共查询到20条相似文献，搜索用时 15 毫秒
1.
Christopher M. Anderson Melissa J. Krigbaum Martin C. Arostegui Megan L. Feddern John Zachary Koehn Peter T. Kuriyama Christina Morrisett Caitlin I. Allen Akselrud Melanie J. Davis Courtney Fiamengo Ava Fuller Qi Lee Katherine N. McElroy Maite Pons Jessica Sanders 《Fish and Fisheries》2019,20(2):268-285
Wild capture fisheries produce 90 million tonnes of food each year and have the potential to provide sustainable livelihoods for nearly 40 million people around the world ( http://www.fao.org/3/a-i5555e.pdf ). After decades of overfishing since industrialization, many global fish stocks have recovered, a change brought about through effective management. We provide a synthetic overview of three approaches that managers use to sustain stocks: regulating catch and fishing mortality, regulating effort and regulating spatial access. Within each of these approaches, we describe common restrictions, how they alter incentives to change fishing behaviour, and the resultant ecological, economic and community‐level outcomes. For each approach, we present prominent case‐studies that illustrate behaviour and the corresponding performance. These case‐studies show that sustaining target stocks requires a hard limit on fishing mortality under most conditions, but that additional measures are required to generate economic benefits. Different systems for allocation allow stakeholder communities to strike a locally acceptable balance between profitability and employment. 相似文献
2.
Ashley M. Fowler Natalie A. Dowling Jeremy M. Lyle Josep Alós Leif E. Anderson Steven J. Cooke Andy J. Danylchuk Keno Ferter Heath Folpp Clifford Hutt Kieran Hyder Daniel K. Lew Michael B. Lowry Tim P. Lynch Nicholas Meadows Estanis Mugerza Kjell Nedreaas Domingos Garrone-Neto Faith A. Ochwada-Doyle Warren Potts David Records Scott Steinback Harry V. Strehlow Sean R. Tracey Michael D. Travis Jun-ichi Tsuboi Jon Helge Vølstad Rowan C. Chick 《Fish and Fisheries》2023,24(6):1003-1019
Recreational fishing (RF) is a large yet undervalued component of fisheries globally. While progress has been made in monitoring, assessing, and managing the sector in isolation, integration of RF into the management of multi-sector fisheries has been limited, particularly relative to the commercial sector. This marginalises recreational fishers and reduces the likelihood of achieving the sector's objectives and, more broadly, achieving fisheries sustainability. We examined the nature and extent of RF inclusion in harvest strategies (HSs) for marine fisheries across 15 regions in 11 nations to define the gap in inclusion that has developed between sectors. We focused on high-income nations with a high level of RF governance and used a questionnaire to elicit expert knowledge on HSs due to the paucity of published documents. In total, 339 HSs were considered. We found that RF inclusion in HSs was more similar to the small-scale sector (i.e., artisanal, cultural, or subsistence) than the commercial sector, with explicit operational objectives, data collection, performance indicators, reference points, and management controls lacking in many regions. Where specified, RF objectives focused on sustainability, economic value and catch allocation rather than directly relating to the recreational fishing experience. Conflicts with other sectors included competition with the commercial sector for limited resources, highlighting the importance of equitable resource allocation policies alongside HSs. We propose that RF be explicitly incorporated into HSs to ensure fisheries are ecologically, economically, and socially sustainable, and we recommend that fisheries organisations urgently review HSs for marine fisheries with a recreational component to close the harvest strategy gap among sectors. 相似文献
3.
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
4.
