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1.
The increasing need to account for the many factors that influence fish population dynamics, particularly those external to the population, has led to repeated calls for an ecosystem approach to fisheries management (EAFM). Yet systematically and clearly addressing these factors, and hence implementing EAFM, has suffered from a lack of clear operational guidance. Here, we propose 13 main factors (shift in location, migration route or timing, overfishing (three types), decrease in physiology, increase in predation, increase in competition, decrease in prey availability, increase in disease or parasites and a decline in habitat quality or habitat quantity) that can negatively influence fish populations via mechanisms readily observable in ~20 population features. Using these features as part of a diagnostic framework, we develop flow charts that link probable mechanism(s) underlying population change to the most judicious management actions. We then apply the framework for example case studies that have well‐known and documented population dynamics. To our knowledge, this is the first attempt to provide a clearly defined matrix of all the probable responses to the most common factors influencing fish populations, and to examine possible diagnostics simultaneously, comparatively and relatively in an attempt to elucidate the most probable mechanisms responsible. The framework we propose aims to operationalize EAFM, thereby not only better diagnosing factors influencing fish populations, but also suggesting the most appropriate management interventions, and ultimately leading to improved fisheries. We assert the framework proposed should result in both better use of limited analytical and observational resources and more tailored and effective management actions. 相似文献
2.
考虑到生态系统状态对渔业的重要影响,渔业生态系统方法(Ecosystem Approach to Fisheries,EAF)把对生态的关注加入渔业管理框架中,并以生态系统管理和渔业管理2个理论为基础,扩展了传统渔业管理的框架:以生态系统健康与人类福利的依存关系为基础,关注多物种管理,均衡生态、人文和制度3个维度的目标,实现渔业的可持续发展。本研究介绍了EAF的由来、定义、基本原则以及功能要素,概述了EAF的实践基础和模型构建的技术路径,对比了EAF与EBFM的异同。虽然EAF的理论和实践仍处于完善和发展阶段,但确为渔业管理的发展方向,介绍EAF对促进我国渔业可持续发展具有重要意义。 相似文献
3.
Mette Skern‐Mauritzen Geir Ottersen Nils Olav Handegard Geir Huse Gjert E Dingsør Nils C Stenseth Olav S Kjesbu 《Fish and Fisheries》2016,17(1):165-175
Fish stock productivity, and thereby sensitivity to harvesting, depends on physical (e.g. ocean climate) and biological (e.g. prey availability, competition and predation) processes in the ecosystem. The combined impacts of such ecosystem processes and fisheries have lead to stock collapses across the world. While traditional fisheries management focuses on harvest rates and stock biomass, incorporating the impacts of such ecosystem processes are one of the main pillars of the ecosystem approach to fisheries management (EAFM). Although EAFM has been formally adopted widely since the 1990s, little is currently known to what extent ecosystem drivers of fish stock productivity are actually implemented in fisheries management. Based on worldwide review of more than 1200 marine fish stocks, we found that such ecosystem drivers were implemented in the tactical management of only 24 stocks. Most of these cases were in the North Atlantic and north‐east Pacific, where the scientific support is strong. However, the diversity of ecosystem drivers implemented, and in the approaches taken, suggests that implementation is largely a bottom‐up process driven by a few dedicated experts. Our results demonstrate that tactical fisheries management is still predominantly single‐species oriented taking little account of ecosystem processes, implicitly ignoring that fish stock production is dependent on the physical and biological conditions of the ecosystem. Thus, while the ecosystem approach is highlighted in policy, key aspects of it tend yet not to be implemented in actual fisheries management. 相似文献
4.
Report card on ecosystem‐based fisheries management in tuna regional fisheries management organizations
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Maria José Juan‐Jordá Hilario Murua Haritz Arrizabalaga Nicholas K Dulvy Victor Restrepo 《Fish and Fisheries》2018,19(2):321-339
International instruments of fisheries governance have set the core principles for the management of highly migratory fishes. We evaluated the progress of tuna Regional Fisheries Management Organizations (tRFMOs) in implementing the ecological component of ecosystem‐based fisheries management (EBFM). We first developed a best case tRFMO for EBFM implementation. Second, we developed criteria to evaluate progress in applying EBFM against this best case tRFMO. We assessed progress of the following four ecological components: target species, bycatch species, ecosystem properties and trophic relationships, and habitats. We found that many of the elements necessary for an operational EBFM are already present, yet they have been implemented in an ad hoc way, without a long‐term vision and a formalized plan. Overall, tRFMOs have made considerable progress monitoring the impacts of fisheries on target species, moderate progress for bycatch species, and little progress for ecosystem properties and trophic relationships and habitats. The tRFMOs appear to be halfway towards implementing the ecological component of EBFM, yet it is clear that the “low‐hanging fruit” has been plucked and the more difficult, but surmountable, issues remain, notably the sustainable management of bycatch. All tRFMOs share the same challenge of developing a formal mechanism to better integrate ecosystem science and advice into management decisions. We hope to further discussion across the tRFMOs to inform the development of operational EBFM plans. 相似文献
5.
