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1.
The use of ITQ management in multi-species fisheries has been the subject of much debate and the complexities and difficulties of managing multi-species fisheries are well known. A major problem is that the species mix in fishery catches may not necessarily match the mix in combined TACs or in quota holdings. While a number of solutions have been proposed or implemented to improve transferability of quota and other incentives to reduce over-quota fishing and discarding, it is surprising that there has been little focus on TAC-setting itself and coordinating this across multiple species/stocks as a means of dealing with some of these issues. In this paper, data were analysed from the trawl sector of the Australian Southern and Eastern Scalefish and Shark Fishery to determine the relationship between primary species and companion species and the implications this has for TAC setting. The primary species is the species being considered when setting an individual species TAC. The companion species are ones that should also be considered when setting the TAC of the primary species, because a considerable proportion of the primary species catch is taken as a companion species non-target catch. The target species in each fishing operation was determined and was used to characterize recent multi-species catch data into primary and companion components. This approach provides an empirical means to examine the impact of individual species TAC decisions across all of the quota species in a fishery. 相似文献
2.
《Journal of Sea Research》2007,57(2-3):114-125
Many flatfish species are caught in mixed demersal trawl fisheries and managed by Total Allowable Catch (TAC). Despite decades of fisheries management, several major stocks are severely depleted. Using the Common Fisheries Policy (CFP) as an example, the failure of mixed-fisheries management is analysed by focussing on: the management system; the role of science; the role of managers and politicians; the response of fisheries to management. Failure of the CFP management could be ascribed to: incorrect management advice owing to bias in stock assessments; the tendency of politicians to set the TAC well above the recommended level; and non-compliance of the fisheries with the management regulations. We conclude that TAC management, although apparently successful in some single-species fisheries, inevitably leads to unsustainable exploitation of stocks caught in mixed demersal fisheries as it promotes discarding of over-quota catch and misreporting of catches, thereby corrupting the basis of the scientific advice and increasing the risk of stock collapse. This failure in mixed demersal fisheries has resulted in the loss of credibility of both scientists and managers, and has undermined the support of fishermen for management regulations. An approach is developed to convert the TAC system into a system that controls the total allowable effort (TAE). The approach takes account of the differences in catch efficiency between fleets as well as seasonal changes in the distribution of the target species and can also be applied in the recovery plans for rebuilding specific components of the demersal fish community, such as plaice, cod and hake. 相似文献
3.
基于北斗船位数据的渔业信息解译与应用研究——以中国毛虾限额捕捞管理为例 总被引：1，自引：0，他引：1
2020年6月15日—7月15日,我国首次中国毛虾(Acetes chinensis)限额捕捞试点于江苏连云港实施。本研究提取62艘毛虾网船在限额捕捞期间的421700条北斗船位数据经纬度、航速、航向等信息,运用缓冲区叠加分析法、DBSCAN密度聚类算法、平均中心算法、核密度估计以及数据库查询对捕捞努力量等管控要素进行分析研究。结果显示,所有毛虾网船累计作业239个航次、1942个网次,捕捞过程分为航行、抛锚布网、等待渔获、收渔获、停航等5个状态,中国毛虾捕捞状态船位点呈直线分布,总捕捞时长为4413.73h,82.4%的单网次捕捞时长为1.5—3.5h,各网次捕捞产量呈现多核心空间分布模式,总捕捞努力量为108106343 m~2·h,计算62艘的捕捞总产量值约为2328 t,比上报产量高12.6%;本文通过北斗船位数据解译和提取捕捞努力量以计算中国毛虾捕捞产量及资源空间分布情况,有效应用于中国毛虾限额捕捞,为解决我国单品种限额捕捞难点积累了宝贵经验。 相似文献
4.
Emerging fisheries and changes in fishery practices are not always readily apparent, nor are their impacts on non-target species such as seabirds, sea turtles, and marine mammals. Data from several different sources led managers to discover high rates of sea turtle bycatch in an inshore large-mesh gillnet fishery in North Carolina, USA, particularly the emerging deep-water gillnet fishery. This paper reviews the history of how increased numbers of observed stranded sea turtles in 1999 led to the discovery that turtles were becoming entangled in the large-mesh gillnet fishery in Pamlico Sound, North Carolina. It also demonstrates how a variety of data sets from fisheries observers, aerial surveys, and fisheries statistics programs contributed to shaping management of the large-mesh gillnet fishery in Pamlico Sound to decrease turtle bycatch and now point towards the need of additional assessment of gillnet bycatch in other parts of North Carolina. Finally, potential approaches are discussed for a more timely detection of future fishery conflicts and development of a plan to reduce otherwise inevitable bycatch and disruptions to fishing effort. 相似文献
5.
