共查询到20条相似文献，搜索用时 31 毫秒
1.
Timothy J Emery Klaas Hartmann Bridget S Green Caleb Gardner John Tisdell 《Fish and Fisheries》2014,15(1):151-169
Successful individual transferable quota (ITQ) management requires a binding (constraining) total allowable catch (TAC). A non‐binding TAC may result in a shift back towards open access conditions, where fishers increasingly compete (‘race’) to catch their share of the total harvest. This process was examined by comparing fishing fleet behaviour and profitability in the Tasmanian southern rock lobster (Jasus edwardsii) fishery (TSRLF), Australia. Between 2008 and 2010, the TSRLF had a non‐binding TAC and effectively reverted to a regulated, limited‐entry fishery. Fishers' uncertainty about future profitability and their ability to take their allocated catch weakened the security characteristic of the ITQ allocation. The low quota lease price contributed to an increase in fleet capacity, while the more limited reduction in quota asset value proved an investment barrier, hindering the autonomous adjustment of quota towards the most efficient fishers. In the TSRLF, catch rates vary more than beach price and are therefore more important for determining daily revenue (i.e., price x catch rate) than market price. Consequently, fishers concentrated effort during times of higher catch rates rather than high market demand. This increased rent dissipation as fishers engaged in competitive race to fish to be the first to exploit the stock and obtain higher catch rates. The history of this fishery emphasizes the need for a constraining TAC in all ITQ fisheries, not only for stock management, but also to manage the security of the ITQ allocation and prevent unanticipated and undesirable changes in fisher behaviour and fishery profitability. 相似文献
2.
An age‐structured, population biology submodel and an economic submodel with vessel‐specific dynamics were applied to a demersal fishery in the North Aegean (NE Mediterranean) that consists of three main stocks: European hake Merluccius merluccius (L.), red mullet Mullus barbatus L. and striped red mullet Mullus surmuletus L. The Mefisto model is a bioeconomic simulation model through which the biological and economic submodels (disaggregated at the vessel level) are linked by means of a fishing mortality vector. Alternative management scenarios were built and tested based on input controls, and the performance of these strategies was examined against those of current policies. Three alternative management strategies were as follows: (1) reducing the coastal fisheries' fleet units; (2) limiting the effort level (days at sea) of the trawl fleets; and (3) changing the selectivity patterns of the trawl by increasing mesh size. The results show that for all three species, any of the three management measures (input controls) would be beneficial to both the stock and the fleets (over the medium and long terms) compared with the projections over time for the status quo. Improving the selectivity of the fishing gear proved to be more beneficial than limiting nominal effort, which was in turn more beneficial than decreasing coastal fleet size. 相似文献
3.
Trade‐offs in transitions between indigenous and commercial fishing sectors: the Torres Strait tropical rock lobster fishery 
下载免费PDF全文
下载免费PDF全文 T. Hutton E.I. van Putten S.D. Pascoe R.A. Deng É.E. Plagányi D. Dennis 《Fisheries Management and Ecology》2016,23(6):463-477
A bio‐economic model was developed to evaluate aspects of proposed quota‐based constraints vs the current effort control regulations for the tropical rock lobster, Panulirus ornatus, Fabricius, fishery in the Torres Strait (Australia/Papua New Guinea). The analysis integrates across biological, economic and social considerations. Model performance indicators have been chosen to reflect higher level policy objectives. The model simulation results indicate important trade‐offs. There is lower overall fleet total profit (across all the subfleets), lower fishery total value added and lower total employment if the fishery is quota‐constrained. This is due to an assumed rationalisation driven by incentives and current utilisation of capacity. The simulated re‐allocation of quota from the commercial non‐indigenous fleet allowing for greater potential indigenous fisher participation results in predicted increases in indigenous employment and would meet social objectives; however, due to limited capacity in the indigenous fleet, the simulated predicted lower catches led to lower total fishery profits and decreased total fishery value added within the supply chain. Investment in capacity could potentially offset this result. 相似文献
4.
Increasing use of spatial management tools in fisheries requires an understanding of fleet response, and in particular to where displaced fishing effort is likely to move. We develop a state‐dependent decision‐making model to address the spatial allocation of effort in an Australian tuna longline fishery. We assume that fishers have an economic objective in deciding where to fish, but that decisions in any period are also influenced by the remaining quota held at the time of the decision. Key features of the model include endogenous price dynamics, a moving stock and a competitive pool of different vessel types operating from different port locations. We utilize this model to illustrate fleet responses to marine reserves and limits on fishing effort. The results illustrate that the model framework provides advantages over statistically based models in that decisions made in response to the imposition of a reserve are not consistent with a proportional reallocation of effort. Rather, the stochastic dynamic model yielded an overall profit level of ～4% higher relative to scenarios with no reserve. Incorporating the opportunity cost of a quota into the model resulted in an optimal utilization of effort, in which effort was concentrated in time periods and locations yielding maximized profit. Under a low level of effort relative to the season length, the model indicated an overall profit level 43% greater than the highest obtained when the same level of effort was applied solely within any given quarter of the season. 相似文献
5.