Christopher J Brown Glenn Althor Benjamin S Halpern Md Sayed Iftekhar Carissa J Klein Simon Linke Elizabeth C Pryde Steven Schilizzi James E M Watson Becky Twohey Hugh P Possingham 《Fish and Fisheries》2018,19(1):107-116
Almost all environmental management comes at an economic cost that may not be borne equitably by all stakeholders. Here, we investigate how heterogeneity in catch and profits among fishers influences the trade‐off among the triple‐bottom‐line objectives of recovering a fish population, maximizing its economic value and distributing restrictions equitably across fishers. As a case‐study, we examine management reform of an ecologically and economically important coral reef fishery operating within the Great Barrier Reef Marine Park. Using a simulation model, we find that total profitability of the fishing industry is 40% lower if recovery plans are equitable when compared to the most economically efficient plan. However, efficient recovery plans were typically highly inequitable because they required some fishers to cease fishing. Equity was defined according to different norms, and the efficiency loss was greatest when catch losses were shared equally across fishers rather than in proportion to their historical catch. We then varied key social, economic and biological parameters to identify cases when equity and efficient recovery would trade‐off most strongly. Recovery plans could be both efficient and equitable when heterogeneity in fisher's catches and individual catch efficiencies was lower. If fishers were homogenous then equitable plans could have maximal economic efficiency. These results emphasize the importance of considering heterogeneity in individual fishers when designing recovery plans. Recovery plans that are inequitable may often fail to gain stakeholder support, so in fisheries with high heterogeneity we should temper our expectations for marked increases in profits. 相似文献
5.
Roberto Licandeo Santiago de la Puente Villy Christensen Ray Hilborn Carl Walters 《Fish and Fisheries》2023,24(4):544-566
We present a novel adaptation of the classic discrete delay-difference model, a continuous delay-differential model (cDDM), which can adequately represent population dynamics of stocks that turn over rapidly and continuously over time (e.g., small pelagic fish, small tunas, and shrimps). We used the Northern-Central Peruvian anchoveta stock (Engraulis ringens, Engraulidae) as a case study for implementing the cDDM and conducted a management strategy evaluation (MSE) through stochastic optimization in policy space (SOPS). Our results showed that cDDM integrated with SOPS efficiently searches optimum and near-optimum harvest control rules (HCR) and is an alternative to pre-setting arbitrary HCRs as in traditional MSE. The cDDM showed comparable stock biomass and recruitment estimate reconstructions to more complex stock assessment models described for anchoveta. We concluded that the anchoveta stock is sustainably managed and is an example of adaptive fisheries management under high ocean-climate variability and uncertainty. Contrary to fishery textbooks, the anchoveta's collapse was not entirely due to the 1972 El Niño (EN) but a recruitment failure preceding EN. Our reconstructions revealed that low recruitment (or recruitment failure) could still occur at high stock biomass. Anchoveta's stock biomass is larger than pre-collapse, likely due to favourable environmental conditions (a cooling trend) and management, despite more frequent and stronger EN events. SOPS quickly revealed that harvest strategies with large base biomass (>5 mmt) lead to higher interannual stock variability and would not produce substantial increases in long-term yield. Alternative HCRs with lower base biomass, while adjusting for productivity regimes, have similar long-term yields without affecting the long-term average stock. 相似文献
6.
Alistair Becker Matthew D. Taylor Heath Folpp Michael B. Lowry 《Fish and Fisheries》2018,19(4):740-752
Fisheries enhancement initiatives are a potentially useful tool for managers to supplement traditional approaches. Habitat‐based enhancements often deploy artificial reefs with the aim to increase the available structure to augment local production, yet current assessment approaches make it difficult to assess whether these reefs achieve pre‐deployment goals. This makes it hard for managers to determine whether artificial reefs could improve their fishery outputs, potentially leading to missed opportunities and reduced production. We reviewed 270 research articles to determine whether existing monitoring studies identify whether artificial reefs meet their pre‐deployment goals, thereby providing some evidence of their suitability for certain fisheries. We found only 62% of these studies clearly articulated the original goals of the reef. Goals were qualitative, and most studies were conducted over insufficient time frames to allow for ecological communities to stabilize and mature. It is therefore difficult to determine the success or failure of many artificial reefs in addressing the management issues for which they were deployed. In the light of these findings, we think the setting of explicit quantitative goals (which may be biological, social or economic), and monitoring the performance of reefs against these goals, could stimulate the broader application of artificial reefs in fisheries management strategies. Such an approach has been successfully adopted in aquaculture‐based fisheries enhancement, and we explain how current evaluation methods such as harvest strategies can be easily adapted to quantitatively monitor artificial reef performance. 相似文献
7.
