 ◽  
Author(s):  
John Wiedenmann ◽  
Michael Wilberg ◽  
Andrea Sylvia ◽  
Thomas Miller
Keyword(s):  
Fishery Management ◽  
Short Interval ◽  
Assessment Model ◽  
Scientific Uncertainty ◽  
High Yield ◽  
Management Objectives ◽  
Control Rules ◽  
Average Biomass ◽  
Harvest Control Rules

In this paper we developed a simulation model to evaluate a range of acceptable biological catch (ABC) control rules to determine their relative performance at achieving common fishery management objectives. We explored a range of scenarios to determine robustness of a control rule to different situations and found that across scenarios the control rules that used a buffer to account for scientific uncertainty when setting the ABC were able to limit the frequency of overfishing. Modest buffers when setting the ABC were generally effective at limiting overfishing, but larger buffers resulted in higher average biomass, similar long-term benefits to the fishery (high yield, low variability in yield), more rapid recovery of depleted populations, and a lower risk of the population being overfished, and these results were robust to the level of uncertainty in the assessment model estimates. In addition, fixing the ABC over the interval between assessments and having a short interval between assessments was generally more effective at meeting management objectives than using projections and having a long assessment interval.

scholarly journals Generic management procedures for data-poor fisheries: forecasting with few data

2014 ◽  
Vol 72 (1) ◽  
pp. 251-261 ◽  
Author(s):  
H. F. Geromont ◽  
D. S. Butterworth
Keyword(s):  
Scientific Management ◽  
Fish Stocks ◽  
Control Rules ◽  
Management Procedure ◽  
Key Characteristics ◽  
Management Procedures ◽  
Wide Range ◽  
Generic Management ◽  
Few Data ◽  
Index Of Abundance

Abstract The majority of fish stocks worldwide are not managed quantitatively as they lack sufficient data, particularly a direct index of abundance, on which to base an assessment. Often these stocks are relatively “low value”, which renders dedicated scientific management too costly, and a generic solution is therefore desirable. A management procedure (MP) approach is suggested where simple harvest control rules are simulation tested to check robustness to uncertainties. The aim of this analysis is to test some very simple “off-the-shelf” MPs that could be applied to groups of data-poor stocks which share similar key characteristics in terms of status and demographic parameters. For this initial investigation, a selection of empirical MPs is simulation tested over a wide range of operating models (OMs) representing resources of medium productivity classified as severely depleted, to ascertain how well these different MPs perform. While the data-moderate MPs (based on an index of abundance) perform somewhat better than the data-limited ones (which lack such input) as would be expected, the latter nevertheless perform surprisingly well across wide ranges of uncertainty. These simple MPs could well provide the basis to develop candidate MPs to manage data-limited stocks, ensuring if not optimal, at least relatively stable sustainable future catches.

Comparative performance of data-poor CMSY and data-moderate SPiCT stock assessment methods when applied to data-rich, real-world stocks

2020 ◽  
Author(s):  
Paul Bouch ◽  
Cóilín Minto ◽  
Dave G Reid
Keyword(s):  
Stock Assessment ◽  
Assessment Methods ◽  
Production Model ◽  
Fishing Mortality ◽  
Comparative Performance ◽  
Fish Stocks ◽  
Surplus Production ◽  
Stock Biomass ◽  
Surplus Production Model ◽  
The Status

Abstract All fish stocks should be managed sustainably, yet for the majority of stocks, data are often limited and different stock assessment methods are required. Two popular and widely used methods are Catch-MSY (CMSY) and Surplus Production Model in Continuous Time (SPiCT). We apply these methods to 17 data-rich stocks and compare the status estimates to the accepted International Council for the Exploration of the Sea (ICES) age-based assessments. Comparison statistics and receiver operator analysis showed that both methods often differed considerably from the ICES assessment, with CMSY showing a tendency to overestimate relative fishing mortality and underestimate relative stock biomass, whilst SPiCT showed the opposite. CMSY assessments were poor when the default depletion prior ranges differed from the ICES assessments, particularly towards the end of the time series, where some stocks showed signs of recovery. SPiCT assessments showed better correlation with the ICES assessment but often failed to correctly estimate the scale of either F/FMSY of B/BMSY, with the indices lacking the contrast to be informative about catchability and either the intrinsic growth rate or carrying capacity. Results highlight the importance of understanding model tendencies relative to data-rich approaches and warrant caution when adopting these models.

Comparing performance of catch-based and length-based stock assessment methods in data-limited fisheries

2020 ◽  
Vol 77 (6) ◽  
pp. 1026-1037 ◽  
Author(s):  
Maite Pons ◽  
Jason M. Cope ◽  
Laurence T. Kell
Keyword(s):  
Closed Loop ◽  
Stock Assessment ◽  
Maximum Sustainable Yield ◽  
Assessment Methods ◽  
Small Scale ◽  
Small Scale Fisheries ◽  
Management Procedures ◽  
Spawning Potential Ratio ◽  
The Common ◽  
The One

The quantity of data from many small-scale fisheries is insufficient to allow for the application of conventional assessment methods. Even though in many countries they are moving to closed-loop simulations to assess the performance of different management procedures in data-limited situations, managers in most developing countries are still demanding information on stock status. In this study we use the common metric of harvest rate to evaluate and compare the performance of the following catch-only and length-only assessment models: catch – maximum sustainable yield (Catch-MSY), depletion-based stock reduction analysis (DBSRA), simple Stock Synthesis (SSS), an extension of Catch-MSY (CMSY), length-based spawning potential ratio (LBSPR), length-based integrated mixed effects (LIME), and length-based Bayesian (LBB). In general, results were more biased for slightly depleted than for highly depleted stocks and for long-lived than for short-lived species. Length-based models, such as LIME, performed as well as catch-based methods in many scenarios, and among the catch-based models, the one with the best performance was SSS followed by CMSY.

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