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1.
The European Union has established a framework to achieve or maintain good environmental status in the marine environment by 2020. The Marine Strategy Framework Directive requires the application of the ecosystem approach to the management of human activities, covering all sectors having an impact on the marine environment. However, fisheries in the Mediterranean are far from a systematic implementation of an ecosystem-based fisheries management (EBFM). Aiming to address this issue, this study explores the potential of the relationship between daily yield by vessel (landings and income by species) and vessel position (known via vessel monitoring system) as a tool for fleet management. This approach is possible due to the current dynamics of Mediterranean fleets, with vessels returning daily to the harbour where landings are registered as weight and income by vessel. Moreover, vessels of >15 m total length have been compulsory monitored by VMS since 2005. A bottom trawl fleet that operates in the northwestern Mediterranean was chosen to develop this approach. Different groups of trawlers were identified, which could be linked to the strategies displayed by the fishermen that were mainly driven by the target species dynamics. Accurate knowledge of the fishing targets driving the fleet dynamics and of the fishing strategies at the vessel level (i.e. fishing ground habitat where the fishing pressure is exerted and corresponding landings) are shown to be a feasible tool for fleet management.  相似文献   

2.
This paper analyses the perceptions of Spanish fishermen working in Atlantic fishing grounds on current fishery regulation measures and the possibility of introducing transferable rights as is established in the EC's latest proposal to reform the Common Fisheries Policy. A survey was conducted through face-to-face interviews and ordered logistic and multiple regression models to identify which characteristics influence fishermen's perceptions and attitudes. The results show that the fleet segments most in favour of implementing ITQs correspond to industrial fishing, while the smaller-scale fisheries (artisanal, gillnets, longline and coastal trawl) are more in favour of a system involving individual effort (fishing days or kW days), transferable or otherwise.  相似文献   

3.
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   

4.
Fisheries statistics provided by the Hellenic Statistical Authority (HELSTAT) have been often criticized for unusual estimates in landings and fishing effort data and for limitations in the sampling methodology, although there is no study on the identification of these biased and misreporting estimates. In the present study the landings per species and fishing subarea, as well as the fishing effort data per fishing gear reported by HELSTAT were analysed over the period 1982–2010. The results showed abrupt changes of both the recorded species and species landings per subarea, spurious correlations of landings among different species groups and misreporting estimates in the number of fishing vessels per fishing gear. These might be likely attributed to: (a) differences of the HELSTAT administrative infrastructures at local scale, (b) changes in the sampling protocol followed by HELSTAT, (c) reporting faults made by HELSTAT, (d) fisheries restrictive measures at local basis, (e) other factors that increased the bias and the uncertainties of HELSTAT fisheries data and related to socio-economic (i.e. fuel price) and operational (i.e. spatial structure of the fisheries fleet) aspects and/or (f) to environmental changes that might possibly affected fisheries dynamics. The present study aims to the improvement of the effectiveness of the national fisheries statistics as pinpointed by Common Fisheries Policy in order to avoid imprecise and/or biased estimations about the state of the fisheries.  相似文献   

5.
Both foreign and domestic pelagic longline fishing vessels operate in South Africa’s Exclusive Economic Zone and adjacent international waters where they kill hundreds of seabirds each year as bycatch. To update assessments of the impact of the pelagic longline fishery on seabirds off South Africa, information on necropsied seabirds and national fisheries observer bycatch records were summarised for 2006–2013. Foreign-flagged (Asian) vessels had 100% observer coverage throughout the study period, whereas only 6% of the fishing effort by South African-flagged vessels was observed (with no coverage in 2011–2013). Vessels with observers caught seabirds at a rate of 0.132 birds per 1 000 hooks, resulting in an estimated mortality of 2 851 individuals (356 per year) comprising 14 species. Extrapolation of the observed fishing sets to the unobserved fishing sets by the South African domestic longline fleet suggested that approximately 750 additional birds were likely killed during the study period, therefore a combined 450 birds were killed per year. White-chinned petrel Procellaria aequinoctialis was the most frequently killed species (66%), followed by ‘shy-type’ albatrosses Thalassarche cauta/steadi (21%), black-browed albatross T. melanophris (7%), Indian yellow-nosed albatross T. carteri (3%), and Cape gannet Morus capensis (2%). The seabird bycatch rates were lower than in 1998–2005. Nationality of the vessel, time of line-setting, moon phase, year, season, fishing area, and seabird bycatch mitigation measures all influenced seabird mortality. Concurrent with 100% observer coverage, significant reductions in the seabird bycatch rate occurred in the Asian fleet in the latter years of the study, and these rates now approximate the national target (0.05 birds per 1 000 hooks). However, seabird bycatch rates remained high in the South African fleet, where no observers were deployed during 2011–2013, highlighting the need for independent observer programmes in fisheries—a matter of global interest. Suggestions are made as to how seabird bycatch by pelagic longline fisheries off South Africa may be further reduced.  相似文献   