The principles of Ecologically Sustainable Development and Ecosystem Based Fisheries Management require that fisheries be managed for social as well as environmental and economic objectives. Comprehensive assessments of the success of fisheries in achieving all three objectives are, however, rare. There are three main barriers to achieving integrated assessments of fisheries. Firstly, disciplinary divides can be considered “too hard” to bridge with inherent conflicts between the predominately empirical and deductive traditions of economics and biophysical sciences and the inductive and interpretative approach of much of the social sciences. Secondly, understanding of the social pillar of sustainability is less well developed. And finally, in‐depth analysis of the social aspects of sustainability often involves qualitative analysis and there are practical difficulties in integrating this with largely quantitative economic and ecological assessments. This article explores the social well‐being approach as a framework for an integrated evaluation of the social and economic benefits that communities in New South Wales, Australia, receive from professional fish harvesting. Using a review of existing literature and qualitative interviews with more than 160 people associated with the fishing industry the project was able to identify seven key domains of community well‐being to which the industry contributes. Identification of these domains provided a framework through which industry contributions could be further explored, through quantitative surveys and economic analysis. This framework enabled successful integration of social and economic, and both qualitative and quantitative information in a manner that enabled a comprehensive assessment of the value of the fishery. 相似文献
8.
We present a framework for evaluating fisheries management plans comprehensively, both rebuilding plans and others. The framework includes a first rapid appraisal of the likelihood that the plan will result in management meeting its objectives, and guides subsequent quantitative analyses of potential weaknesses in the proposed plan. The framework includes four steps: (i) evaluating if a set of management objectives, if achieved, would result in a sustainable fishery, (ii) using qualitative analysis of a bio‐economic model to evaluate whether the set of stock management tactics might be capable of achieving the specified fisheries objectives, (iii) using empirical criteria derived from the literature to evaluate if other management measures in the plan related to the ecological, social or economic context of the fishery actually contribute to sustainability, and (iv) carrying out quantitative simulations to compare alternative implementation options. Generally, several management measures have to be combined to increase stock size without sacrificing the economic benefits to the fishers remaining in the fishery. We demonstrate application of the framework for evaluating the stock rebuilding plan for plaice (Pleuronectes platessa) and sole (Solea solea) in the North Sea and, the management measures currently in place for the roundnose grenadier (Coryphaenoides rupestris) stock exploited to the west of the British Isles. 相似文献
9.
André E Punt Doug S Butterworth Carryn L de Moor José A A De Oliveira Malcolm Haddon 《Fish and Fisheries》2016,17(2):303-334
Management strategy evaluation (MSE) involves using simulation to compare the relative effectiveness for achieving management objectives of different combinations of data collection schemes, methods of analysis and subsequent processes leading to management actions. MSE can be used to identify a ‘best’ management strategy among a set of candidate strategies, or to determine how well an existing strategy performs. The ability of MSE to facilitate fisheries management achieving its aims depends on how well uncertainty is represented, and how effectively the results of simulations are summarized and presented to the decision‐makers. Key challenges for effective use of MSE therefore include characterizing objectives and uncertainty, assigning plausibility ranks to the trials considered, and working with decision‐makers to interpret and implement the results of the MSE. This paper explores how MSEs are conducted and characterizes current ‘best practice’ guidelines, while also indicating whether and how these best practices were applied to two case‐studies: the Bering–Chukchi–Beaufort Seas bowhead whales (Balaena mysticetus; Balaenidae) and the northern subpopulation of Pacific sardine (Sardinops sagax caerulea; Clupeidae). 相似文献
10.
