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Schematic showing multispecies MSY in terms of community risk (CR) and reward. The maximum yield is estimated by simulation from a large number of potential strategies
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The concept of an optimum yield at intermediate levels of fishing (the so called maximum sustainable yield or MSY) has been with us since the 1930s and is now enshrined in legislation as a key objective of fisheries management. The concept seems intuitively reasonable and is readily applicable to a single stock treated in isolation and assuming a c...
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This study has used a qualitative methodology (SWOT Analysis) to identify factors that have either constrained or facilitated the management of artisanal marine fish resources through local management committees in Ghana. The study identified that although community-based fisheries management committees are important for regulating the activities o...
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... Indeed PEW (2023) argues that it can be achieved through the use of more holistic models (multispecies and wider ecosystem) in management strategy evaluation (MSE) , a point also made by Kaplan et al. (2021). This allows the incorporation of multispecies and ecosystem feedback within the decision-making process, helping the stakeholders to visualize and agree upon some of the trade-offs involved (Thorpe, 2019). ...
The current epoch in fisheries science has been driven by continual advances in laboratory techniques and increasingly sophisticated approaches to analysing datasets. We now have the scientific knowledge and tools to proactively identify obstacles to the sustainable management of marine resources. However, in addition to technological advances, there are predicted global environmental changes, each with inherent implications for fisheries. The 2023 symposium of the Fisheries Society of the British Isles called for “open and constructive knowledge exchange between scientists, stakeholders, managers and policymakers” ( https://fsbi.org.uk/symposium-2023/ ), a nexus of collaborative groups best placed to identify issues and solutions. Arguably, the Centre of Environment, Aquaculture and Fisheries Science (Cefas) and their Scientific Advice for Fisheries Management (SAFM) Team sit at the centre of such a network. SAFM regularly engages with managers and stakeholders, undertakes scientific research, provides fisheries advice to the UK government, and are leading experts within the International Council for the Exploration of the Sea (ICES). As such, this paper is an opinion piece, linked to individual authors specialisms, that aims to highlight emerging issues affecting fisheries and suggest where research efforts could be focused that contribute to sustainable fisheries.
... Another interesting development in expanding the concept of MSY from single species to multi-species is the multivariate MSY, which relies on aggregating data from multiple fleets capturing various species simultaneously. One of the most prominent methods of such computation is based on Nash Equilibrium, wherein the stage at which any given species does not get influenced after attaining an optimum, irrespective of the variation in the capture of competing and cohabiting resources (Thorpe, 2019). Such approaches coupled with full extraction and utilisation of prior knowledge of the species being studied would always come in handy while assessing stocks of our subcontinent. ...
This paper explores the possible options for quantitative fishery stock assessment in tropicalwaters and is composed of four layers viz., concepts, methodologies, data and indicators.The concept promotes the fundamental theory that has been popular in research on stockdynamics, including the possibility of combining it with various doses of intrinsicallybiological information, from individual fish to regional stocks. After reviewing the concepts,tools and their evolution, an attempt has also been made to propose a few guidelines as thebest ways to approach stock assessment and formulate input control or output regulationstrategies in the most pragmatic yet scientific manner, thereby ensuring minimal impact onthe fishery, fishers and stocks in the medium term. Keywords:Bayesian approach, Capture fisheries, Fish stockassessment, Models
... It has been widely utilized in mixed fisheries worldwide (Mueter and Megrey, 2006;Guillen et al., 2013), and holds significant potential for application in China, given the prevalent presence of diverse species or stocks that are harvested simultaneously (Sun et al., 2023a). In contrast to the aforementioned single-species Maximum Sustainable Yield (MSY), which is typically determined for an individual species in isolation, serving as management reference points for each group under the HCR scenario, the multi-species MSY strategy involves managing the ecosystem as a whole (Thorpe, 2019). It aims at maximizing total catches, with full consideration of species interactions in ecosystems. ...
... This contrasts with and complements existing approaches (some of which are summarised in Table 3) which may focus more on the characteristics of current states rather than the extent to which any future uses are precluded (literature examples of this are shaded blue in Table 3). Whilst the traditional Maximum Sustainable Yield (MSY) approach (Mesnil, 2012;Thorpe, 2019) for fisheries opts for sustainable patterns of use of marine resources, it does not consider either the ecological impact on the whole ecosystem, or indeed whether any future states are ruled out by the approach, even if it is sustainable as narrowly defined (Rossberg et al., 2017). By way of contrast, still other approaches (an example of which is shaded gold in Table 3) are less Fig. 8. Recovery trajectories for a 2 • C warming scenario with high levels of demersal fishing, showing the point of recovery for a) the standard recovery definition, with 4 years in 10 inside the last decade of the unfished scenario, b) recovery once rates of change fall to less than 10 % of maximum, c) recovery to within 10 % of unfished abundances, d) recovery to within 1 % of unfished abundances. ...
