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1.
《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
2.
《Marine Policy》2016
An important component of science-based fisheries policy is the provision of habitat adequate for population renewal. In Canada, the Fisheries Act pays little attention to managing fish habitat, and was further weakened by changes enacted in 2012. Specifically, determining the role of fish habitat in contributing to fisheries and fish stock recovery is challenging when many stocks have severely declined and no longer occupy former habitats. This study compared the abundance of juvenile fish in coastal vegetated habitats before and after collapse or decline of groundfish stocks in Atlantic Canada. This comparison was done by compiling past studies that surveyed juvenile Atlantic cod (Gadus morhua) and pollock (Pollachius virens) in vegetated habitats across three provinces. Two studies were repeated, and one that already had post-collapse data was analyzed to quantify long-term changes in juvenile abundance. In all three cases substantial reduction in juvenile abundance coincided with declines in adult stocks. However, juvenile fish still occur in coastal habitats and could aid in adult stock recovery. The current version of the Canadian Fisheries Act requires presence of an ongoing fishery to trigger habitat protection. This is problematic as low fish abundance may lead to lowered habitat protection and potentially habitat degradation, with less or lesser-quality habitat for fish in the future. Thus, recommendations are made to repeal the 2012 Fisheries Act changes and enhance current fish habitat legislation. Using a precautionary approach for coastal fish habitat management, particularly in valuing its potential for fish stock recovery, would strengthen Canadian fisheries management. 相似文献
3.
Many fish stocks in the world are depleted as a result of overexploitation, which reduces stock productivity and results in loss of potential yields. In this study we analyzed the catch trends and approximate thresholds of sustainable fishing for fished stocks to estimate the potential loss of catch and revenue of global fisheries as a result of overexploitation during the period of 1950–2010 in 14 FAO fishing areas. About 35% of stocks in the global marine ocean have or had suffered from overexploitation at present. The global catch losses amounted to 332.8 million tonnes over 1950–2010, resulting in a direct economic loss of US$298.9 billion(constant 2005 US$).Unsustainable fishing caused substantial potential losses worldwide, especially in the northern hemisphere.Estimated potential losses due to overfishing for different groups of resources showed that the low-value but abundant small-medium pelagics made the largest contribution to the global catch loss, with a weight of 265.0 million tonnes. The geographic expansion of overfishing not only showed serial depletion of world's fishery resources, but also reflected how recent trends towards sustainability can stabilize or reverse catch losses.Reduction of global fishing capacity and changes in fishery management systems are necessary if the long-term sustainability of marine fisheries in the world is to be achieved. 相似文献
4.
《Ocean & Coastal Management》2006,49(7-8):385-412
The Guinea Current Large Marine Ecosystem (GCLME) extending from Bissagos Island (Guinea Bissau) in the north to Cabinda (Angola) in the south defines the shared transboundary waters off the coast of western Africa, which embodies some of the major coastal upwelling sub-ecosystems of the world and is an important centre of marine biodiversity and marine food production. The GCLME is characterized by distinctive bathymetry, hydrography, chemistry, and trophodynamics and represents the number 28 Large Marine Ecosystem (LME) ranked among the most productive coastal and offshore waters in the world with rich fishery resources. However, over-exploitation of fisheries, pollution from domestic and industry sources, habitat destruction and poorly planned and managed coastal developments and near-shore activities are resulting in a rapid depletion of the rich fisheries resources and degradation of vulnerable coastal and offshore habitats putting the economies, productivity and health of the populace at risk. Recognizing the urgency of the fisheries decline and the environmental and socio-economic consequences for the region, the 16 countries bordering the ecosystem have mobilized complementary resources to the funding from the Global Environment Facility and United Nations Industrial Development Organization to implement priority management actions agreed in the preliminary Strategic Action Programme for the recovery of depleted fish stocks and restoration of degraded habitats for the advancement of the achievement of the World Summit on Sustainable Development (WSSD) Johannesburg Plan of Implementation targets for recovery of fish stocks. 相似文献
5.