This study examined the use of Individual Transferable Quotas (ITQs) to effectively manage fishing impacts on all ecosystem components, as required under Ecosystem Based Fisheries Management (EBFM) principles. A consequence of changing from input controls to output-based (catch) management is that the control of the regulating authority tends to be reduced, which may affect the outcomes for ecosystem management. This study reviewed the use of input controls across six fishing methods in 18 ITQ fisheries, which have been independently accredited as ecologically sustainable by the Marine Stewardship Council (12 fisheries) or under Australian environmental legislation for Wildlife Trade Operation (six fisheries). Input controls were retained across a range of ITQ fisheries, with non-selective fisheries such as trawl, gillnet and line employing more input controls than selective fisheries such as purse-seine, pot/trap and dredge. Further case-studies confirmed the widespread and recent use of input controls (spatial and temporal closures) with the aim of managing ecosystem impacts of fishing. The retention of input controls, particularly closures affects the security (quality of title) characteristic of the fishing use right and the theoretical ability of fishers to manage their right for their future benefit. The security characteristic is weakened by closures through loss of access, which undermines industry trust and incentive for long-term decision making. By reducing the security of ITQs, individual fisher incentives and behaviour may separate from societal objectives for sustainability, which was one of the foremost reasons for introducing ITQ management. 相似文献
6.
《Marine Policy》2016
Effective species management requires good knowledge on vessel dynamics, either at a stock basis or through the establishment of multiannual management plans as advisable under the new European Common Fisheries Policy (CFP). Achieving such knowledge on Portuguese multi-gear fisheries is challenging given the large number of species caught and the different management measures applied to potential target species. The latter ranges from no input or output controls to output controls based on individual vessel quotas (IVQ). To provide accurate regional knowledge to the CFP, the dynamics of vessels involved in the trammel net fishery targeting anglerfish (Lophius spp.) was characterised based on onboard sampling data and logbook reports. The selected vessels were very dynamic, and were found to target other species such as hake (Merluccius merluccius), John Dory (Zeus faber) and octopus (Octopus vulgaris). Anglerfish landing trends can be explained by changes in abundance, quota availability and shifts/changes in fishing effort. Overall, the dynamics of these vessels varied with area of exploitation, IVQ value and anglerfish total allowable catch (TAC). These results show the influence of different management systems in the dynamics of vessels and the advantage of an IVQ management system, where fishers can spatially and temporally allocate effort. Results also highlight a fishing effort shift towards unregulated species in face of IVQ or TAC restrictions. 相似文献
7.
《Marine Policy》2016
Catch shares, where annual catch limits are divided among individuals, communities or cooperatives, are a commonly used fisheries management strategy to increase profits and reduce overcapitalization. Usually these quota shares can be sold or leased, which is theorized to allow for greater utilization of fleet-wide quota. However, this catch-quota balancing may not be achieved in multispecies trawl fisheries where it is difficult to selectively target valuable species while avoiding overfished species. Two similar catch-share-managed, multispecies trawl fisheries were compared to evaluate whether catch shares lead to catch-quota balancing. The U.S. West Coast Groundfish fishery has several species with low total allowable catches (TACs) while the Canadian British Columbia Trawl fishery has comparatively higher TACs. Results indicate that the West Coast fishery had a statistically significant decrease in catch-quota ratios from 0.41 in the three years before catch shares to 0.29 in the three years after catch shares. In contrast, the BC fishery experience no statistically significant change in fishery-wide average catch-quota ratios, which were 0.70 in the three years before and 0.62 in the three years after catch shares. In the West Coast fishery, the risk of exceeding quotas for some species may be so high that fishers are unable to achieve high degrees of catch-quota balancing and instead focus on species that can be easily selected with changes in fishing behavior. Multispecies fisheries management has direct tradeoffs between maximizing yield and achieving conservation goals, and these results may highlight the tradeoff between rebuilding overfished species by reducing TACs, and the achievement of catch-quota balancing. 相似文献
8.
