scholarly journals Refining Fisheries Advice With Stock-Specific Ecosystem Information

2021 ◽  
Vol 8 ◽  
Author(s):  
Jacob W. Bentley ◽  
Mathieu G. Lundy ◽  
Daniel Howell ◽  
Steven E. Beggs ◽  
Alida Bundy ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Single Species ◽  
Ecosystem Model ◽  
Irish Sea ◽  
Fishing Mortality ◽  
Standard Assessment ◽  
Stock Assessments ◽  
Current Assessment ◽  
The Irish Sea ◽  
Management Advice

Although frequently suggested as a goal for ecosystem-based fisheries management, incorporating ecosystem information into fisheries stock assessments has proven challenging. The uncertainty of input data, coupled with the structural uncertainty of complex multi-species models, currently makes the use of absolute values from such models contentious for short-term single-species fisheries management advice. Here, we propose a different approach where the standard assessment methodologies can be enhanced using ecosystem model derived information. Using a case study of the Irish Sea, we illustrate how stock-specific ecosystem indicators can be used to set an ecosystem-based fishing mortality reference point (FECO) within the “Pretty Good Yield” ranges for fishing mortality which form the present precautionary approach adopted in Europe by the International Council for the Exploration of the Sea (ICES). We propose that this new target, FECO, can be used to scale fishing mortality down when the ecosystem conditions for the stock are poor and up when conditions are good. This approach provides a streamlined quantitative way of incorporating ecosystem information into catch advice and provides an opportunity to operationalize ecosystem models and empirical indicators, while retaining the integrity of current assessment models and the FMSY-based advice process.

scholarly journals Combining Ecosystem and Single-Species Modeling to Provide Ecosystem-Based Fisheries Management Advice Within Current Management Systems

2021 ◽  
Vol 7 ◽  
Author(s):  
Daniel Howell ◽  
Amy M. Schueller ◽  
Jacob W. Bentley ◽  
Andre Buchheister ◽  
David Chagaris ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Single Species ◽  
Reference Points ◽  
Atlantic Menhaden ◽  
Irish Sea ◽  
Management Systems ◽  
The Irish Sea ◽  
Management Advice ◽  
Ecosystem Based Fisheries Management ◽  
Single Species Model

Although many countries have formally committed to Ecosystem-Based Fisheries Management (EBFM), actual progress toward these goals has been slow. This paper presents two independent case studies that have combined strategic advice from ecosystem modeling with the tactical advice of single-species assessment models to provide practical ecosystem-based management advice. With this approach, stock status, reference points, and initial target F are computed from a single-species model, then an ecosystem model rescales the target F according to ecosystem indicators without crossing pre-calculated single-species precautionary limits. Finally, the single-species model computes the quota advice from the rescaled target F, termed here Feco. Such a methodology incorporates both the detailed population reconstructions of the single-species model and the broader ecosystem perspective from ecosystem-based modeling, and fits into existing management schemes. The advocated method has arisen from independent work on EBFM in two international fisheries management systems: (1) Atlantic menhaden in the United States and (2) the multi species fisheries of the Irish Sea, in the Celtic Seas ecoregion. In the Atlantic menhaden example, the objective was to develop ecological reference points (ERPs) that account for the effect of menhaden harvest on predator populations and the tradeoffs associated with forage fish management. In the Irish Sea, the objective was to account for ecosystem variability when setting quotas for the individual target species. These two exercises were aimed at different management needs, but both arrived at a process of adjusting the target F used within the current single-species management. Although the approach has limitations, it represents a practical step toward EBFM, which can be adapted to a range of ecosystem objectives and applied within current management systems.

scholarly journals Food for thought: pretty good multispecies yield

2016 ◽  
Vol 74 (2) ◽  
pp. 475-486 ◽  
Author(s):  
Anna Rindorf ◽  
Catherine Mary Dichmont ◽  
Phillip S. Levin ◽  
Pamela Mace ◽  
Sean Pascoe ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Social Benefits ◽  
Sustainable Yield ◽  
Average Yield ◽  
Operational Management ◽  
Operating Space ◽  
Management Advice ◽  
Safe Operating