Ecosystem-based management is mandated by international legislation, including the Marine Strategy Framework Directive (MSFD) in the EU. This introduces a requirement for marine environments to achieve "Good Environmental Status" or GES, implying that the ecosystem is in a healthy and biodiverse state which does not limit the management options of future generations. Indicators of GES typically refer to the current or past state; however, an alternative approach that defines GES in terms of being able to recover to the appropriate reference unperturbed state within 30 years if human activities cease has been suggested. In this study we evaluate this "longest recovery timescales" (LRT) approach using the StrathE2E2 "big picture" model, an end-to-end ecosystem model designed to evaluate both top-down and bottom-up effects at an ecosystem level. We ask whether the approach is enough to prevent severe depletion as well as ensuring recovery at some future time. We also ask whether implementation is practical given uncertainties in defining appropriate baselines for recovery, defining what recovery looks like relative to this baseline, and taking account of natural variability. We find that the main issues with implementation of LRT are a) defining the appropriate baseline for recovery in a changing environment, and b) ensuring that there is stakeholder acceptance of any recommended actions in the event that they differ substantially from current policy. Subject to these two issues, we conclude that the LRT method is a valuable addition to management in support of achieving GES alongside existing methods that focus on current or near-future states.
... Maximum Sustainable Yield is the yield obtained by applying the optimal level of effort that can be sustained without negatively impacting the long-term productivity of the stock. It is the maximum yield that can be taken indefinitely from a stock; that is, the maximum harvest that is sustainable in the long term 20 . It is thus the optimal yield of the fishery. ...
To address the issue of overfishing, sustainability and its effect on marine fishers' income, this study was taken up in Mumbai, India. Greater Mumbai was studied at micro level. Primary data on capital costs, operating costs and returns to mechanized fishing were collected. Secondary data on marine fish landings, landings from the trawlers and total effort of trawlers was collected from 2000-2018. The Gompertz-Fox Model was used, and results showed that Maximum Sustainable Yield (MSY) was at 1,04,099 tonnes of fish and effort level corresponding to MSY (E MSY) at 43,363 fishing trips against the current 1,31,118 tonnes and 33,466 trips. Maximum Economic Yield (MEY) was calculated to be 1,03,030 tonnes, while the estimated value of effort (E MEY) was 37,429 trips. Therefore, the current fishing yield was found to be both biologically and economically unsustainable. The study concluded that the catch and income of fishers may be sustainably enhanced by following the MSY and MEY approach. Fishing at MEY will yield increased income in real terms as well as saved catch will ensure minimisation of environmental damage. Reducing the input costs will enable savings on wasteful operational costs, resulting in increased savings, which in other words, is income, since averted loss is income earned.
... One major drawback is their simplistic treatment of mixed fisheries as an accumulation of many single-species fisheries, which can overlook the interconnections between species. This can lead to over optimistic MSY estimates, unreliable reference point estimates, and even biased assessment results (Mace, 2001;Thorpe, 2019;McQuaw and Hilborn, 2020;Howell et al. 2021). Additionally, the reliability of data-limited methods is often questionable compared to data-rich assessments, which can result in greater uncertain in stock status estimates (ICES, 2012;Newman et al. 2015). ...
Mixed fisheries occur when multiple species are caught together and harvested by multiple fleets. The biological and technical interactions in mixed fisheries distinguish them from single-species fisheries, which makes them challenging for their assessment and management. The present knowledge synthesis reviewed pertinent policy documents and academic databases for twenty-three mixed fisheries worldwide; aiming to characterize attributes of mixed fisheries, provide overviews on their assessment and management, assess current research progress, and identify key factors that impact management effectiveness. Mixed fisheries were found to exhibit varying characteristics worldwide, rendering the implementation of universal management solutions unlikely. While mixed fisheries stock assessment and management are mostly based on single-species approaches, additional mixed fisheries considerations were incorporated at various scales, including multispecies, sector-specific, fishery, and ecosystem levels. Ecosystem-wide management considerations were the most significant contributor to improved management performance in terms of conserving stock biomass and preventing overfishing, underscoring the merits of the Ecosystem-based Fisheries Management (EBFM) principle. Mixed fisheries research demonstrated regional and thematic variations, with the most popular topics addressing immediate and practical management concerns, and the less frequently discussed topics offering valuable insights related to climate change and socio-ecological perspectives. The synthesis identified the available management approaches for mixed fisheries from different jurisdictions, yet their diversity highlighted a lack of global consensus on best management practices. Future mixed fisheries will benefit from balancing tradeoffs between ecological and socio-economic needs, implementing EBFM, adopting diverse and harmonized management tools, and prioritizing monitoring efforts.