6.
Whale depredation occurs when whales steal fish, damage fish or damage fishing gear. In Alaska, killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) primarily depredate on demersal sablefish (Anoplopoma fimbria) and Pacific halibut (Hippoglossus stenolepis) longline fisheries. Quantitative data on whale depredation in Alaska is limited due to low fishery observer coverage and minimal depredation evidence left on longline fishing gear. This study utilized semidirected interviews (n=70) and written questionnaires (n=95) with longline fishermen to examine: (1) perceptions and experiences of whale–fishery interactions in Alaska, (2) effects of depredation on fishing practices, and (3) potential depredation mitigation measures. Eighty-seven percent of fishermen surveyed agreed that whale depredation became worse between 1990 and 2010. Respondents reported changing their fishing practices in response to depredating whales in several ways, including: traveling up to 50 nautical miles and ceasing hauling operations up to 24 h until the whales left the fishing grounds. Respondents fishing in western Alaska, primarily encountering killer whales, were forced to wait longer and travel greater distances than fishermen operating in central and southeast Alaska, regions more affected by sperm whales. Deterrent research, gear modifications and real-time tracking of depredating whales were solutions favored by study participants. Survey respondent answers varied based on areas fished, quota owned, years involved in the fishery and vessel size. This study presents the first statewide evaluation of fishermen's perception and knowledge of whale interactions with the Alaskan longline fleet and is a critical step toward developing baseline data and feasible depredation mitigation strategies.  相似文献   

7.
The present study assessed trends in resource-use, partitioning and management in the Ungwana Bay fishery, Kenya, using surplus production models. The fishery is one of East Africa’s important marine fisheries sustaining a bottom trawl commercial fishery and a resident-migrant artisanal fishery. Two models: Schaefer (1954) and Gulland and Fox (1975) were applied to catch-effort data over a 21-year period to model maximum sustainable yield (MSY) and optimal effort (fMSY) to examine the status of resource exploitation and provide reference points for sustainable management. In the artisanal fishery, model MSYs range from 392-446 t to 1283-1473 t for shrimps and fish respectively compared to mean annual landings of 60 t for shrimp and 758 t for fish. These landings represent <50% of the model MSYs suggesting under exploitation in the sub-sector. Moreover, current fishing effort applied stands at <0.5 fMSY. On the other hand, mean annual landings in bottom trawl commercial fishery, at about 330 t for shrimps and 583 t and fish represent about 90% of the model MSYs of 352-391 t and 499-602 t for shrimps and fish respectively. Therefore, the bottom trawl commercial fishery is likely under full exploitation. Similarly, the current effort is estimated at >0.7 fMSY. Resource management in the bay is faced with numerous problems including resource-use conflicts, poor economic conditions in artisanal fishery, poor legislation, and inadequate research augmented by poor reporting systems for catch-effort statistics. Thus, the fishery lacks clearly defined exploitation regimes. Fisheries research and assessment of the marine resources are important for sustainability of the fishery. Moreover, income diversification in the poverty ridden artisanal fishery would go a long way in addressing resource-use conflicts and use of deleterious fishing methods in the sub-sector. Borrowing from the successes of the Japanese community-based fisheries resource management (CBFRM) which has easily resolved numerous fisheries management issues in coastal small-scale commercial fisheries, and the beach management unit (BMU) system which has been applied to the artisanal fisheries of south coast Kenya with enormous benefits, it is envisaged that a hybrid CBFRM-BMU system presents the best approach to sustainable resource-use in the Ungwana Bay fishery.  相似文献   