Fishermen, scientists, national policy makers, and staff of environmental NGOs (ENGOs) hold different perceptions about temporal patterns in fish stocks. Perception differences are problematic in multi-stakeholder settings, because they elicit controversies and unbalanced disputes. These hinder effective participation, a prerequisite for ‘good governance’ and effective management of sustainable fisheries. This study shows that perceptions of change (‘does the stock increase or decrease?’) and of current status of a fish stock (‘is it doing well or not?’) are influenced by the capturing and processing of information, rather than by interests alone. We focused on the Dutch North Sea fishery on plaice and sole and examined (1) availability and accessibility of information on temporal patterns of these stocks and (2) perception differences between all parties. A first explanation for these differences is the use of different parameters as a measure for stock size. Fishermen focus on catch rates or catch-per-unit-effort (relative stock size), whereas scientists, policy makers, and ENGO-staff mainly use scientific assessments of spawning stock biomass (absolute stock size). Between-group perception differences are further explained by spatial aggregation levels of information, lengths of time series evaluated, and by modes of comparison to qualify the current status of fish stocks. Awareness of information differences and the development of shared information use and processing may release some of the tensions in multi-stakeholder settings debating fisheries management. However, comprehension problems amongst all parties on how spawning stock biomass is reconstructed and how it relates to catch rates in the fishery may pose an enduring barrier. 相似文献
6.
Sustainable management of wild fish stocks by means of catch quotas requires reliable data on fishing mortality. Norwegian authorities have attempted to ensure the reliability of this data through catch report procedures and a ban on dumping. The reliability of data on fishing mortality depends on the fishers’ compliance with these regulations. This article outlines the main factors that govern compliance and non-compliance in the Norwegian pelagic fisheries. Data was generated during fieldwork in the offshore pelagic fishing fleet. 相似文献
7.
《Marine Policy》2017
Spatially sensitive management built on detailed biological and socio-economic knowledge is required to establish sound fishing regulations and to avoid extinction of small coastal populations of fish and shellfish. Highly productive isolated populations of several commercial species have historically inhabited the Swedish west coast, but during the past century these populations have been depleted by fisheries and with no sign of recovery. Since 1999 several fisheries regulations and different stakeholder co-management initiatives have flourished along the Swedish coast of the Skagerrak. They aimed to facilitate the recovery of collapsed local stocks but the established regulations failed to identify and restrict the main sources of mortality acting on local stocks and they have thus been ineffective to promote the recovery. Furthermore, regulations have operated on the weakest among stakeholders (e.g.. recreational fishers), which have minor influence over management, and the restrictions have been imposed without providing any data which supported the choice (i.e. the “easy restriction” syndrome). In line with the general “spirit” of recent Swedish fishery management, we conclude that managers, without the disapproval of Swedish scientists, have circumvented limitations which should address the largest mortality factor, i.e. the commercial fishery. The regulations presently in place, have been politically uncontroversial and easy to implement, but have been highly unsuccessful. We therefore suggest that stakeholders, including politicians, should start focusing on more effective and science-based management and less on what is politically attractive if Swedish citizens shall have a chance to witness the recovery of their once flourishing coastal populations. 相似文献
8.
《Marine Policy》2014
As catch and effort statistics including fishing time and location are essential for producing abundance indices for utilized fish stocks, fishing states are encouraged under the FAO Code of Conduct for Responsible Fisheries to collect and maintain such statistics. However, for coastal fisheries (including artisanal fisheries) that are mainly composed of small-sized vessels which are usually too numerous to monitor, fisheries statistics collection systems are often either lacking or of insufficient quality (e.g. incomplete or inaccurate). Vessel monitoring system (VMS) data are commonly used to construct or improve estimation of fishing effort and fishing location in large-scale fisheries. Most coastal fisheries lack VMS but their countries do have coastal surveillance radar systems (CSRS) for security and enforcement purposes. This study illustrates and recommends opportunistic use of CSRS data to provide similar scientific benefits to VMS data for coastal fisheries. CSRS in combination with market landings data can construct logbook-like catch and effort statistics. This study introduces a method and demonstrates its usefulness for scientific research and management purposes, including the potential to obtain a higher accuracy and precision, particularly for fishing location and catch amount. Limitations of the CSRS data and challenges to managers involved in its application are also discussed. 相似文献
9.
