Jason M. Cope

Jason M. Cope
Northwest Fisheries Science Center · Fishery Resource Analysis and Monitoring Division

Ph.D., M.S., B.A.

About

97
Publications
34,038
Reads
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2,652
Citations
Additional affiliations
September 2007 - present
Northwest Fisheries Science Center
Position
  • Resrch Fishery Biologist

Publications

Publications (97)
Article
Full-text available
The natural mortality rate M is a key parameter in estimating the productivity of a fish stock. However, it is quite difficult to estimate given its correlation with other parameters, variation in processes governing population dynamics and data acquisition, as well as other factors such as ageing error. Meta-analytical approaches relating M to oth...
Article
Natural morality (M) is a notoriously difficult population parameter to estimate, yet it is also one of the most important measures of life history that sets, as Beverton and Holt called it, "the course of events". Stock assessments that include this parameter often show great sensitivity to its value, reflecting the need to characetrize the uncert...
Article
Full-text available
Marine population modeling, which underpins the scientific advice to support fisheries interventions, is an active research field with recent advancements to address modern challenges (e.g., climate change) and enduring issues (e.g., data limitations). Based on discussions during the 'Land of Plenty' session at the 2021 World Fisheries Congress, we...
Article
Full-text available
Accurate maturity schedules are critical to ensure that stock assessment models can track changes in spawning stock biomass. To generate updated maturity estimates, the Northwest Fisheries Science Center’s Fishery Resource Analysis and Monitoring Division instituted a reproductive biology program in 2009. This program uses histological analysis of...
Article
Full-text available
As the world population grows, fisheries practitioners will be under increased pressure to address global challenges in data-limited fisheries management. With a focus on addressing localized and case-specific management needs, we provide a practical guide to the design and development of multi-indicator frameworks for fishery management. In a data...
Technical Report
Full-text available
Stock assessment report available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Technical Report
Stock assessment available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Technical Report
Stock assessment available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Technical Report
Stock assessment available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Technical Report
Stock assessment available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Technical Report
Stock assessment available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Technical Report
Full-text available
Stock assessment available at: https://www.pcouncil.org/stock-assessments-star-reports-stat-reports-rebuilding-analyses-terms-of-reference/groundfish-stock-assessment-documents/
Article
Data availability, and unreported and unregulated fishing are significant obstacles to evaluating stock status, especially in tropical areas. Limitations in data quantity and quality can lead to model misspecification and erroneous data treatments, potentially causing important changes in model outputs and subsequent management implications. Red sn...
Article
Full-text available
Many fisheries in the world are data-moderate, with data types (e.g., total removals, abundance indices, and biological composition data) of varied quality (e.g., limited time series or representative samples) or available data. Integrated stock assessments are useful tools for data-moderate fisheries as they can include all available information,...
Article
Full-text available
Understanding the environmental and anthropogenic drivers of spatial patterns in life history variation for exploited fish populations is important when making management decisions and designating stock boundaries. These considerations are especially germane for stocks that are overfished or recently rebuilt, such as lingcod Ophiodon elongatus , a...
Article
The predominant policy for remedying the world fishing crisis aims at maximum sustainable yield (MSY) by adjusting gear selectivity and fishing effort to maintain sustainable stock levels. The yellowfin tuna (Thunnus albacares) fishery in the Sea of Oman has experienced intense increases in removals since 1980, with particularly high levels since t...
Article
We analysed the long-term changes in the population dynamics and life history of whitemouth croaker (Micropogonias furnieri) off Southern Brazil, to understand how four decades of heavy fishing (1976–2017) has affected its population dynamics. In the first three decades, size and age structure were eroded with the loss of the larger (> 60 cm total...
Article
Natural mortality (M) is often considered to be one of the most important parameters in a fish stock assessment and affects productivity estimates for the population. However, it is also among the most difficult parameters to estimate using commonly available data. The magnitude of error (both bias and variance) when estimating this parameter can b...
Article
Full-text available
We outline a new flexible method for estimating maturity that incorporates skip spawning, which can lead to non-asymptotic behavior in the population maturity schedule. This new approach aids fisheries managers who seek to understand marine species’ responses to changing oceans. In an effort to assess shifts in maturity and spawning behavior of wes...
Article
Full-text available
We present a visual and tabular representation of fisheries stock assessment model outputs to rapidly examine and effectively communicate sensitivity analysis results from numerous alternative model comparisons. This approach uses multiple output metrics to identify which alternative stock assessment model configurations relative to the reference m...
Article
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 close-loop simulations to assess the performance of different management procedures in data limited situations, managers in most developing countries are still demandi...