8.
Much of the research that concerns the impacts of management measures in the eastern Baltic cod fishery has focused on fish stock rather than understanding fishermen's attitudes towards regulations. Hence, there is little information available on fishermen's responses although they are the ones whom the regulations affect most profoundly. This study analyses the views of fishermen towards management measures with an emphasis on fishing closures (marine protected areas, MPAs). Swedish log-book data from 1996 to 2005 were used to describe MPA induced fishing effort displacements. Fishermen argued that MPAs have been inefficient in conservation of cod stock. The enlargement of Bornholm MPA in 2005 caused substantial effort displacement towards areas dominated by smaller sized fish. This contributed to the increased discarding of juvenile cod. Enlarged MPAs also intensified competition between different fleet segments and reallocated fishing areas. To reduce fishing mortality, fishermen suggested days-at-sea (effort) regulation and an effective landings control system for all fleets that exploit cod stocks in the Baltic Sea Main Basin. These measures would better motivate fishermen for mutual rule compliance, which is a prerequisite for a sustainable cod fishery.  相似文献   

9.
Octopus vulgaris is the most important target species in Portuguese fisheries in terms of economic value, when all official and non-declared landings are considered. Around 10% of the landings in national waters come from the trawl fleet, which is both the least selective and the best documented métier in the fishery, allowing the simultaneous assessment of distribution and population structure. This study represents a first attempt to integrate different sources of information obtained at commercial trip-level, with the objective of providing a perspective of octopus population structure and relative distribution, together with information on the exploitation pattern in 2003. High-quality resolution of sequential geo-referenced data were obtained from the Portuguese Vessel Monitoring System for the fishing trips targeting octopus. Intensive fishing activity was observed inshore of two regions, one to the north of Peniche (from Cape Carvoeiro to Portuguese border) and the other between Cape St. Vicente (Sagres) and Cape St. Maria (Faro) in the South coast. Fishing trips undertaken between 39.5 and 42°N were used to provide information on volume and size distribution of landings. These show that smaller individuals (=<12 cm ML) are mainly concentrated between 40.5 and 41.5°N, whereas larger individuals (>12 cm ML) concentrate south of 41.5 and north of 40.5°N.  相似文献   

10.
A Dutch pilot study of fully documented fisheries provided the opportunity to observe actual changes in fishing behaviour under catch quota management (CQM). Interviews with fishers in the pilot study aided in interpreting the results and giving insight in the decision making process and reasoning of fishers. The CQM pilot study entailed a fleet of small and large demersal vessels. For these vessels, all cod catches were counted against quota, including catches of individuals below minimum landings size. To obtain reliable catch data all vessels were equipped with electronic monitoring (EM) systems. These systems recorded videos of all fishing and processing activities on board. In return, fishers received a 30% quota bonus for cod and were compensated with more flexibility on effort regulations. It was hypothesized that vessels in the CQM will (i) increase their landings by 30% according to their quota bonus, (ii) increase the use of gear with large mesh size, and (iii) change effort towards fishing locations with high catch rates of large cod and avoid areas with high catch rates of undersized cod. The results showed that CQM had no effect on fishing behaviour of the small vessels. In contrast, large vessels significantly increased their cod landings (216%) and avoided undersized cod. This difference in response of different fleets suggested that implementation of CQM, for instance in the context of the European Common Fisheries Policy, should consider fleet characteristics. It seemed that larger vessels in this study more easily adapted their behaviour to new management regimes and that the quota bonus opened up new fishing strategies, that were not envisaged during the implementation.  相似文献   