《Ocean & Coastal Management》1999,42(6-7):569-590
Increasing populations and development in many of the small Pacific Island nations have placed heavy pressures on coastal environments and on inshore fisheries. The population of Samoa, in the Southwestern Pacific, has increased 5–6-fold in the past 150 years. Wetlands, lagoons and coral reefs have been seriously degraded because of inappropriate land-use and fisheries practices and recent catastrophic cyclones, and many fish and invertebrate stocks have declined in the past 10–15 years. A research program was established in 1990 to determine the status of the coastal and inshore environments, to monitor inshore subsistence and commercial fisheries, to determine the status of stocks, and to identify potential management actions. An inventory of inshore resources was produced using aerial photography and ground and underwater surveys. Fisheries catch and effort were established through a national census, questionnaire surveys in households and schools, and creel and market surveys. A major aid program was commenced in 1995 by the Australian government (AusAID) to assist Samoa to establish an effective inshore fisheries and environment management program. A key strategy was the devolution of powers in inshore fisheries management back from the national government to the villages and local fishers. A culturally appropriate co-management model was developed and tested, and has now been adopted by many villages. An inshore fisheries extension capability was developed within Samoa's Fisheries Division to assist villagers to undertake their own environmental and fisheries surveys; identify major factors affecting fisheries; identify ways of reducing these factors; establish an agreed (between village council and national government) plan of management and regulations; and establish their own fisheries management bodies. By the end of 1997 the Inshore Fisheries Extension Service had been established and trained; 26 villages had entered the co-management program and established their own plans of management; and 20 fisheries reserves had been established. The techniques for inshore environmental and fisheries assessment and management developed for Samoa are applicable, with appropriate modification, to subsistence fishing communities elsewhere in the South Pacific. 相似文献
10.
Dietmar Grimm Ivan Barkhorn David Festa Kate Bonzon Judd Boomhower Valerie Hovland Jason Blau 《Marine Policy》2012,36(3):644-657
What are the effects of transitioning traditionally managed fisheries to incentive-based catch shares fisheries? In a study of all major United States federal catch share fisheries and associated shared stock fisheries in British Columbia, catch shares result in environmental improvements, economic improvements, and a mixture of changes in social performance, relative to the race for fish under traditional management. Environmentally, compliance with total allowable catch increases and discards decrease. Economically, vessel yields rise, total revenues grow, and long-term stock increases are encouraged. Socially, safety increases, some port areas modestly consolidate, needed processing capacity often reduces, and labor markets shift from part time jobs to full time jobs with similar total employment. Newer catch shares address many social concerns through careful design. 相似文献
11.
Kui Zhang Ping Geng Jiajun Li Youwei Xu Muhsan Ali Kalhoro Mingshuai Sun Dengfu Shi Zuozhi Chen 《海洋学报(英文版)》2022,41(3):24-33
Long-term variations in population structure, growth, mortality, length at median sexual maturity, and exploitation rate of threadfin bream (Nemipterus virgatus) are reported based on bottom trawl survey data collected during 1960–2012 in the Beibu Gulf, South China Sea. Laboratory-based analyses were conducted on 16791 individuals collected quarterly in eight different sampling years. Average body length, estimated asymptotic length, and percentage of large individuals have decreased significantly with the growth of marine catch and fishing power, indicating individual miniaturization of this fish species. Estimated exploitation rates indicate that the N. virgatus stock in the Beibu Gulf was moderately exploited in 1960 and 1962 and overexploited after 1992. This stock was taking a good turn in status in 2012, with the lowest exploitation rate since 1992 and ceased downward trend in length indexes. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of this commercial fish species. Biological characteristics of most commercial fish species have phenotypic plasticity and might change over years in response to fisheries management. Therefore, attentions should be paid on variations in fish biological characteristics, when evaluating the effectiveness of current measures to control the total catch for all fisheries. 相似文献
12.
《African Journal of Marine Science》2013,35(1):307-315
The hake resource is the most important commercial fish species in the demersal sector of Namibia's fisheries, both in terms of annual catch and contribution to Gross Domestic Product (GDP). The fishery now spans four decades. In the 1960s and 1970s, hake were exploited heavily by mainly foreign fleets, total catches peaking at more than 800 000 tons in 1972. The first control measures, the use of a minimum mesh size of 110 mm and the allocation of quotas to each member country participating in the hake fishery, were implemented by the International Commission for the Southeast Atlantic Fisheries in 1975. In 1990, the Namibian Government took action to control fishing activities in Namibian waters, and the enactment of its Fisheries Policy (1991) and Sea Fisheries Act of 1992 provided for the control measures to be taken. The conservative management strategy adopted between 1990 and 1993 resulted in gradual increase in hake biomass, but thereafter the stock declined. The hake fishery is currently managed on the basis of a total allowable catch that takes into consideration the rate of increase or decrease in the size of the resource. Since 1990, the demersal trawl fishery has accounted for approximately 90% of the total hake catch. The resource is subjected to both directed fishing and bycatch, the latter taken in directed fisheries for species such as horse mackerel, monkfish and sole. 相似文献
13.