Tyler D Eddy Heike K Lotze Elizabeth A Fulton Marta Coll Cameron H Ainsworth Júlio Neves de Araújo Catherine M Bulman Alida Bundy Villy Christensen John C Field Neil A Gribble Mejs Hasan Steve Mackinson Howard Townsend 《Fish and Fisheries》2017,18(1):40-53
Since the 1950s, invertebrate fisheries catches have rapidly expanded globally to more than 10 million tonnes annually, with twice as many target species, and are now significant contributors to global seafood provision, export, trade and local livelihoods. Invertebrates play important and diverse functional roles in marine ecosystems, yet the ecosystem effects of their exploitation are poorly understood. Using 12 ecosystem models distributed worldwide, we analysed the trade‐offs of various invertebrate fisheries and their ecosystem effects as well as ecological indicators. Although less recognized for their contributions to marine food webs, our results show that the magnitude of trophic impacts of invertebrates on other species of commercial and conservation interest is comparable with those of forage fish. Generally, cephalopods showed the strongest ecosystem effects and were characterized by a strong top‐down predatory role. Lobster, and to a lesser extent, crabs, shrimp and prawns, also showed strong ecosystem effects, but at lower trophic levels. Benthic invertebrates, including epifauna and infauna, also showed considerable ecosystem effects, but with strong bottom‐up characteristics. In contrast, urchins, bivalves, and gastropods showed generally lower ecosystem effects in our simulations. Invertebrates also strongly contributed to benthic–pelagic coupling, with exploitation of benthic invertebrates impacting pelagic fishes and vice versa. Finally, on average, invertebrates produced maximum sustainable yield at lower levels of depletion (~45%) than forage fish (~65%), highlighting the need for management targets that avoid negative consequences for target species and marine ecosystems as a whole. 相似文献
6.
Ecosystem‐based fishery management requires considering the effects of actions on social, natural and economic systems. These considerations are important for forage fish fisheries, because these species provide ecosystem services as a key prey in food webs and support valuable commercial fisheries. Forage fish stocks fluctuate naturally, and fishing may make these fluctuations more pronounced, yet harvest strategies intended to ameliorate these effects might adversely affect fisheries and communities. Here, we evaluate trade‐offs among a diverse suite of management objectives by simulating outcomes from several harvest strategies on forage fish species. We demonstrate that some trade‐offs (like those between catches and minimizing collapse length) were universal among forage species and could not be eliminated by the use of different control rules. We also demonstrate that trade‐offs vary among forage fish species, with strong trade‐offs between stable, high catches and high‐biomass periods (“bonanzas”) for menhaden‐ and anchovy‐like fish, and counterintuitive trade‐offs for sardine‐like fish between shorter collapses and longer bonanzas. We find that harvest strategies designed to maintain stability in catches will result in more severe collapses. Finally, we show that the ability of assessments to detect rapid changes in population status greatly affects control rule performance and the degree and type of trade‐offs, increasing the risk and severity of collapses and reducing catches. Together, these results demonstrate that while default harvest strategies are useful in data‐poor situations, management strategy evaluations that are tailored to specific forage fish may better balance trade‐offs. 相似文献
7.
Ane T Laugen Georg H Engelhard Rebecca Whitlock Robert Arlinghaus Dorothy J Dankel Erin S Dunlop Anne M Eikeset Katja Enberg Christian Jørgensen Shuichi Matsumura Sébastien Nusslé Davnah Urbach Loїc Baulier David S Boukal Bruno Ernande Fiona D Johnston Fabian Mollet Heidi Pardoe Nina O Therkildsen Silva Uusi‐Heikkilä Anssi Vainikka Mikko Heino Adriaan D Rijnsdorp Ulf Dieckmann 《Fish and Fisheries》2014,15(1):65-96
Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries‐induced evolution (FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life‐history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment (EvoIA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. EvoIA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries. 相似文献
8.