11.
After 16 years under a limited access program with effort controls, the New England groundfish fishery transitioned to a catch share management system in 2010. For much of its earlier management history, issues related to fishing capacity were paramount as effort controls were increasingly restrictive to meet biological objectives. As the size of the active fleet declined from over 1000 vessels from 1994 to 2001 to less than 400 vessels in 2012, the management concern shifted to fleet diversity. Fleet diversity has been cast in terms of vessels based on characteristics such as size, gear, and region rather than their share in landings or economic value. Measuring fleet diversity with indices commonly used in the biodiversity literature such as richness, effective diversity based on the Shannon index, and evenness appears appropriate for this context. In this paper these indices were applied to measure changes in diversity of the active New England groundfish fleet from 1996 to 2012. Fleet diversity as measured by the Shannon Index has declined by approximately 35% from 1996 to 2012, but has remained relatively stable since 2007. Forty vessel types were present in all 17 years, which accounted for about 85% of active groundfish vessels and over 90% of total groundfish landings in all years. Even though the fleet size and overall diversity have declined the “core” groundfish fleet remains stable.  相似文献   

12.
Cynoscion guatucupa Cuvier 1829 is a migratory pelagic fish species, which has a wide geographical distribution. It is the most important fishing resource for local communities in Bahía Blanca estuary and has been captured by artisanal fishermen since the 1900s. The industrial fleet has been fishing this species in the coastal area of Buenos Aires province since the 1950s, and, since 1970, landings have increased sharply. Between 2000 and 2004, the artisanal fishery in the estuarine waters of Bahía Blanca collapsed. Variations in total landings of the artisanal fleet might have arisen from the environmental variables within the estuary, fishing activity in the surrounding sea region, local pressure within the estuary and/or several other variables. Our results suggest that neither oceanographic parameters nor local pressure seem to have influenced the artisanal fishery of C. guatucupa in the estuarine region. Instead, this fishery seems to have been partially influenced by the increasing fishing pressure exerted by the industrial fishing fleet operating in open waters around the estuary. This study emphasizes the need to take into account fisheries data from both the estuarine environment and the surrounding sea region, particularly when designing management plans for the sustainable use of migrating fish resources.  相似文献   

13.
《Ocean & Coastal Management》2000,43(8-9):615-655
Almost 50 yr of global multispecies harvests are represented in the FAO capture production database, and offer a broad perspective on events that underlie the major observed changes in global marine harvests. The likely relevance of top–down and bottom–up trophic interactions, versus the impacts of changes in fishing technology and markets on the trophic level of landings, are discussed on a regional basis. Despite the low resolution of this global data set, several common features emerge. Rapid increases in fleet size and technological advance, and imperfect fisheries management measures, are probably responsible for declines in peak multispecies production in many areas since the 1970s, and internal evidence suggests that peak production is not far away in the remainder. Staggered dates of peak landings in different world areas seem to reflect the spread of industrial fishing fleets from `core areas’ to the rest of the world's oceans, which largely took place from the 1960s to 1990s. A general move to higher exploitation of piscivores in global landings is implied in some areas. The hypothesis that top–down removal of predators is affecting lower trophic production is however only one explanation for declining mean trophic levels, and is more likely to emerge from local food web studies. In some regions an increased proportion of short-lived invertebrates in harvests later in the time series supports a move downwards in trophic level targeting. In the North Atlantic and some other areas, fishing down marine food webs may be a likely cause of the increase in landings of shelf planktivores. A shift from depleted apical resources to species lower in the food web may have been made on economic grounds however, independent of possible effects of a release of predatory pressure. Sharp increases in planktivores later in the time series show up in the Eastern Central Atlantic and in the Southeast Pacific and do not appear to be primarily related to depletion of predators. They seem to reflect intermittent strength of upwelling systems, and hence bottom–up effects on food web production, together with changes in harvest technology. For some areas, piscivore landings increased later in the time series than those of planktivores. In the Mediterranean, this seems mainly a bottom–up response to increased marine productivity associated with land run-off and consequent improvements in predatory foraging. In some tropical areas, later increases in piscivorous landings mainly result from expansion of distant water tuna fleets, and are probably unrelated to exploitation of forage fishes. The technological revolution of the 1950s and 1960s involved rapid application of synthetic fibres to improved gear. This led to large-scale mid-water trawling and purse seining by industrial fleets and has especially increased vulnerability of small pelagic stocks over the last few decades. This appears mainly responsible for the apparent decline in mean trophic level of harvests in areas with large stocks of these resources. From an analysis of variances of the sample data set, `Punctuated equilibrium', involving actual changes in ecosystems, rather than just continuous change in the relative harvest rates of species in a given ecosystem, is suggested as an important phenomenon, reflecting both ecological change and changing exploitation strategies.  相似文献   