《African Journal of Marine Science》2013,35(3):277-287
Standardised sampling protocols for monitoring fish stocks are essential to assess changes in stock status and provide a means to evaluate the effectiveness of fisheries management measures, such as marine protected areas (MPAs). This study aimed to optimise two standard sampling methods, namely underwater visual census (UVC) and controlled angling, for assessing subtidal reef fish communities. In terms of efficiency, variability and bias, UVC transects were found to be superior to point counts. For controlled angling, an effort of two angler-hours per fishing station provided low catch variability, high catch per unit effort and a representative catch. Whereas UVC provided less variable estimates of relative density, controlled angling provided greater sampling efficiency. It is thus recommended that the two methods be used in conjunction. The optimal sampling protocols identified are suitable for rapid assessments or long-term monitoring of subtidal, temperate reef fish communities. 相似文献
14.
《Marine Policy》2013
Most worldwide fish stocks are overexploited, and so exploited beyond the Maximum Sustainable Yield (MSY) and the Maximum Economic Yield (MEY). Not exploiting fisheries resources at MSY or MEY leads to the loss of production and rents from the fisheries. A large part of the EU fisheries are managed based on single species stock assessments; however, in reality, most species are caught together with other species and by different fleets. In multi-species and multi-fleet fisheries, single species assessments, and consequently MSY and MEY reference points, are often not valid, and so the catch recommendations. In this paper it is investigated the MSY and MEY estimation in multi-species and multi-fleet fisheries in comparison to single species assessments. Analyses are applied to the Bay of Biscay demersal fishery using the IAM bio-economic model. The impact of exploiting at MSY and MEY on the optimal effort allocation between fleets with different exploitation patterns and economic structures is analyzed. When accounting for the multi-species nature of the fishery, MSY landings are 0.4% to 2.7% lower than the single species simulations estimates. When accounting for the multi-fleet nature of the fishery, MSY landings are 27.2% to 30.2% higher than the single-fleet estimates. When considering the multi-fleet characteristics, MEY landings are 6.6% higher and profits are 66.5% higher than in the single-fleet simulation. Optimal effort at MEY is lower than at MSY, but when accounting for multi-fleet the optimal effort decreases for some fleets while increases for gillnetters. The results also provide an estimation of the profits at MEY (or costs of not being at MEY). Profits can be then up to 10.7 times larger than the current profits (256 million Euros compared to the current 24 million Euros). 相似文献
15.
《African Journal of Marine Science》2013,35(3):613-624
This study describes the Thukela Banks crustacean and linefish fisheries and investigates the potential impacts of reduced flow from the Thukela River on the value of these fisheries. Data were obtained from published and unpublished material, key informants and government records. The crustacean fishery employs about 300 people, and comprises an inshore and offshore fishery. Inshore catches and effort are strongly seasonal, peaking in April to June. The probability of fishing in any particular month is positively correlated with catch per unit effort. Average overall annual catch (inshore and offshore) was estimated to be in the region of 700 tonnes for 1992–2002 with a gross output of about R36.7 million per annum, and a gross value added (net output) of R13.8 million (1 US$ = R6.40; 2003). Inshore prawns were estimated to contribute R8.5 million of the gross output. The Thukela Banks was estimated to contribute R4.5 million and R35 million (rand value in 2003) to the gross output of the commercial linefishery and boat-based recreational angling fishery respectively. Freshwater reduction scenarios yielded 0.7–11% reductions in prawn catches, which translated into only a 1–2% drop in the annual value of the fishery. The latter was attributed to the fishery's diversity (predominantly the buffering effect of bycatch) and the fact that the stocks of the species targeted by the offshore component are largely independent of flow. Catches and value of the recreational boat-based linefishery were predicted to remain fairly constant irrespective of any changes in flow. The commercial linefishery was the most responsive, with a 20% decline in total catch and 17% value predicted for the most extreme flow reduction scenario. 相似文献
16.
《Marine Policy》2001,25(1):43-48
A new approach to fisheries management is suggested. Recognizing the great uncertainty and variability that affects the supply of fish, combined with the immobility of capital and labor in the industry, a small core fishery should be maintained with the capacity to catch only the quantity of fish that it would be safe to catch as the stock approaches the lower limits of its natural cycle. When fish are abundant, the excess would be auctioned to risk takers who have neither a permanent commitment to, nor multi-year fishing rights in, the fishery. 相似文献
17.