Jeremy S Collie Louis W Botsford Alan Hastings Isaac C Kaplan John L Largier Patricia A Livingston Éva Plagányi Kenneth A Rose Brian K Wells Francisco E Werner 《Fish and Fisheries》2016,17(1):101-125
The advent of an ecosystem‐based approach dramatically expanded the scope of fisheries management, creating a critical need for new kinds of data and quantitative approaches that could be integrated into the management system. Ecosystem models are needed to codify the relationships among drivers, pressures and resulting states, and to quantify the trade‐offs between conflicting objectives. Incorporating ecosystem considerations requires moving from the single‐species models used in stock assessments, to more complex models that include species interactions, environmental drivers and human consequences. With this increasing model complexity, model fit can improve, but parameter uncertainty increases. At intermediate levels of complexity, there is a ‘sweet spot’ at which the uncertainty in policy indicators is at a minimum. Finding the sweet spot in models requires compromises: for example, to include additional component species, the models of each species have in some cases been simplified from age‐structured to logistic or bioenergetic models. In this paper, we illuminate the characteristics, capabilities and short‐comings of the various modelling approaches being proposed for ecosystem‐based fisheries management. We identify key ecosystem needs in fisheries management and indicate which types of models can meet these needs. Ecosystem models have been playing strategic roles by providing an ecosystem context for single‐species management decisions. However, conventional stock assessments are being increasingly challenged by changing natural mortality rates and environmentally driven changes in productivity that are observed in many fish stocks. Thus, there is a need for more tactical ecosystem models that can respond dynamically to changing ecological and environmental conditions. 相似文献
9.
A performance assessment was conducted of regional fisheries management organizations’ (RFMOs’) bycatch governance, one element of an ecosystem approach to fisheries management. Obtaining a mean score of 25%, with a 64% CV, collectively the RFMOs have large governance deficits. Individually, there has been mixed progress, with some RFMOs having made substantial progress for some governance elements. There has been nominal progress in gradually transitioning to ecosystem‐based fisheries management: controls largely do not account for broad or multispecies effects of fishing, and cross‐sectoral marine spatial planning is limited. Regional observers collect half of minimum information needed to assess the efficacy of bycatch measures. Over two‐thirds of RFMO‐managed fisheries lack regional observer coverage. International exchange of observers occurs in one‐third of programmes. There is no open access to research‐grade regional observer data. Ecological risk assessments focus on effects of bycatch removals on vulnerable species groups and effects of fishing on vulnerable benthic marine ecosystems. RFMOs largely do not assess or manage cryptic, generally undetectable sources of fishing mortality. Binding measures address about one‐third of bycatch problems. Eighty per cent of measures lack explicit performance standards against which to assess efficacy. Measures are piecemeal, developed without considering potential conflicts across vulnerable groups. RFMOs employ 60% of surveillance methods required to assess compliance. A lack of transparency and limited reporting of inspection effort, identified infractions, enforcement actions and outcomes further limits the ability to assess compliance. Augmented harmonization could help to fill identified deficits. 相似文献
10.
While there has been a growing concern for the adverse ecological impacts of fishing, progress on incorporating these into operational fisheries management has been slow. Many fisheries management organizations have addressed the problem of overharvesting and over‐capitalization first. In this domain, the question of access regulation has gained growing recognition as a key dimension of fisheries sustainability, leading to recommendation and progressive implementation of rights‐based systems, in particular Individual Transferrable Quotas (ITQs). While adjustments in fishing capacity resulting from the implementation of these systems may entail a reduction in some unwanted ecosystem impacts of fishing, it is also recognized that they will not be sufficient to achieve the ecological outcomes increasingly demanded by the global community. There is thus a need to examine the possibilities for a common management framework for dealing with both over‐capitalization of fisheries and adverse ecological effects of fishing. In this paper, we examine the feasibility of incorporating greater ecosystem goods and services into ITQ policy instruments initially designed with a narrow focus on commercial target species. We consider the advantages and limitations of alternative approaches in this respect and identify some of the practical issues associated with the different alternatives, in particular the underpinning knowledge requirements. We argue that given the need for increasingly streamlined management processes, further investigation into practical ways forward in this domain is crucial if management of fisheries is to achieve economic efficiency while fully encompassing the ecologically sustainable development objectives of ecosystem‐based fisheries management. 相似文献
11.