... This does not mean there will be a wholesale abandonment of current core fisheries resource and ecosystem management concepts. Instead, concepts like Maximum Sustainable Yield will continue to evolve to encompass multispecies sustainability and entire system-level dynamics as they have begun to do (Mace 2001;Thorpe 2019). ...
A common goal among fisheries science professionals, stakeholders, and rights holders is to ensure the persistence and resilience of vibrant fish populations and sustainable, equitable fisheries in diverse aquatic ecosystems, from small headwater streams to offshore pelagic waters. Achieving this goal requires a complex intersection of science and management, and a recognition of the interconnections among people, place, and fish that govern these tightly coupled socioecological and sociotechnical systems. The World Fisheries Congress (WFC) convenes every four years and provides a unique global forum to debate and discuss threats, issues, and opportunities facing fish populations and fisheries. The 2021 WFC meeting, hosted remotely in Adelaide, Australia, marked the 30th year since the first meeting was held in Athens, Greece, and provided an opportunity to reflect on progress made in the past 30 years and provide guidance for the future. We assembled a diverse team of individuals involved with the Adelaide WFC and reflected on the major challenges that faced fish and fisheries over the past 30 years, discussed progress toward overcoming those challenges, and then used themes that emerged during the Congress to identify issues and opportunities to improve sustainability in the world's fisheries for the next 30 years. Key future needs and opportunities identified include: rethinking fisheries management systems and modelling approaches, modernizing and integrating assessment and information systems, being responsive and flexible in addressing persistent and emerging threats to fish and fisheries, mainstreaming the human dimension of fisheries, rethinking governance, policy and compliance, and achieving equity and inclusion in fisheries. We also identified a number of cross-cutting themes including better understanding the role of fish as nutrition in a hungry world, adapting to climate change, embracing transdisciplinarity, respecting Indigenous knowledge systems, thinking ahead with foresight science, and working together across scales. By reflecting on the past and thinking about the future, we aim to provide guidance for achieving our mutual goal of sustaining vibrant fish populations and sustainable fisheries that benefit all. We hope that this prospective thinking can serve as a guide to (i) assess progress towards achieving this lofty goal and (ii) refine our path with input from new and emerging voices and approaches in fisheries science, management, and stewardship.
... Traditional approaches to fisheries management primarily operate from a single-species perspective. However, species are part of the larger ecosystem such that changes in biomass across species-caused by biotic, abiotic, or management actions-could affect species interactions (Hunsicker et al., 2011), fisher behaviour, fishing effort (Fulton et al., 2011), and subsequently, sustainable harvest levels (Ulrich et al., 2002(Ulrich et al., , 2011Thorpe et al., 2017;Thorpe, 2019). It is becoming increasingly clear that single species approaches carried out without consideration of these fishery technical (e.g. more than one species being caught by a fishery, or different fleets catching differing proportions of various species) and biological interactions (e.g. ...
... It is impossible to fish all species simultaneously at their single species target biological reference points (e.g. MSY, MEY) when there are multispecies interactions, either through technical fishery interactions or biological interactions such as competition or predation (Ulrich et al., 2002(Ulrich et al., , 2011Thorpe et al., 2017;Thorpe, 2019). Therefore, multispecies management inherently involves the need to make tradeoffs. ...
... Multispecies models enable an evaluation of the risks (e.g. risk of collapse, biomass <5% unfished biomass) to bycatch species in the ecosystem under different combinations of fishing rates on target species (Thorpe et al., 2017;Thorpe, 2019). One way this can be done is through management strategy evaluations (MSE), where multispecies models can be used as the operating model (e.g. ...