This paper reviews the socio-economic and ecological context of Fijian reef fisheries. This review is deemed necessary because improved understanding of the state and trends of Fiji's coral reef fisheries on a national level is required for designing an effective management plan for Fiji's inshore reef fisheries. The most important point that emerges from our review is that despite numerous studies of Fiji's reef fisheries, the current status of reef-associated fisheries at the national level is still uncertain due, mainly, to the lack of dependable data on the subsistence fisheries. This in turn leads to uncertainty about how the continuation of fishing, in particular, fishing focused on target species for the coral reef resources trade, will affect fishing communities and the ecosystem. 相似文献
9.
《Marine Policy》2016
With the development of the ecosystem approach to fisheries, improving fishing selectivity has increasingly been put forward as an objective for management. The aim of this paper is to clarify the limits of fishing selectivity and its use in fisheries management. Fishing selectivity would be better apprehended if restricted to the catching process only, not to the utilisation that is made of the catch once onboard, which falls under catch utilisation. Confusion would be further limited if fishing selectivity is restricted to the fishing operation scale, while exploitation pattern, i.e. the distribution of fishing mortality at the population or community level, applies to larger scales. Fishing selectively is minimizing bycatch – catching primarily the fishing trip targets. Since the ecological consequences of maximising the target catch relative to bycatch remain unknown at integrated scales, fishing selectivity cannot be used as an objective in itself. However, its small scale, high manageability and good understanding make it a convenient instrument to reach management objectives at large scales. Selectivity can serve to manage what is extracted from the ecosystem and thus what can be used, and/or to manage what is left in the ecosystem and how fishing impacts it. Different factors affect fishing selectivity, catch utilisation and exploitation patterns, some of them are manageable and thus can be used to move towards these objectives. Management tools are diverse, but need to be integrated to meet large-scale objectives. The complexity of dealing with large scales incurs a need to develop the available knowledge on exploitation patterns and catch utilisation to be able to adequately manage and monitor progress toward selectivity-related objectives. 相似文献
10.
P Thoya S Pérez-Jorge GM Okemwa H Mwamlavya A Tuda N Wambiji 《African Journal of Marine Science》2020,42(1):23-33
Ringnet fishing began in the early 20th century and is practised worldwide, mainly to target nearshore pelagic species. The method was introduced to Kenya’s coastal waters by migrant fishers from Tanzania. However, the impacts of this fishing gear remain poorly assessed. We assessed the spatial distribution of ringnet fishing effort and its possible effects on ecosystem components, such as coral reefs, marine megafauna and marine protected areas, on the south coast of Kenya. We tracked 89 ringnet fishing trips made from December 2015 to January 2016 and used spatial multicriteria analysis to determine hotspots of possible environmental risks. The results showed that habitat type and bathymetric profile influenced the spatial distribution of ringnet fishing effort. Mixed seagrass and coral habitats had the highest concentration of the effort. Most of the habitats in the study area were moderately exposed to the impacts of the ringnet fishery. The study identifies high-risk areas that require spatial measures to minimise possible environmental risks of the gear both to habitats and to endangered sea turtles. 相似文献
11.
12.
《Marine Policy》2017
The California Commercial Passenger Fishing Vessel (CPFV) fleet is unique in scale of operation, extensive fishing history, and economic impacts. The basses (Paralabrax sp.), which represent a principal target for the CPFV fleet, recently gained more stringent size limits and bag limits. The goal of this study was to conduct a survey of CPFV captains to assess perceptions regarding the status of two Paralabrax species, as well as the impacts of the new regulations. Catch and effort estimates were also obtained using CPFV logbook data to compare captains’ perceptions with actual changes in the fishery. The captains agreed that both species are vital to recreational fishing, and that the Barred Sand Bass stock is less healthy than Kelp Bass. Catch and effort analyses were consistent with this perception, with more dramatic declines in CPUE exhibited by Barred Sand Bass. The most experienced captains perceived the status of each species to be in a less healthy state than the less experienced captains, suggesting that shifting baselines are occurring. Most of the captains thought the increased minimum size limits had the greatest short-term impact on the fishing experience. The CPFV logbook data summaries support this assertion, but Kelp Bass CPUE showed a trend reversal. In contrast, Barred Sand Bass CPUE has precipitously declined, and spawning aggregations have been absent since 2013. The agreement between captains’ perceptions and logbook analyses strengthens the overall findings, and suggests captains are a valuable resource for informing fisheries management, especially in future studies with data-limited stocks. 相似文献
13.
Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts. 相似文献
14.
《African Journal of Marine Science》2013,35(3):315-322
South Africa's small pelagics fishery is moving towards a management strategy using an ecosystem approach to fisheries (EAF), with rights-based management (RBM) as the key rights allocation system. While EAF strives to balance between, among others, ecological and social-economic objectives, RBM is driving the sector towards economic efficiency. Within EAF itself, there are still underlying mismatches between the two top objectives, ‘human wellbeing’ and ‘ecological wellbeing’, in effect requiring a better balance between these objectives than there is currently. For example, fishers do not believe they should be competing with marine mammals and birds for allocation of the resource, yet this is one of the primary trade-offs that have to be made when setting the annual total allowable catches (TACs) under EAF. A balance between the two objectives could be achieved through acceptable trade-offs between them among all stakeholders within inclusive governance. Implementation of RBM has had both positive and negative effects on the objectives for EAF. Of concern are the negative effects of RBM on human wellbeing. For example, fishers feel that RBM has weakened their bargaining position, thereby reducing their benefits. In addition, RBM has resulted in job losses and insecurity of employment within the fisheries sector. The most affected have been the most vulnerable — the low level workers — who ought to be the key beneficiaries of RBM. Thus prioritising and protecting vulnerable groups and fishing communities need careful consideration when creating RBM, even in the context of EAF. Rights-based management has also had negative effects on ecological wellbeing through practices such as increased dumping and ‘high grading’ as part of industry's drive for increased efficiency under RBM. Whereas scientists believe that variability is largely due to environmental conditions, fishers strongly feel that dumping, high grading and high fishing pressure are the main factors. One of the positive aspects of RBM has been improved understanding among rights-holders and fishers of the need to consider other organisms in the TAC and to protect these through establishment of marine protected areas, island perimeter closures and limiting bycatch, thereby impacting positively on ecological wellbeing. 相似文献
15.
《Marine Policy》2015
Commercial fishing data were used to reconstruct historical spatio-temporal patterns of fishing effort and landings in the bottom longline fishery of the Azores. Key events during an important 15-year period were charted, through fisher interviews together with GIS analysis. While effort distribution varied over time, the prevailing pattern was a shift in focus from eastern to western areas and from shelf/slope to offshore banks and seamounts in response to policy measures (e.g. banning bottom longline inside 3 NM, public aids for modernization of the fleet) and reduced fishing yields. Areas 12–50 NM from shore represented the most vital fishing grounds in terms of fishing effort and production. Declining landings of the major demersal species, in recent years, indicate that present catch levels are not sustainable and further measures need to be taken in order to sustain fisheries resources. Knowledge of fleet behavior and the distribution of fishing effort, particularly in patchy environments, provide valuable insights into the impacts of past management decisions and help predict the outcome of new policies both in this region and elsewhere. 相似文献
16.
The Eastern Baltic cod stock was until recently below safe biological limits and suffered from high fishing pressure. In most recent years, fishing mortality substantially declined and spawner biomass more than tripled. Similar developments have not been observed for any other depleted cod stock in the North Atlantic during the last few decades. This paper investigates relative impacts of changes in different ecological and management-related drivers, which could have contributed to the rapid recovery of the Eastern Baltic cod. The results show that the success to reduce fishing mortality below management target in 2008 was due to a combination of increased recruitment and improved compliance with TAC. The reversal of the negative trend in biomass and rebuilding of the stock to the present level were largely driven by increased recruitment. Harvest control rules of the multi-annual management plan for setting TACs currently maintain the fishing mortality at a low level, which allows the stock to accumulate biomass and further accelerate its recovery. Relatively strong incoming year-classes and recently better control over removals distinguish the Eastern Baltic cod from other depleted European cod stocks, which have not shown similar positive trends in recent years. Sound management measures and compliance to those as well as favourable biological conditions are required for a successful stock recovery. 相似文献
17.