Mark T. Gibbs 《Fish and Fisheries》2009,10(4):470-474
Recent articles in high‐profile journals advocating the widespread establishment of economic rights‐based approaches for managing fisheries has re‐kindled the debate over the efficacy of incentive‐based vs. regulatory‐based management approaches. Inspection of these works, written from the particular perspectives of economics, fisheries biology, or marine ecology, reveals that advocates of rights‐based regimes such as Individual Transferrable Quotas are sometimes recommending these policy instruments for quite different reasons. Hence, the advantageous attributes of rights‐based approaches from the perspective of one discipline may be quite different when seen from the perspective of another discipline. This is of concern as it exposes a tendency for particular disciplines to consider only the advantages of rights‐based approaches, such as establishing a harvest cap, but to implicitly discount the disadvantages such as less attention being paid to critical ecological and ecosystem issues. 相似文献
12.
Fishing impact and environmental status in European seas: a diagnosis from stock assessments and ecosystem indicators
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Didier Gascuel Marta Coll Clive Fox Sylvie Guénette Jérome Guitton Andrew Kenny Leyla Knittweis J Rasmus Nielsen Gerjan Piet Tiit Raid Morgane Travers‐Trolet Samuel Shephard 《Fish and Fisheries》2016,17(1):31-55
Stock‐based and ecosystem‐based indicators are used to provide a new diagnosis of the fishing impact and environmental status of European seas. In the seven European marine ecosystems covering the Baltic and the North‐east Atlantic, (i) trends in landings since 1950 were examined; (ii) syntheses of the status and trends in fish stocks were consolidated at the ecosystem level; and (iii) trends in ecosystem indicators based on landings and surveys were analysed. We show that yields began to decrease everywhere (except in the Baltic) from the mid‐1970s, as a result of the over‐exploitation of some major stocks. Fishermen adapted by increasing fishing effort and exploiting a wider part of the ecosystems. This was insufficient to compensate for the decrease in abundance of many stocks, and total landings have halved over the last 30 years. The highest fishing impact took place in the late 1990s, with a clear decrease in stock‐based and ecosystem indicators. In particular, trophic‐based indicators exhibited a continuous decreasing trend in almost all ecosystems. Over the past decade, a decrease in fishing pressure has been observed, the mean fishing mortality rate of assessed stocks being almost halved in all the considered ecosystems, but no clear recovery in the biomass and ecosystem indicators is yet apparent. In addition, the mean recruitment index was shown to decrease by around 50% in all ecosystems (except the Baltic). We conclude that building this kind of diagnosis is a key step on the path to implementing an ecosystem approach to fisheries management. 相似文献
13.
The concept of ecosystem‐based fisheries management (EBFM) has been subjected to debate since it was introduced in the late 1990s. The development of the concept seems to follow two separate but simultaneous trajectories of increased popularity but also sustained critique. This paper offers an analysis of potential mechanisms behind these disparate trajectories by drawing on a theoretical framework from science and technology studies (STS) centred around "black box" and actor‐network theory. To support our analysis, we perform an exploratory literature review of how the EBFM concept has been used in a selection of high impact fisheries research papers. We find that the popularity of EBFM does not guarantee its integrity, usefulness or analytical insight, but also that persistent critique of how the concept is used seems to be driving some change. We think that a continued trajectory of increased understanding, contextualization and discernibility of EBFM can help overcome the considerable ambiguity associated with the concept and make it increasingly useful to fisheries management. This means moving away from routine use of the term towards a practicable and tangible approach to improve fisheries sustainability. 相似文献
14.
In the Abrolhos Bank (Southwest Atlantic), multidimensional indicators were used in sustainability assessments of data‐poor reef fisheries. Potential impacts, risks and stocks vulnerabilities were evaluated based on biological, environmental, social and economic aspects by combining both adapted productivity and susceptibility analysis (PSA) and scale intensity consequence analysis (SICA). Data were obtained from local surveys with stakeholders and experts and from literature. A value chain map revealed final consumers at many locations and middleman presence. Vulnerability to overexploitation ranged from low (Cephalopholis fulva (L.), Lutjanus synagris (L.) and Ocyurus chrysurus (Bloch)) to moderate (Lutjanus jocu (Bloch & Schneider), Epinephelus morio (Val.) and Mycteroperca bonaci Poey). While moderate consequences of the catches were observed to C. fulva, major consequences were identified to the other five stocks. The main threat to coral reef habitats was found to be mining wastes. Poor governance may constrain fisheries sustainability in the region, while the empowerment of fishers in both governance and post‐harvest processes should enhance it. 相似文献
15.