14.
In Florida, United States, the Caribbean spiny lobster, Panulirus argus, supports an important commercial fishery and also perhaps the most intensive recreational fishery of any lobster species, with sales of recreational lobster fishing permits exceeding 100 000 annually. For the past decade, we have used mail surveys of recreational lobster license holders to estimate spatially explicit landings and fishing effort when recreational fishers are most active—during the state's “Special Two‐Day Sport Season”, which takes place just before the opening of the commercial season, and during the first month of the regular recreational season, which coincides with the commercial season. From 1993 through 2002, fishing effort during the Special Two‐Day Sport Season has ranged from 60 000 to 112 000 person‐days, and landings have ranged from c. 112 to 255t. Both fishing effort and landings have varied without trend. Fishing effort during the regular season over the same period has ranged from 261 000 to 514 000 person‐days, and landings have ranged from 434 to 825 t. Fishing effort has shown a marginally statistically significant decreasing trend, the result of a progressive decrease in effort since 1999. The largest proportion of both fishing effort and landings was concentrated along the south‐east coast. Despite the recent decrease in landings, the proportion of total landings made by the recreational fishery has increased. From 1993 through 1998, the fishery was responsible for c. 30% of commercial landings; by 2001, that percentage increased to nearly 40%. Such a shift in landings away from the commercial trap fishery toward the recreational fishery was recognised as a potential but unintended effect of the ongoing management plan of restricting effort in the commercial trap fishery. Our 2001 surveys revealed that recreational lobster fishers spent more on a person‐day basis than the general visitor to the Florida Keys did, but less than those visitors using the region's coral reefs. Consequently, managers must establish management strategies that allow the coexistence of this resource's user groups and also incorporate the social and environmental concerns of nonuser groups.  相似文献   

15.
A coastal state benefits from importing the services of a distant water fishing nation (DWFN) fleet if the DWFN has a comparative advantage in exploiting the fishery, based on factors such as market access, costs or technology. The paper compares the activities of the Australian and Japanese vessels in the east coast tuna longline fishery and finds the Australian vessels receive higher prices, have higher costs and use a different technology from the Japanese fleet. These differences suggest a pattern of comparative advantage which can lead to Australia benefitting from importing the services of the Japanese fleet.  相似文献   

16.
Recent fuel price increases, together with future scarcity of fossil fuels and pollution have raised awareness about the efficient use of energy. Expenditure on marine fuel represents a significant component of the operational costs of the fishing fleets and, as a result, the profitability of the fishing fleets is very sensitive to fuel price variations. By assembling data from 54 fishing fleets around Europe, representing one fourth of the European Union (EU) fishing fleet in terms of vessel numbers and one third in terms of the volume of landings, the effects of the fuel price increase on the economic performance and the energy efficiency of the EU fleet, were estimated for the period 2002–2008. Results demonstrate declining trends in the economic indicators through the years, with a 33% reduction in profitability of the fleets since the beginning of the study. Most energy efficiency indicators, which featured a deteriorating trend over time, have improved their performance after 2004, when the first fuel price increase of the period was observed. However, results do vary across fleet segments.  相似文献   