Multispecies models have existed in a fisheries context since at least the 1970s, but despite much exploration, advancement, and consideration of multispecies models, there remain limited examples of their operational use in fishery management. Given that species and fleet interactions are inherently multispecies problems and the push towards ecosystem-based fisheries management, the lack of more regular operational use is both surprising and compelling. We identify impediments hampering the regular operational use of multispecies models and provide recommendations to address those impediments. These recommendations are: (1) engage stakeholders and managers early and often; (2) improve messaging and communication about the various uses of multispecies models; (3) move forward with multispecies management under current authorities while exploring more inclusive governance structures and flexible decision-making frameworks for handling tradeoffs; (4) evaluate when a multispecies modelling approach may be more appropriate; (5) tailor the multispecies model to a clearly defined purpose; (6) develop interdisciplinary solutions to promoting multispecies model applications; (7) make guidelines available for multispecies model review and application; and (8) ensure code and models are well documented and reproducible. These recommendations draw from a global assemblage of subject matter experts who participated in a workshop entitled “Multispecies Modeling Applications in Fisheries Management”.
... MSY is a theoretical management approach, as it is the supposed highest catch of a species that maximizes the economic rent while simultaneously ensuring that the species population is still at a sustainable level [13]. The concept of MSY originated in Schaefer's 1954 paper [28], and has since been widely considered and researched [3,17,19,30,31,32,36,38]. Applying MSY to our bionomic system allows for a conceptually easy comparison to other policies we consider. ...
Sustainable use of biological resources is very important as over-exploitation on a long run may lead to the stock depletion which in turn may threaten biodiversity. The Chesapeake Bay is an extremely complex ecosystem, and sustainable harvesting of its fisheries is very important both for the ecosystem biodiversity and for the economic prosperity of the area. Here we use mathematical modeling to study the population dynamics with harvesting of two very important fish in the Chesapeake Bay, menhaden as a prey and striped bass as a predator. We start by fitting the generalized Lotka-Volterra model to real population data for the two species obtained from the fisheries in the Bay. We derive conditions for the existence of the bio-economic equilibrium and investigate the stability and the resilience of the biological system. We study the maximum sustainable yield, maximum economic yield, and resilience maximizing yield policies and their effects on the fisheries long time sustainability and particularly on the menhaden-bass population dynamics. This study may be used by policy-makers to balance the economic and ecological harvesting goals while managing the populations of Atlantic menhaden and striped bass in the Chesapeake Bay fisheries.
... In this case, fishing selectivity should be flexible enough to spread fishing pressure across a reasonable range of species, rather than being just limited to target species. This balanced harvest approach is highly applicable to complex multispecies, multi-gear fisheries as the traditional single-species MSY are proved unattainable due to the intricate biological and technical interactions (Guillen et al., 2013;Thorpe, 2019;Zhang et al., 2016). It should be noted that balanced harvest is not equivalent to unregulated unselective fishing. ...
... For example, the North Sea demersal fisheries, which catch many species with single-species catch quotas, suffer the 'choke species' issue as species with lower quotas tend to cause the fisheries to close, compromising fishing opportunities for species with ample quotas (Mortensen et al., 2018). Determining the appropriate MSYs at either single-species or multispecies level is tricky and problematic (Thorpe, 2019). Moreover, operationalizing species-aggregated catch limits requires a balance between conserving the vulnerable stock and maximizing total yield. ...
Understanding and managing fishery selectivity to target species and desirable size are instrumental to fisheries management. China, as the world's largest producer of marine capture fisheries, has been widely perceived to possess unselective domestic fisheries. To date, this perception remains largely anecdotal and conjectural, hindering the development of evidence‐based and effective management solutions. Here, we conducted a literature review to examine the magnitude and scale of unselective fisheries in China. By collating and analysing 140 fishery‐level and 807 species‐level records from 66 peer‐reviewed publications from 2010 to 2021, we found that primary target species were absent in 59% of fisheries, while unidentifiable low‐value and juvenile mixed catch were universal. Key commercial taxa were subject to nationwide multi‐gear and multispecies fisheries, each involving an average of 3.33 types of gear and accounting for less than 25% of catch individually. The ‘permissible gears’ defined by the national gear regulatory catalogue were selective over target species and caught negligible by‐products, though they were used less frequently, representing only 24% of catch records. While unselective fishing can provide seafood supplies for China's large population and potentially facilitate balanced harvest, management actions are needed to control the fishing pressure on primary target species and by‐product species. Amid the ongoing fisheries management reform in China, we proposed management recommendations tailored to China's needs and social contexts, including accounting for the trade‐off between socio‐economic and ecological goals, contemplating impacts of unselective fishing when implementing TAC programmes, and strengthening fisheries monitoring to inform management at multiple scales.