Abstract MSY principles for marine fisheries management reflect a focus on obtaining continued high catches to provide food and livelihoods for humanity, while not compromising ecosystems. However, maintaining healthy stocks to provide the maximum sustainable yield on a single-species basis does not ensure that broader ecosystem, economic, and social objectives are addressed. We investigate how the principles of a “pretty good yield” range of fishing mortalities assumed to provide >95% of the average yield for a single stock can be expanded to a pretty good multispecies yield (PGMY) space and further to pretty good multidimensional yield to accommodate situations where the yield from a stock affects the ecosystem, economic and social benefits, or sustainability. We demonstrate in a European example that PGMY is a practical concept. As PGMY provides a safe operating space for management that adheres to the principles of MSY, it allows the consideration of other aspects to be included in operational management advice in both data-rich and data-limited situations. PGMY furthermore provides a way to integrate advice across stocks, avoiding clearly infeasible management combinations, and thereby hopefully increasing confidence in scientific advice.

scholarly journals Fishers’ knowledge improves the accuracy of food web model predictions

2019 ◽  
Vol 76 (4) ◽  
pp. 897-912 ◽  
Author(s):  
Jacob W Bentley ◽  
Natalia Serpetti ◽  
Clive Fox ◽  
Johanna J Heymans ◽  
David G Reid
Keyword(s):  
Hybrid Model ◽  
Scientific Knowledge ◽  
Fishing Effort ◽  
Irish Sea ◽  
Environmental Drivers ◽  
Global Context ◽  
Hybrid Knowledge ◽  
The Irish Sea ◽  
Management Advice ◽  
Improved Model

Abstract Fisher's knowledge offers a valuable source of information to run parallel to observed data and fill gaps in our scientific knowledge. In this study we demonstrate how fishers' knowledge of historical fishing effort was incorporated into an Ecopath with Ecosim (EwE) model of the Irish Sea to fill the significant gap in scientific knowledge prior to 2003. The Irish Sea model was fitted and results compared using fishing effort time-series based on: (i) scientific knowledge, (ii) fishers' knowledge, (iii) adjusted fishers' knowledge, and (iv) a combination of (i) and (iii), termed “hybrid knowledge.” The hybrid model produced the best overall statistical fit, capturing the biomass trends of commercially important stocks. Importantly, the hybrid model also replicated the increase in landings of groups such as “crabs & lobsters” and “epifauna” which were poorly simulated in scenario (i). Incorporating environmental drivers and adjusting vulnerabilities in the foraging arena further improved model fit, therefore the model shows that both fishing and the environment have historically influenced trends in finfish and shellfish stocks in the Irish Sea. The co-production of knowledge approach used here improved the accuracy of model simulations and may prove fundamental for developing ecosystem-based management advice in a global context.

Using food web model results to inform stock assessment estimates of mortality and production for ecosystem-based fisheries management

2010 ◽  
Vol 67 (9) ◽  
pp. 1490-1506 ◽  
Author(s):  
Sarah K. Gaichas ◽  
Kerim Y. Aydin ◽  
Robert C. Francis
Keyword(s):  
Food Web ◽  
Fisheries Management ◽  
Prey Availability ◽  
Stock Assessment ◽  
Marine Ecosystem ◽  
Single Species ◽  
Balance Model ◽  
Fishing Mortality ◽  
Important Species ◽  
Predation Mortality

Examining food web relationships for commercially important species enhances fisheries management by identifying sources of variability in mortality and production that are not included in standard single-species stock assessments. We use a static mass-balance model to evaluate relationships between species in a large marine ecosystem, the coastal Gulf of Alaska, USA. We focus on food web relationships for four case-study species: Pacific halibut ( Hippoglossus stenolepis ), longnose skate ( Raja rhina ), walleye pollock ( Theragra chalcogramma ), and squids (order Teuthoidea). For each, we present the species’ position within the food web, evaluate fishing mortality relative to predation mortality, and evaluate diet compositions. We find that high trophic level (TL) species, whether commercially valuable (halibut) or incidentally caught (skates), have mortality patterns consistent with single-species assessment assumptions, where fishing mortality dominates natural mortality. However, assessments for commercially valuable (pollock) or incidentally caught (squids) mid-TL species can be enhanced by including food web derived predation information because fishing mortality is small compared with high and variable predation mortality. Finally, we outline food web relationships that suggest how production of species may change with diet composition or prey availability.

scholarly journals Socio-Ecological Outcomes of Single-Species Fisheries Management: The Case of Yellow Perch in Lake Erie

2021 ◽  
Vol 9 ◽  
Author(s):  
Katherine Lee ◽  
Jenny Apriesnig ◽  
Hongyan Zhang
Keyword(s):  
Food Web ◽  
Fisheries Management ◽  
Yellow Perch ◽  
Lake Erie ◽  
Economic Models ◽  
Single Species ◽  
Ecosystem Model ◽  
Economic Losses ◽  
Fish Stock ◽  
Management Units