《Marine Policy》2013
Tropical small-scale fisheries are highly heterogeneous with respect to a wide range of fisheries characteristics, but that heterogeneity has generally not been adequately studied or considered in management. This study investigated fisheries heterogeneity and the extent to which it is accounted for in management regulations in eight small-scale fishing communities located in floodplain ecosystems of the Amazon basin. Analyses of 29,844 fishery landing interview data revealed that fisheries heterogeneity with respect to gear, habitat, species composition, and total catch and fishing effort was high across all communities, but low over the years in the same communities, indicating that each community must be considered as a distinct management unit. Data analyses also revealed that many important community fisheries characteristics were not accounted for by government- and community-based management regulations. Total catch and fishing effort were largely unregulated; there were no size or closed season limits for one-third of the most important fishery species; and the nursery habitats used by most fishery species were not protected in any fashion. Clearly, increased attention to cross-community fisheries heterogeneity can improve the design and implementation of management regulations. The management problems created by the heterogeneity of small-scale fisheries are discussed, and the potential of the “barefoot ecologist” concept to address them is considered. 相似文献
18.
Although failures and successes in fisheries management are related to decision making processes, these are rarely analyzed in detail and even less often following quantitative or semi-quantitative approaches. Herein, we study the decision making process for Chile's most important fisheries using a binary decision model. This model evaluates the probability that an annual total allowable catch (TAC) will or will not be modified by the National Fisheries Council (NFC) based on biological, economic, and social factors. We also analyze some aspects of individual voting, particularly whether the members vote against or abstain from voting on the proposed TAC and if they prioritize resource conservation objectives. Our results indicate that the risk of over exploitation for many important stocks in Chile is aggravated by failures at the decision making level: the scientifically recommended TACs for those fisheries that generate higher levels of employment and have greater economic value are normally increased. This analysis shows that the NFC has clearly prioritized short-term economic and social objectives over resource conservation goals. We discuss the need to adjust the composition and functioning of the NFC in order to ensure long-term sustainability of the fisheries. 相似文献
19.
《Marine Policy》2013
The performance of the EU long-term management plan for cod stocks, in force since 2009, is analysed focusing on the human and institutional factors. The plan operates through landings quotas (TACs) and effort restrictions following a Harvest Control Rule, and deploys a novel instrument allowing Member States to ‘buy back’ or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the ‘buy-back’ instrument has led to increased uptake of selective gear and implementation of permanent and real-time temporary closures. On the negative side, ignoring the dimension of fishers as reactive agents in the design, the impact assessment, and the annual implementation of the measures has contributed to the failure to adequately implement the plan and achieve its objectives. The main problem is that the landings quotas taken in a mixed fishery did not limit catches because fishers were incentivised to continue fishing and discard overquota catch while quota for other species was available. The effort limitations intended to reduce this effect were insufficient to adequately limit fishing mortality in targeted fisheries, although fishers experienced them as prohibiting the full uptake of other quotas. Recommendations for future plans include (i) management through catch rather than landings quotas, (ii) the internalisation of the costs of exceeding quotas, (iii) use of more selective gear types, (iv) the development of appropriate metrics as a basis for regulatory measures and for evaluations, (v) participatory governance, (vi) fishery-based management, (vii) flexibility in fishing strategy at vessel level. 相似文献
20.
《Marine Policy》2016
Recreational fishing mortality can have a major impact on coastal fish populations, bringing recreational fishers into conflict with commercial fisheries. This article reviews exclusion zones for commercial fishing, or ‘recreational fishing areas’ as a solution to the conflict between commercial and recreational fisheries. Recently designated recreational fishing areas in the state of Queensland, Australia are examined as a case-study. The goal of recreational fishing areas is to enhance recreational fishing and provide economic opportunities through charter fishing. However, recently designated recreational fishing areas in Queensland have not been thoroughly assessed for their social, economic and environmental impacts and they are not integrated within existing management frameworks for fisheries. The designation of recreational fishing areas is thus a shift away from evidence-based management in Queensland's fisheries and has likely occurred solely for political reasons – there are more voters in the recreational fishery than commercial fishery. In Queensland, excluding commercial fishing on its own is unlikely to result in long-term benefits to recreational fisheries because recreational harvest is a major component of fish harvest for some key species and there is no legislated limit to recreational harvest. Current political attention on recreational fishing areas provides an opportunity for fisheries managers, politicians, conservation groups and the public to discuss what is needed to manage sustainable coastal fisheries. In particular, recreational fishing areas need to be combined with efforts to enhance stewardship among recreational fishers if they are to be successful in the long-term. 相似文献