17.
Climate variability and pelagic fisheries in northern Chile   总被引:5,自引:0,他引:5  
A time series analysis of long-term climate variability in northern Chile (18°21′–24°00′S) shows anomalies associated with the El Niño events and the longer warm period observed since 1976, followed by a cooling trend since mid 1980s. The succession of pelagic fisheries, anchovy (Engraulis ringens) and sardine (Sardinops sagax), occurring in this fishing zone was analyzed taking into account the landings, the CPUE abundance index, the fishing effort, and the environmental variables. The anchovy production model is a negative linear function of fishing effort and turbulence. For sardine, the production model is a negative linear function of fishing effort and a quadratic function of the sea surface temperature.An analysis of the relationship between recruitment, adult biomass and the environment shows that the annual recruitment of anchovy increases with turbulence intensity until wind speed reaches a value of 5.46 m s−1, decreasing for higher values. For sardine, the recruitment increases with turbulence intensity until 5.63 m s−1, stabilizing thereafter.It is deduced that the climatic variations associated to the El Niño events affect the abundance of coastal pelagic fishes, without forgetting the most likely effects upon its distribution and the fishing effort. However, it is the long-term variability that mainly affects the fishing activity.  相似文献   

18.
There is a need to better understand the linkages between marine ecosystems and the human communities and economies that depend on these systems. Here those linkages are drawn for the California Current on the US West Coast, by combining a fishery ecosystem model (Atlantis) with an economic model (IO-PAC) that traces how changes in seafood landings impact the broader economy. The potential effects of broad fisheries management options are explored, including status quo management, switching effort from trawl to other gears, and spatial management scenarios. Relative to Status Quo, the other scenarios here involved short-term ex-vessel revenue losses, primarily to the bottom trawl fleet. Other fleets, particularly the fixed gear fleet that uses pots and demersal longlines, gained revenue in some scenarios, though spatial closures of Rockfish Conservation Areas reduced revenue to fixed gear fleets. Processor and wholesaler revenue tracked trends in the bottom trawl fleet, which accounted for 58% of total landings by value. Income impacts (employee compensation and earnings of business owners) on the broader economy mirrored the revenue trends. The long-term forecast (15 years) from the Atlantis ecosystem model predicted substantial stock rebuilding and increases in fleet catch. The 15 year projection of Status Quo suggested an additional ∼$27 million in revenue for the fisheries sectors, and an additional $23 million in income and 385 jobs in the broader economy, roughly a 25% increase. Linking the ecological and economic models here has allowed evaluation of fishery management policies using multiple criteria, and comparison of potential economic and conservation trade-offs that stem from management actions.  相似文献   

19.
Peruvian anchovy (Engraulis ringens) stock abundance is tightly driven by the high and unpredictable variability of the Humboldt Current Ecosystem. Management of the fishery therefore cannot rely on mid- or long-term management policy alone but needs to be adaptive at relatively short time scales. Regular acoustic surveys are performed on the stock at intervals of 2 to 4 times a year, but there is a need for more time continuous monitoring indicators to ensure that management can respond at suitable time scales. Existing literature suggests that spatially explicit data on the location of fishing activities could be used as a proxy for target stock distribution. Spatially explicit commercial fishing data could therefore guide adaptive management decisions at shorter time scales than is possible through scientific stock surveys. In this study we therefore aim to (1) estimate the position of fishing operations for the entire fleet of Peruvian anchovy purse–seiners using the Peruvian satellite vessel monitoring system (VMS), and (2) quantify the extent to which the distribution of purse–seine sets describes anchovy distribution. To estimate fishing set positions from vessel tracks derived from VMS data we developed a methodology based on artificial neural networks (ANN) trained on a sample of fishing trips with known fishing set positions (exact fishing positions are known for approximately 1.5% of the fleet from an at-sea observer program). The ANN correctly identified 83% of the real fishing sets and largely outperformed comparative linear models. This network is then used to forecast fishing operations for those trips where no observers were onboard. To quantify the extent to which fishing set distribution was correlated to stock distribution we compared three metrics describing features of the distributions (the mean distance to the coast, the total area of distribution, and a clustering index) for concomitant acoustic survey observations and fishing set positions identified from VMS. For two of these metrics (mean distance to the coast and clustering index), fishing and survey data were significantly correlated. We conclude that the location of purse–seine fishing sets yields significant and valuable information on the distribution of the Peruvian anchovy stock and ultimately on its vulnerability to the fishery. For example, a high concentration of sets in the near coastal zone could potentially be used as a warning signal of high levels of stock vulnerability and trigger appropriate management measures aimed at reducing fishing effort.  相似文献   

20.
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