This manuscript uses seminal models in fisheries economics to assess the ecosystem effects of policy focused on sustainable management of a single fish stock. Economic models representing fishing decisions under open access and two fisheries management schemes are parameterized using data from the four management units in the Lake Erie Yellow Perch (Persus flavenscens) fishery and linked with an end-to-end ecosystem model representative of the lake food web and spatial species interactions. We find that the sustainable harvest rules from single species economic models result in significant changes to biomass of species in planktivorous, omnivorous, and piscivorous groups in the ecosystem model. These impacts can be traced through the food web back to harvest rules implemented in the management units. Most notably, the biomass of several non-target but also commercially harvested fish species are reduced through Yellow Perch fishing. In some cases, the economic losses to coexisting fisheries exceeds benefits gained from implementing the Yellow Perch management scheme. Our results imply that while an ecosystem-based approach to fisheries management requires weighing trade-offs between multiple fisheries, an ex ante understanding of the whole-system consequences of harvest rules can be critical for developing policy that overall enhances ecological and social wellbeing.

scholarly journals A simulation study of the implications of age-reading errors for stock assessment and management advice

2003 ◽  
Vol 60 (2) ◽  
pp. 314-328 ◽  
Author(s):  
Stuart A. Reeves
Keyword(s):  
Stock Assessment ◽  
Age Determination ◽  
General Tendency ◽  
Fishing Mortality ◽  
Absolute Level ◽  
Total Allowable Catch ◽  
Reading Errors ◽  
Stock Assessments ◽  
Management Advice ◽  
Age Reading

Abstract Catch-at-age data are a crucial input to many stock assessments, so errors in age determination could have an adverse effect on the quality of the stock assessment and the scientific advice based on that assessment. The results of simulation studies presented in this study are intended to quantify the effects of age-reading errors on the perception of stock trends and short-term management advice. The study is based on Eastern Baltic cod, in which problems with consistent interpretation of otolith structures result in the catch-at-age data being particularly problematic. The results indicate a clear distinction between the performance of the assessment, and the performance of catch forecasts and advice based on that assessment. The ageing error affected the absolute level of estimates of fishing mortality and spawning stock biomass from stock assessments, although overall trends are similar, and general conclusions about the state of the stock are likely to be broadly correct. Greater problems arose in catch forecasts and advice, for which ageing error led to discrepancies between the required and the effective fishing mortality, and a general tendency for ageing error to lead to advice on Total Allowable Catch that would be too optimistic and, therefore, less effective for stock conservation.

scholarly journals The Use of a Length-Structured Multispecies Model Fitted Directly to Data in Near-Real Time as a Viable Tool for Advice

2021 ◽  
Vol 8 ◽  
Author(s):  
Michael A. Spence ◽  
Paul J. Dolder ◽  
Richard Nash ◽  
Robert B. Thorpe
Keyword(s):  
Real Time ◽  
Single Species ◽  
Turnaround Time ◽  
Data Sources ◽  
Assessment Process ◽  
Irish Sea ◽  
Great Promise ◽  
Natural Mortality ◽  
Multispecies Model ◽  
The Irish Sea

Fish communities are multispecies assemblages, so ideally multispecies models should be used directly for assessing this resource. However, progress in this direction has been slow, partly because these models are often more complex and take longer to fit, rendering them too slow to demonstrate near-real-time utility, and thus creating a perception that they are opaque to stakeholders. In this study we implemented a multispecies assessment for the Irish Sea, fitting a model of eight key stocks directly to catch and survey data. Two novel features of our approach allowed the multispecies model to be fitted within a few hours. Firstly, by using size-based theory and life-history invariants to specify many of the required properties of stocks, we reduced the number of general parameters that needed to be fitted directly to a more manageable 25. Secondly, by using state-of-the-art fitting methods, we found acceptable solutions quickly enough to provide assessments within the timescale of an advisory meeting. The outcomes were compared with the standard single species assessments of the same eight species. Model fits were generally good for either catch or at least one of the surveys, but not for all data sources at the same time, illustrating the challenges of fitting multiple stocks to different data sources simultaneously. Estimates of SSB and F agreed qualitatively with the assessments for most stocks with the exception of whiting. Estimates of natural mortality showed modest year to year variability, suggesting that single species assessments may be appropriate for short term tactical management. This method shows great promise for making multispecies assessments as a complement to existing assessments because of the rapid turnaround time and ability to respond at meetings to the requests of stakeholders. In addition, because these models avoid our current dependence on existing single species models they can be used to provide boundary conditions in natural mortality for standard assessment models and check for internal consistency in the assessment process. Furthermore, they are easily accessible because they are based upon freely available code.

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