《African Journal of Marine Science》2013,35(1):81-110
The Cape commercial linefishery, established during the first half of the 19th century, currently consists of about 2 500 vessels (±20 000 crew), which land some 15 500 tons of fish each year. In spite of a long history, a lack of a long-term catch and effort data series has severely hindered the management of the fishery. This paper providcs commercial catch and effort data for three periods during the 20th century: 1897–1906, 1927–1931 and 1986–1998. Trends in catch per unit effort (cpue) were verified with additional data from the inshore trawl-fishery, from fishery-independent surveys and, where possible, stock assessment. According to a Linefish Management Protocol developed for the Linefishery, any stock demonstrating a historical reduction in cpue or catch contribution of more than 75% is to be regarded as overexploited. Evaluations based on present datasets support this arbitrarily determined reference point for cpue, but reveal that catch composition is a poor indicator of stock status and should be used with caution. In spite of technological advances such as the advent of combustion engines, nylon lines. echo-sounders, electronic navigational aids, onboard freezer facilities and larger vessels, declines in catch rate indicative of severe overexploitation (i.e. 75–99%) were observed for many important linefish species during the 20th century. Most of these were higher-trophic-Level species from the warm/temperate East Coast, several of which are also endemic. Life-history characteristics of the vulnerable species (i.e those demonstrating declines in cpue of >75%) include predictable location in time and space (either coastal migrant or resident), longevity (>15 years) and late maturity (relative to maximum age). Apart frorreduced productivity associated with stock depletion, other setbacks, such as ecosystem alteration, loss of genetic diversity and shor-term commercial extinction, are also anticipated. In order to rebuild depleted linefish stocks it is deemed essential to create additional marine reserves, dramatically improve enforcement, develop extensive public awareness programmes and substantially reduce commercial effort. 相似文献
18.
胶州湾大型无脊椎动物数量的多年变化与趋势预测 总被引：7，自引：4，他引：7
利用1981，1985，1989，1993年5月和8月的定点拖网资料，选出大型无脊椎动物主要种，研究其多年变化规律，并预测其变化趋势，统计结果表明，各年5月份的平均捕获量分别为：1981年1252，1985年，1480，1989年1076，1993年556个／（网．时），呈明显的指数下降趋势，这种趋势符合X＝－4275.244e^-0.4302066t 5527.244的规律，每年8月份的资料量分别为：1981年3190，1985年8474和2027，1993年631个／（网．时），呈明显的指下降趋势，这种趋势符合X＝－4275.244e^-0.4302066t 5527.244的规律，每年8月份的资源量分别为，1981年3190，1985年8474，1989年2027，1993年631个／（网．时），亦明显的下降，符合X＝－1126．9e^-1.202198t 14456.9的规律，以上变化趋势表明，若不采取有关措施，资源将近枯竭。 相似文献
19.
Designing and implementing long-term management plans is difficult both because of the complexity of the fisheries system, and the behaviour of humans. We compared four alternative management plans for the Baltic salmon stocks through approaching experts who interpreted and expressed the views of different stakeholder groups on the options. The focus of the study was on stakeholders’ commitment to the alternative management plans. Committing enhances the probability of achieving the ultimate objective of a plan, while if stakeholders do not commit, the effects of the plan may be less predictable. Thus commitment is an important part of implementation uncertainty in fisheries management. We present how we coupled qualitative analysis with probabilistic Bayesian networks in analysing expert knowledge related to alternative long term management plans in terms of group commitment. Using a Bayesian net provides potential for creating a holistic picture of a fishery by combining the data describing fishers’ commitment with biological data regarding fish stock dynamics and with economic data analyzing economically sound fisheries management. 相似文献
20.
《Marine Policy》2013
This study establishes an offshore and coastal fisheries policy indicator system to evaluate the performance of policies to achieve sustainable development in offshore and coastal fisheries. A modified Delphi method is used to establish this system, and the weights of indicators are calculated using the analytic hierarchy process (AHP) to aggregate indicators. Results show that ecological policies have not achieved their goals because production and catch per unit effort are decreasing. Indicators with respect to management efficiency have increased after the implementation of the buyback and off-fishing programs. However, net returns indicator, which is affected by increasing cost and production value, is stable. Due to inefficient management resulting from insufficient resources, indicators for the number of illegal fishing cases per year and the number of smuggled aquatic production incidents have increased. This shows that requirement for enhanced compliance is necessary. The objective for cultivating talents in fisheries has not been achieved because average wage for fishers is lower than the average civil wage, resulting in an increase in the hiring of foreign fishers. 相似文献