Fisheries-independent survey data are vital to stock assessment and management because they provide reliable information on stock status. Although survey data have been increasingly recognised for their contributions to fisheries management, they have often not been adequately used to provide quantitative management recommendations for China's fisheries that are subject to limited data. In the present study, a framework was proposed to integrate two types of survey-based management procedures (MPs) into China's fisheries management: the slope-based MP and the target-based MP. Specifically, the former generates fishing effort limits based on the trend in recent years’ abundance index, while the latter sets effort limits based on a static abundance index target. To test the performance of these MPs, management strategy evaluation was performed using a simulated fishery based on the small yellow croaker, Larimichthys polyactis (Bleeker) in Haizhou Bay, China. The sensitivity of MPs was investigated under different algorithm parameterisations and historical exploitation levels. Additionally, their robustness was evaluated in the face of survey uncertainty and changes in recruitment success. Both MPs could effectively improve the stock status compared with the status quo management when appropriately parameterised regardless of exploitation history. The target-based MP was more robust to survey uncertainty than the slope-based MP. Non-stationary changes in recruitment success strongly impaired the management effects, while using recruitment-specific instead of the age-aggregated abundance index could slightly enhance their performance. This work indicates that survey-based MPs can address the current challenges in China's fisheries management and reinforce the status quo management practice with limited data and highlights the potential risks. 相似文献
11.
Richard M Hillary Ann L Preece Campbell R Davies Hiroyuki Kurota Osamu Sakai Tomoyuki Itoh Ana M Parma Doug S Butterworth James Ianelli Trevor A Branch 《Fish and Fisheries》2016,17(2):469-482
There is considerable international concern and scientific debate about the current state and future of tuna stocks worldwide and the capacity of Regional Fisheries Management Organisations to manage the associated fisheries effectively. In some cases, this concern has extended to predictions of imminent collapse with minimal chances of recovery, even under a commercial catch moratorium. As a viable alternative to a full fishery closure, the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) has adopted a scientifically tested, adaptive rebuilding strategy for the depleted southern bluefin tuna (Thunnus maccoyii) stock. The management procedure (MP) adopted involves a harvest control rule that fully specifies the total allowable catch as a function of key indicators of stock status, adjusting future harvest levels every three years so as to meet the rebuilding targets agreed by CCSBT. It was chosen from a subset of candidate MPs selected following extensive simulation testing. This involved first selecting a wide range of plausible scenarios for stock status and input data, ranging from pessimistic to optimistic, against which the alternative candidate MPs were tested to ensure that they were robust to important uncertainties. This is the first time that a comprehensively evaluated MP has been adopted for an internationally managed tuna stock. Both the process and the outcomes have broad applicability to other internationally managed stocks. 相似文献
12.
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
13.
Quang C. Huynh Adrian R. Hordyk Robyn E. Forrest Clay E. Porch Sean C. Anderson Thomas R. Carruthers 《Fish and Fisheries》2020,21(3):663-679
Stock assessments are often used to provide management advice, such as a total allowable catch (TAC), to fishery managers. Many stocks are not assessed annually, and the TAC from the previous assessment is often maintained in years between assessments. We developed two interim management procedures (MPs) that update the estimate of current vulnerable biomass from a surveyed index of abundance to adjust the TAC from a previous assessment. These MPs differ in how they handle uncertainty in observed indices. Using closed‐loop simulation, we evaluated the two interim MPs (with 10‐ and 5‐year assessment intervals) against several “status quo” approaches: (1) an annual assessment, and (2) a stock assessment every 5 or 10 years with (a) fixed TACs or (b) projections between assessments. We evaluated performance across three life‐history types and six operating model scenarios. The interim MPs performed similarly to annual assessments in terms of trends in biomass and yield, regardless of the assessment interval of the interim MPs. The interim MPs often produced more yield than the Fixed TAC MP with 10‐year assessment intervals, for example, in depleted scenarios. The Fixed TAC MP performed more similarly to interim MPs when the assessment interval for the Fixed TAC MP was decreased to five years. The interim MPs can also perform well when circumstances arise that are not accounted for in the Projection MP. Our results show that interim MPs should be considered for infrequently assessed stocks or rebuilding stocks, and highlight potential cost savings of interim MPs over annual assessments. 相似文献
14.
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
15.