A new role for MSY in single-species and ecosystem approaches to fisheries stock assessment and management 总被引:8,自引:0,他引:8
Mace 《Fish and Fisheries》2001,2(1):2-32
In 1977, Peter Larkin published his now‐famous paper, ‘An epitaph for the concept of maximum sustained yield’. Larkin criticized the concept of single‐species maximum sustained yield (MSY) for many reasons, including the possibility that it may not guard against recruitment failure, and the impossibility of maximising sustainable yields for all species simultaneously. However, in recent years, there has been a fundamental change in the perception of the fishing mortality associated with MSY (FMSY) as a limit to be avoided rather than a target that can routinely be exceeded. The concept of FMSY as a limit is embodied in several United Nations Food and Agriculture Organization (FAO) agreements and guidelines, and has now been incorporated into the US Magnuson–Stevens Fishery Conservation and Management Act. As a result, the United States now requires the development of overfishing definitions based on biological reference points that treat the FMSY as a limit reference point and must also define a lower limit on biomass below which rebuilding plans with strict time horizons must be developed. This represents a major paradigm shift from the previously mandated (but often unachieved) objective to simply maintain fishing mortalities at levels below those associated with recruitment overfishing. In many cases, it requires substantial reductions in current fishing mortality levels. Therefore, the necessity of the new paradigm is continually questioned. This paper draws on examples from several fisheries, but specifically focuses on the recent US experience illustrating the practical difficulties of reducing fishing mortality to levels below those corresponding to MSY. However, several studies suggest that even more substantial reductions in fishing mortality may be necessary if ecosystem considerations, such as multispecies interactions, maintenance of biodiversity and genetic diversity, and reduction of bycatch and waste, are taken into account. The pros and cons of moving beyond single‐species assessment and management are discussed. A US plan for improving stock assessments indicates that even a ‘basic’ objective such as ‘adequate baseline monitoring of all managed species’ may be extremely costly. Thus, the suggestion of Larkin (1983, 1997) that the costs of research and management should not exceed 10–20% of the landed value of the catch may preclude comprehensive ecosystem management. More importantly, neither single‐species nor ecosystem‐based fisheries management is likely to improve appreciably unless levels of fishing capacity are aligned with resource productivity, as is currently being promoted by FAO and several individual nations. 相似文献
16.
Ellen K Pikitch Konstantine J Rountos Timothy E Essington Christine Santora Daniel Pauly Reg Watson Ussif R Sumaila P Dee Boersma Ian L Boyd David O Conover Philippe Cury Selina S Heppell Edward D Houde Marc Mangel Éva Plagányi Keith Sainsbury Robert S Steneck Tess M Geers Natasha Gownaris Stephan B Munch 《Fish and Fisheries》2014,15(1):43-64
Forage fish play a pivotal role in marine ecosystems and economies worldwide by sustaining many predators and fisheries directly and indirectly. We estimate global forage fish contributions to marine ecosystems through a synthesis of 72 published Ecopath models from around the world. Three distinct contributions of forage fish were examined: (i) the ecological support service of forage fish to predators in marine ecosystems, (ii) the total catch and value of forage fisheries and (iii) the support service of forage fish to the catch and value of other commercially targeted predators. Forage fish use and value varied and exhibited patterns across latitudes and ecosystem types. Forage fish supported many kinds of predators, including fish, seabirds, marine mammals and squid. Overall, forage fish contribute a total of about $16.9 billion USD to global fisheries values annually, i.e. 20% of the global ex‐vessel catch values of all marine fisheries combined. While the global catch value of forage fisheries was $5.6 billion, fisheries supported by forage fish were more than twice as valuable ($11.3 billion). These estimates provide important information for evaluating the trade‐offs of various uses of forage fish across ecosystem types, latitudes and globally. We did not estimate a monetary value for supportive contributions of forage fish to recreational fisheries or to uses unrelated to fisheries, and thus the estimates of economic value reported herein understate the global value of forage fishes. 相似文献
17.