Article
Model-based stock assessments form a key component of the management advice for fish and invertebrate stocks worldwide. It is important for such assessments to be peer-reviewed and to pass scientific scrutiny before they can be used to inform management decision making. While it is desirable for management decisions to be based on quantitative asse...
Article
Full-text available
Performance evaluation of data-limited, length-based methods is instrumental in determining and quantifying their accuracy under various scenarios and in providing guidance about model applicability and limitations. We conducted a simulation-estimation analysis to compare the performance of four length-based stock assessment methods: length-based T...
Article
Renewed interest in the estimation of spatial and temporal variation in fish traits, such as body size, is a result of computing advances and the development of spatially-explicit management frameworks. However, many attempts to quantify spatial structure or the distribution of traits utilize a priori approaches, which involve pre-designated geogra...
Presentation
Full-text available
Oral presentation to Theme N "Data Limited tool an Management" in ICES Annual Science Conference 2019, Gothenburg, Sweden at 9-12 september
Article
Data-limited methods for managing stocks have expanded greatly over the last decade due to the necessity of quantitatively assessing exploited populations with limited information. A special category of such approaches is based on stock reduction analysis. These "catch-only" methods provide a way to handle low data availability, but also require as...
Conference Paper
Full-text available
The Chilean sea urchin is one of the most economic, social and ecological important benthic invertebrate fishery in the world. Different data types exist to evaluate this population such as catch, an index of abundance and length composition from the catch. However, these data are not informative and for this reason the stock remains unassessed. In...
Article
Analysing how fish populations and their ecological communities respond to perturbations such as fishing and environmental variation is crucial to fisheries science. Researchers often predict fish population dynamics using species‐level life‐history parameters that are treated as fixed over time, while ignoring the impact of intraspecific variation...
Conference Paper
Full-text available
The Chilean sea urchin is one of the most economic, social and ecological important benthic invertebrate fishery in the world. Different data types exist to evaluate this population such as catch, an index of abundance and length composition from the catch. However, these data are not informative and for this reason the stock remains unassessed. In...
Article
Large scombrids, commercial tuna species, are regularly assessed and managed. However, most of the small scombrids, many mackerels and bonitos, lack accurate catch data to implement traditional stock assessments despite their economic importance in many small-scale fisheries. In this study, we analysed different approaches using length composition...
Article
The majority of the world's fisheries, by number, are data‐poor/limited, and there is a growing body of literature pertaining to approaches to estimate data‐limited stock status. There are at least two drivers for assessing the status of data‐limited fisheries. The first is to try to understand and report on the global or regional status of fisheri...
Article
A standardized bottom trawl survey monitored the recovery of canary rockfishes Sebastes pinniger along the US west coast. We examined catch-per-unit-effort (CPUE), distribution and life history parameters for canary rockfishes, an important groundfish that severely limited other US west coast fisheries from 2000 to 2015 due to their overfished stat...
Article
Several rockfish stocks off the U.S. west coast are below target biomass and are managed under rebuilding plans that severely limit the allowable harvest. Limited harvest, however, reduces the opportunity to collect fishery-dependent data, which are the primary source of information on changes in abundance for species poorly sampled by fishery-inde...
Article
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...
Article
Full-text available
A Bayesian approach to parameter estimation in fisheries stock assessment is often preferred over maximum likelihood estimates, and fisheries management guidelines also sometimes specify that one or the other paradigm be used. However, important issues remain unresolved for the Bayesian approach to stock assessment despite over 25 years of research...
Article
Stock assessments based on the integrated paradigm often include an underlying stock-recruitment relationship. This, along with estimates of fishery selectivity and biological parameters, allows the biomass and fishing mortality associated with Maximum Sustainable Yield (BMSY and FMSY respectively) to be calculated. However, the estimates of these...
Article
Full-text available
Scientists and resource managers need to know life history parameters (e.g., average mortality rate, individual growth rate, maximum length or mass, and timing of maturity) to understand and respond to risks to natural populations and ecosystems. For over one-hundred years, scientists have identified “life history invariants” (LHI) representing pai...
Article
Marine fish populations exist in a complex environment, with oceanographic and fisheries factors affecting their dynamics. It has been shown that life history characteristics of marine fish vary in space and time. We examined spatial variability in growth of eight groundfish species in the Northeast Pacific Ocean to identify shared spatial patterns...
Conference Paper
Data-limited methods were used to estimate the total allowable catch of gillnet fisheries for the scalloped hammerhead shark (Sphyrna lewini) in the southeast-south of Brazil. Catch trend Surplus Production MSY (SPMSY), average historical catch (AvC), and constant catch management procedure of Geromont and Butterworth (CC1 and CC4) were applied to...
Conference Paper
Full-text available