Thomas R. Carruthers Quang C. Huynh Adrian R. Hordyk David Newman Anthony D. M. Smith Keith J. Sainsbury Kevin Stokes Alexander Morison David Agnew Ana Parma Ignacio Sobrino Catherine Longo 《Fish and Fisheries》2023,24(2):279-296
Fisheries managers are in need of quantitative tools to inform decisions regarding selection of robust management practices, prioritising research gaps and stocks to focus on, particularly where there are limited resources or data. To support these decisions, the use of Management Strategy Evaluation (MSE), that is, closed loop simulation-testing of management procedures, is widely regarded as best practice. However, applying MSE is time- and computationally intensive, and requires highly skilled expertise and processes for stakeholder input and peer review. For data- and capacity-limited fisheries, MSE may be particularly challenging to implement. Yet, these are the contexts where it is most critical to test assumptions, evaluate the implications of all sources of uncertainty and identify the most informative data sources. To facilitate wider use of MSE, the Method Evaluation and Risk Assessment (MERA) framework was developed as an accessible online interface, with quick processing time, focused on generic data-limited management procedures, but allowing progression to tailored and more data-rich methods. The framework links a quantitative questionnaire and data input standard to a flexible operating model with optional customisation via command line access to the back-end open-source R libraries. Here, we illustrate a case study application of MERA for the bocinegro (Pagrus pagrus, Sparidae) fishery in the Gulf of Cadiz, where in conjunction with fishery stakeholders, a custom management procedure was developed and tested and key research gaps and data collection priorities were identified. We discuss implications for wider use of MSE in various contexts, including eco-certification and fishery improvement projects. 相似文献
16.
Simon H. Fischer José A. A. De Oliveira John D. Mumford Laurence T. Kell 《Fish and Fisheries》2023,24(2):231-247
Fisheries management needs to ensure that resources are exploited sustainably, and the risk of depletion is at an acceptable level. However, often uncertainty about resource dynamics exists, and data availability may differ substantially between fish stocks. This situation can be addressed through tiered systems, where tiers represent different data limitations, and tier-specific stock assessment methods are defined, aiming for risk equivalence across tiers. As case studies, we selected stocks of European plaice, Atlantic cod and Atlantic herring, where advice is provided by the International Council for the Exploration of the Sea (ICES). We conducted a closed-loop simulation to compare risk equivalence between the data-rich ICES MSY rule, based on a quantitative stock assessment, and the revised data-limited empirical management procedures of the ICES advice framework. The simulations indicated that the data-limited approaches were precautionary and did not lead to a higher risk of depletion than the data-rich approach. Although the catch based on generic data-limited approaches was lower, stock-specific optimisation improved management performance with catch levels comparable with the data-rich approach. Furthermore, the simulation indicated the ICES MSY rule can fail to meet management objectives due to increased depletion risk when management reference points are set suboptimally. We conclude that the recent revisions of the ICES system explicitly account for risk equivalence for data-limited fisheries management and are a major step forward. Finally, we advocate further consideration of simple empirical management procedures irrespective of data limitations due to their ability to meet fisheries management objectives with greater simplicity. 相似文献
17.
Catherine M Dichmont André E Punt Natalie Dowling José A A De Oliveira Lorne R Little Miriana Sporcic Elizabeth Fulton Rebecca Gorton Neil Klaer Malcolm Haddon David C Smith 《Fish and Fisheries》2016,17(3):731-747
There can be substantial differences in data quality and quantity among fished species. Consequently, the quality and type of assessments can also vary substantially. However, all species, especially those that are targeted, need to be managed. Several jurisdictions have developed hierarchical tier systems that categorize stocks based on, for example, the data available for assessment purposes and/or the extent to which quantities on which management advice is based can be estimated. Four case‐studies (Australia's Southern and Eastern Scalefish and Shark Fishery, the USA west coast groundfishery, the USA Alaskan crab fishery and EU fisheries) are used to contrast the types of hierarchical tier systems available, and to assess the extent to which each system constrains risk to be equivalent among the tiers (termed risk equivalency). Only the Australian system explicitly aims to achieve risk equivalency. However, this intent has not been fully operationalized. Our review reveals that best practice is not to define tiers simply on data availability, but also on what the assessments based on those data are capable of estimating. In addition, clearly differentiating the quantification of uncertainty from how decision‐makers wish to address that uncertainty would simplify justification of buffers (the gap between the assessment‐produced target catch or effort and the final management decision that accounts for uncertainty and risk). Risk equivalency can be achieved using management strategy evaluation to select the values for control variables, which determine the buffer given the uncertainty associated with the assessment. 相似文献
18.