Steven W Purcell Annie Mercier Chantal Conand Jean‐François Hamel M Verónica Toral‐Granda Alessandro Lovatelli Sven Uthicke 《Fish and Fisheries》2013,14(1):34-59
Worldwide, most sea cucumber fisheries are ineffectively managed, leading to declining stocks and potentially eroding the resilience of fisheries. We analyse trends in catches, fishery status, fishing participation and regulatory measures among 77 sea cucumber fisheries through data from recent fishery reports and fishery managers. Critical gaps in fisheries biology knowledge of even commonly targeted species undermine the expected success of management strategies. Most tropical fisheries are small‐scale, older and typified by numerous (>8) species, whereas temperate fisheries are often emerging, mono‐specific and industrialized. Fisher participation data indicated about 3 million sea cucumber fishers worldwide. Fisher participation rates were significantly related to the average annual yield. permanova analysis showed that over‐exploited and depleted fisheries employed different sets of measures than fisheries with healthier stocks, and a non‐metric multidimensional scaling ordination illustrated that a broad set of regulatory measures typified sustainable fisheries. SIMPER and regression tree analyses identified that the dissimilarity was most related to enforcement capacity, number of species harvested, fleet (vessel) controls, limited entry controls and rotational closures. The national Human Development Index was significantly lower in countries with over‐exploited and depleted fisheries. Where possible, managers should limit the number of fishers and vessel size and establish short lists of permissible commercial species in multispecies fisheries. Our findings emphasize an imperative to support the enforcement capacity in low‐income countries, in which risk of biodiversity loss is exceptionally high. Solutions for greater resilience of sea cucumber stocks must be embedded within those for poverty reduction and alternative livelihood options. 相似文献
18.
19.
- 1. The coral reefs across the international border between Kenya and Tanzania, where historical differences in government policy and socio‐economic conditions created two different management systems, were examined: a large permanent closed area and a collaborative fisheries management project that used gear management and small voluntarily and temporary closed areas, respectively. The diversity and ecology of the reefs in these two management systems were compared spanning a seven‐year period to evaluate the effectiveness of the management and to assess the ecological response to a large‐scale water‐temperature anomaly in 1998.
- 2. Comparisons of rates of predation on sea urchins and of herbivory, using a seagrass assay, were made along with measures of benthic cover and fish abundance and diversity.
- 3. The collaborative fisheries management system was successful in increasing fish stocks, reducing erect algae, and maintaining ecological diversity and stability across the thermal anomaly. This management system, however, was not successful in protecting the expected full biodiversity of fish, predation rates on sea urchins, or the sensitive, branching coral species. Management of the fishery also increased fish stocks in the adjacent, large, permanently closed area, compared to Kenyan parks without this management.
- 4. The large, permanently closed area in the other system maintained high diversity, high predation rates on sea urchins and high herbivory rates, which maintained erect algae abundance and diversity at low levels. The temperature anomaly was destructive to a number of the dominant delicate branching coral species, but overall coral cover and diversity were maintained, although dominance switched from branching Porites spp. to Seriatopora spp. over this period. The large closed area system protected the undisturbed ecology of these reefs and associated ecological processes, and the full diversity of fish and coral, including sensitive species such as branching corals and slow‐growing fish.
- 5. Collaborative fisheries and large permanent closed area management have different attributes that, when combined, should achieve the multiple purposes of sustainable fisheries, ecosystem functions and protection of fishing‐sensitive species.
20.
Tobias K. Mildenberger Casper W. Berg Alexandros Kokkalis Adrian R. Hordyk Chantel Wetzel Nis S. Jacobsen Andr E. Punt J. Rasmus Nielsen 《Fish and Fisheries》2022,23(1):73-92
The precautionary approach to fisheries management advocates for risk-averse management strategies that include biological reference points and account for scientific uncertainty (i.e. process, model and observation uncertainty). In this regard, two approaches have been recommended: (a) biomass reference points to safeguard against low stock biomass, and (b) uncertainty buffers that reduce the catch limit as a function of the scientific uncertainty. This study compares the effectiveness of these two precautionary approaches in recovering over-exploited fish stocks. We evaluate the performance of more than 80 harvest control rules (HCRs) within a stochastic management strategy evaluation (MSE) framework for three stocks with contrasting life-history parameters and under various levels of scientific uncertainty. The results show that both approaches reduce the risk of overfishing at the expense of expected yield. This risk-yield trade-off strongly depends on the HCRs, life-history parameters of the species, as well as the level of the scientific uncertainty. Nevertheless, some combinations of biomass threshold and limit reference points as well as uncertainty buffers lead to a more favourable risk-yield trade-off than other rules. This study elucidates the multiple factors affecting the effectiveness of management strategies and highlights key features of HCRs for precautionary fisheries management. 相似文献