Data-limited methods were used to estimate the total allowable catch of gillnet fisheries for the scalloped hammerhead shark (Sphyrna lewini) in the southeast-south of Brazil. Catch trend Surplus Production MSY (SPMSY), average historical catch (AvC), and constant catch management procedure of Geromont and Butterworth (CC1 and CC4) were applied to...
Article
Full-text available
Fisheries scientists are increasingly concerned about changes in vital rates caused by environmental change and fishing impacts. Demographic parameters representing individual growth, maturity, mortality, and recruitment have previously been documented to change over decadal time scales. However, there has been relatively little comparison regardin...
Article
Full-text available
Worldwide, fishery managers strive to maintain fish stocks at or above levels that produce maximum sustainable yields, and to rebuild overexploited stocks that can no longer support such yields. In the United States, rebuilding overexploited stocks is a contentious issue, where most stocks are mandated to rebuild in as short a time as possible, and...
Conference Paper
The application of stock assessments to fisheries management on the west coast of the United States has been greatly enhanced by the ongoing development of Stock Synthesis, a flexible statistical catch-at-age framework. While this framework has been enhanced to incorporate more data and parameters, recent develops have also demonstrated its use in...
Article
Full-text available
The majority of global fish stocks lack adequate data to evaluate stock status using conventional stock assessment methods. This poses a challenge for the sustainable management of these stocks. Recent requirements to set scientifically based catch limits in several countries, and growing consumer demand for sustainably managed fish have spurred an...
Article
Full-text available
Legislative changes in the United States and elsewhere now require scientific advice on catch limits for data-poor fisheries. The family of stock reduction analysis (SRA) models is widely used to calculate sustainable harvest levels given a time series of harvest data. SRA works by solving the catch equation given an assumed value for spawning biom...
Article
Full-text available
Life history parameters of fish stocks are central to ecological research and management, including the fields of macro-ecology, fisheries science, and ecosystem modeling. The need for such information has led to several life history databases being developed to support and disseminate this information publicly. However, there has been little indep...
Article
Full-text available
Single-species life history parameters are central to ecological research and management, including the fields of macro-ecology, fisheries science, and ecosystem modeling. However, there has been little independent evaluation of the precision and accuracy of the life history values in global and publicly available databases. We therefore develop a...
Article
Full-text available
Bycatch and resultant discard mortality are issues of global concern. The groundfish demersal trawl fishery on the west coast of the United States is a multispecies fishery with significant catch of target and nontarget species. These catches are of particular concern in regard to species that have previously been declared overfished and are curren...
Article
Full-text available
Fisheries bycatch threatens populations of marine megafauna such as marine mammals, turtles, seabirds, sharks and rays, but fisheries impacts on non-target populations are often difficult to assess due to factors such as data limitation, poorly defined management objectives and lack of quantitative bycatch reduction targets. Limit reference points...
Article
Meta-analysis has been an integral tool for fisheries researchers since the late 1990s. However, there remain few guidelines for the design, implementation or interpretation of meta-analyses in the field of fisheries. Here, we provide the necessary background for readers, authors and reviewers, including a brief history of the use of meta-analysis...
Article
Stock Synthesis (SS) is a likelihood-based statistical catch-at-age modeling environment allowing multiple data sources to be used to characterize population dynamics through time. While it is typically applied in data-rich circumstances, its suitability in data-limited situations is investigated in this work. Two “Simple Stock Synthesis” (SSS) app...
Article
Full-text available
Surplus production represents the processes that affect sustainable fishery harvest and is central to the ecology and management of marine fishes. Taxonomy and life history influence the ratio of spawning biomass at maximum sustainable yield to average unfished spawning biomass (SBMSY/SB0), and estimating this ratio for individual stocks is notorio...
Article
Full-text available
Increasingly, multispecies interactions are being considered by US management councils during decision making, which highlights the need for identification of fish assemblages across varying spatial and temporal resolutions. On the US West Coast, previous groundfish assemblage analyses have focused either on particular species groups (i.e. Sebastes...
Article
Full-text available
Multiple lines of evidence suggest that changes in the marine climate in the eastern Bering Sea are leading to numerical and distributional shifts in fish populations that may affect the balance of predator-prey relationships. A rapidly increasing arrowtooth flounder Atheresthes stomias population has prompted concern about the growing threat of ar...
Article
Full-text available
The Magnuson–Stevens Fishery Conservation and Management Act (MSA) requires active management of all stocks at risk of overfishing or otherwise in need of conservation and management. In the Pacific Fishery Management Council groundfish fishery management plan, about two-thirds of the more than 90 managed stocks are currently without traditional as...
Article
Full-text available
A way to explicitly incorporate ageing error into the estimation of von Bertalanffy growth function (VBGF) parameters using a random effects (RE) modeling framework is presented. This RE framework also accounts for the effects of selectivity on growth curve estimation by characterizing the distribution of true ages derived from multiple age reads u...