- Human‐caused mortality threatens many marine turtle populations worldwide, with fisheries interactions being a primary cause for population declines. National and international management of fisheries interactions with marine turtles are rarely tied to turtle population biology. Quantitative tools tied to population‐based objectives can provide insight into the effectiveness and urgency of bycatch mitigation.
- A management approach is proposed based on a bycatch control rule called Reproductive Value Loss Limit (RVLL), generalized from the Potential Biological Removal management model for marine mammal populations. For RVLL, population size is scaled by reproductive value to account for strongly age‐structured population dynamics and age‐dependent fisheries mortality rates in marine turtle populations.
- RVLL is an estimate of maximum sustainable mortality for a population, calculated from estimates of maximum population growth rate, total reproductive value in the population, and an uncertainty factor. RVLL estimates correspond to specified management goals and risk tolerances. For demonstration, simultaneous goals of maintaining populations above the maximum net productivity level (analogous to the population size that produces maximum sustainable yield) and preventing a decrease in adults are assumed, both with 95% probability. A management‐strategy‐evaluation‐like process was used to explore parameterization of the RVLL equation for robust performance over a range of plausible life history characteristics and uncertainties in abundance and bycatch mortality estimates for marine turtle populations.
- The RVLL‐based management approach presented here proved robust to several important sources of uncertainty and to violation of several key underlying assumptions, and can be adapted to account for important sources of bias. The architecture presented, including tailored management strategy evaluation, provides a useful basis for further development of reference‐point‐based management of human‐added mortality in populations that experience large changes with age in reproductive value and human‐caused mortality rates, as is the case for marine turtles.
19.
There is international recognition for greater inclusion of recreational fisheries catch data in species, fisheries and ecosystem assessments. Recreational charter fisheries provide important social services and contribute to total species catches. This study compares and validates industry logbook catch and effort data (1,357 trips) against observer data (154 trips) across six ports in a recreational charter fishery in eastern Australia. The mean numbers of clients and fishing effort (hours) per trip varied inconsistently between data sources and among ports. Logbooks did not adequately report released catches, and the mean number of species retained per trip was consistently underestimated in logbooks compared to observer data. For both data sources, catch rates of total individuals and key species displayed similar trends across different units of effort; catch per hour, client, client/hour and trip. The mean catch rates of total individuals and most key species, except those retained for bait, were similar across data sources, as were estimates of total fleet harvests. The length compositions of retained catches of some key species displayed truncation of larger organisms in the observer data whereas other species did not. Despite the shortcomings of the logbook data, future fishery and species monitoring strategies could include industry and observer data sources. 相似文献
20.
- Social‐ecological system sustainability depends in part upon the fit between ecosystems and institutions.
- In 2014, the local community on Easter Island started a bottom‐up process to improve marine resources conservation and management.
- Local stakeholders formed a working group that has regular meetings and goals, such as creating a sea council and some basic action plans, thus initiating a local governance transformation process.
- A participatory process was conducted together with a local organization that led the marine conservation issues on the island to define the factors that could favour and/or undermine the formation of the sea council. Also, the stakeholders that must be present in such a sea council were identified.
- Twelve factors that could facilitate or hinder the implementation of a sea council were identified. The lack of representativeness of public institutions is a major challenge.
- Public institutions are designed to ensure compliance with central government strategies, but the decisions do not represent the worldview of islanders.
- The results showed the potential value of conducting a participatory process to identify the key issues that could hinder or favour a desired governance transformation process. The participatory process also highlighted governance mismatches that are important to consider in attempts to pursue more effective fishery governance on Easter Island, and other Island communities.
- Centralized governance systems do not respond rapidly to locally observed social and ecological dynamics. By contrast, a local decision‐making system based on traditional laws and local governance can more rapidly respond to observed changes.
- The participatory process presented here holds the potential to support local people in their planning and coordination for marine conservation and management in order to optimize bottom‐up change processes involving multiple stakeholders with different interests, values and levels of power.