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Rishi Sharma
Food and Agriculture Organization of the United Nations Fisheries and Aquaculture Rome Italy

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Original article
Published: 19 July 2021 in Fish and Fisheries
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Implementation of the United Nations Sustainable Development Goals requires assessments of the global state of fish populations. While we have reliable estimates of stock status for fish populations accounting for approximately half of recent global catch, our knowledge of the state of the majority of the world's “unassessed” fish stocks remains highly uncertain. Numerous publications have produced estimates of the global status of these unassessed fisheries, but limited quantity and quality of data along with methodological differences have produced counterintuitive and conflicting results. Here, we show that despite numerous efforts, our understanding of the status of global fish stocks remains incomplete, even when new sources of broadly available data are added. Estimates of fish populations based primarily on catch histories on average performed 25% better than a random guess. But, on average, these methods assigned fisheries to the wrong FAO status category 57% of the time. Within these broad summaries, the performance of models trained on our tested data sources varied widely across regions. Substantial improvements to estimates of the state of the world's exploited fish populations depend more on expanded collection of new information and efficient use of existing data than development of new modelling methods.

ACS Style

Daniel Ovando; Ray Hilborn; Cole Monnahan; Merrill Rudd; Rishi Sharma; James T. Thorson; Yannick Rousseau; Yimin Ye. Improving estimates of the state of global fisheries depends on better data. Fish and Fisheries 2021, 1 .

AMA Style

Daniel Ovando, Ray Hilborn, Cole Monnahan, Merrill Rudd, Rishi Sharma, James T. Thorson, Yannick Rousseau, Yimin Ye. Improving estimates of the state of global fisheries depends on better data. Fish and Fisheries. 2021; ():1.

Chicago/Turabian Style

Daniel Ovando; Ray Hilborn; Cole Monnahan; Merrill Rudd; Rishi Sharma; James T. Thorson; Yannick Rousseau; Yimin Ye. 2021. "Improving estimates of the state of global fisheries depends on better data." Fish and Fisheries , no. : 1.

Journal article
Published: 28 May 2021 in Sustainability
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Catch-only models (COMs) have been the focus of ongoing research into data-poor stock assessment methods. Two of the most recent models that are especially promising are (i) CMSY+, the latest refined version of CMSY that has progressed from Catch-MSY, and (ii) SRA+ (Stock Reduction Analysis Plus), one of the latest developments in the field. Comparing COMs and evaluating their relative performance is essential for determining the state of regional and global fisheries that may be lacking necessary data that would be required to run traditional assessment models. In this paper we interrogate how performance of COMs can be improved by incorporating additional sources of information. We evaluate the performance of COMs on a dataset of 48 data-rich ICES (International Council for the Exploration of Seas) stock assessments. As one measure of performance, we consider the ability of the model to correctly classify stock status using FAO’s 3-tier classification that is also used for reporting on sustainable development goals to the UN. Both COMs showed notable bias when run with their inbuilt default heuristics, but as the quality of prior information increased, classification rates for the terminal year improved substantially. We conclude that although further COM refinements show some potential, most promising is the ongoing research into developing biomass or fishing effort priors for COMs in order to be able to reliably track stock status for the majority of the world’s fisheries currently lacking stock assessments.

ACS Style

Rishi Sharma; Henning Winker; Polina Levontin; Laurence Kell; Dan Ovando; Maria Palomares; Cecilia Pinto; Yimin Ye. Assessing the Potential of Catch-Only Models to Inform on the State of Global Fisheries and the UN’s SDGs. Sustainability 2021, 13, 6101 .

AMA Style

Rishi Sharma, Henning Winker, Polina Levontin, Laurence Kell, Dan Ovando, Maria Palomares, Cecilia Pinto, Yimin Ye. Assessing the Potential of Catch-Only Models to Inform on the State of Global Fisheries and the UN’s SDGs. Sustainability. 2021; 13 (11):6101.

Chicago/Turabian Style

Rishi Sharma; Henning Winker; Polina Levontin; Laurence Kell; Dan Ovando; Maria Palomares; Cecilia Pinto; Yimin Ye. 2021. "Assessing the Potential of Catch-Only Models to Inform on the State of Global Fisheries and the UN’s SDGs." Sustainability 13, no. 11: 6101.

Original article
Published: 01 July 2020 in Fish and Fisheries
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The five Regional Fishery Management Organizations dedicated to tunas (tRFMOs) are all either developing or implementing Management Strategy Evaluations (MSEs) to provide advice for the stocks under their competencies. Providing a comparative overview will help tRFMOs to learn from one another and to collaborate on common solutions and may also help to more clearly define the challenges of building decision support tools in contexts of large scientific uncertainty and where management requires cooperation across multiple stakeholders characterized by unequal power and divergent interests. For example, our overview showed that in most cases, a grid‐based design with an emphasis on structural uncertainty has been adopted. However, uncertainties such as sampling errors and non‐stationarity of important ecological processes, which are of potentially equal significance for demonstrating robustness of management procedures, were not considered. This paper identifies key issues for operating model (OM) design that challenges the tRFMOs, compares how these challenges are being met, summarizes what lessons have been learned and suggests a way forward. Although the current approach of using assessment models as the basis for OM design is a reasonable starting point, improvements should be made to the conditioning of OMs, especially with respect to enabling the inclusion of other important processes and uncertainties that are difficult to account for in stock assessments but that can crucially affect the robustness of advice. Attempts should also be made to improve documentation and communication of uncertainties that are included and those that are excluded from consideration in the process.

ACS Style

Rishi Sharma; Polina Levontin; Toshihide Kitakado; Laurence Kell; Iago Mosqueira; Ai Kimoto; Rob Scott; Carolina Minte‐Vera; Paul De Bruyn; Yimin Ye; Jana Kleineberg; Jo Lindsay Walton; Shana Miller; Arni Magnusson. Operating model design in tuna Regional Fishery Management Organizations: Current practice, issues and implications. Fish and Fisheries 2020, 21, 940 -961.

AMA Style

Rishi Sharma, Polina Levontin, Toshihide Kitakado, Laurence Kell, Iago Mosqueira, Ai Kimoto, Rob Scott, Carolina Minte‐Vera, Paul De Bruyn, Yimin Ye, Jana Kleineberg, Jo Lindsay Walton, Shana Miller, Arni Magnusson. Operating model design in tuna Regional Fishery Management Organizations: Current practice, issues and implications. Fish and Fisheries. 2020; 21 (5):940-961.

Chicago/Turabian Style

Rishi Sharma; Polina Levontin; Toshihide Kitakado; Laurence Kell; Iago Mosqueira; Ai Kimoto; Rob Scott; Carolina Minte‐Vera; Paul De Bruyn; Yimin Ye; Jana Kleineberg; Jo Lindsay Walton; Shana Miller; Arni Magnusson. 2020. "Operating model design in tuna Regional Fishery Management Organizations: Current practice, issues and implications." Fish and Fisheries 21, no. 5: 940-961.