A primary goal of ecosystem‐based fishery management is to reduce non‐target stock impacts, such as incidental harvest, during targeted fisheries. Quantifying incidental harvest has generally incorporated fishery‐dependent catch data, yet such data may be biased by gear non‐retention, observation difficulties, and non‐random harvest patterns that collectively lead to an impartial understanding of non‐target stock capture. To account for such issues and explicitly recognize the combined influence of ecological and harvest factors contributing to incidental capture within targeted fisheries, we demonstrate a probabilistic modelling framework that incorporates: (i) background rates of target and non‐target stock co‐occurrence as the primary ecological basis for incidental harvest; (ii) the probability of harvesting at localities exhibiting co‐occurrences; (iii) the probability of selecting for non‐target species with fishery gear; and, (iv) as a function of harvest effort, the overall probability of incidental capture for any non‐target stock contained in the species pool available for harvest. To illustrate application of the framework, simulation models were based on fishery‐independent data from a freshwater fishery in Ontario, Canada. Harvest simulations of empirical stock data indicated that greatest species‐specific capture values were over 4000 times more likely than for species with lowest values, indicating highly variable capture probabilities because of the combined influence of stock heterogeneity and harvest dynamics. Estimated bycatch–effort relationships will allow forecasting incidental harvest on the basis of effort to evaluate future shifts in fishing activity against specific ecosystem‐based fishery management objectives, such as reducing the overall probability of bycatch while maintaining target landings. 相似文献
6.
Paolo Sartor Pierluigi Carbonara Sandro Cerasi Giuseppe Lembo Maria Teresa Facchini Alessandro Lucchetti Rosaria Felicita Sabatella Claudia Musumeci Walter Zupa Maria Teresa Spedicato 《Fisheries Management and Ecology》2019,26(6):661-673
Small‐scale driftnets (SSDs) have been historically used in the Mediterranean without major environmental concern. The introduction of large‐scale driftnets caused unwanted catches of protected species. Specific regulations were therefore issued in European waters, culminating in a proposed moratorium on SSDs. This study aimed to characterise the SSD fishery targeting anchovy (menaide), evaluating its environmental sustainability, economic performance and social relevance. In 2013, a survey by interviews, logbooks and observers on board assessed the order of magnitude of this fishery in terms of fishing capacity and activity, volume of landings and revenues. The menaide fleet consisted in 60 vessels <12 m overall length, moored in little harbours in southern Italy. These nets are highly selective: the target species, European anchovy, Engraulis encrasicholus (L.) and sardine, Sardina pilchardus (Walbaum), dominates the catches, while discards are negligible. The anchovies caught are of high quality and large size; the high prices support fish processing by local factories. Moreover, the results of a SWOT analysis demonstrated that replacing SSDs with a semi‐industrial fishery, like purse seining, would increase impacts on the ecosystem, and a loss of socio‐economic opportunities for several coastal villages. These findings support the option of keeping SSDs operating, in the framework of specifically oriented management measures. 相似文献
7.
Does marine fish farming affect local small‐scale fishery catches? A case study in the NW Mediterranean Sea 下载免费PDF全文
下载免费PDF全文 Fish farms have been shown to aggregate large numbers of wild fish in their surroundings. Although little is known about how this affects the local fishery, two hypotheses have been put forward; a trapping and a protecting effect on wild fish. This study provides the first monitoring of commercial and recreational fishing activity at a fish farm. We assessed the effect on the small‐scale fishery analysing the differences between fishing in farm proximity and away from the farm (in terms of catch rate, income and catch composition). Moreover, we estimated the biomass removal from fishing activities by farm employees inside the farm. The study was conducted from January 2011 to June 2012 at a Gilthead seabream farm in the NW Mediterranean. The findings revealed a relevant amount of commercial and recreational fishing effort in farm proximity. Yet, the results showed no benefit or difference of fishing in close proximity to the farm compared with areas away from the farm. Thus, we conclude that farm‐aggregated fish are protected from the commercial fleet by the farm leasehold area, but remain vulnerable to hidden fishing practices inside the farm, where farm employees harvest more than 4 t of wild fish annually. 相似文献
8.
Paolo Casale 《Fish and Fisheries》2011,12(3):299-316
Sea turtle by‐catch data in the Mediterranean were reviewed and analysed with fishing effort. The results indicate over 132 000 captures per year, with probably over 44 000 incidental deaths per year, while many others are killed intentionally. Small vessels using set net, demersal longline or pelagic longline represent most of the Mediterranean fleet and likely cause more incidental or intentional deaths than large vessels typically using bottom trawl or pelagic longline. When interactions, mortality, intentional killing, size (a proxy for reproductive value) and turtle populations are considered, results indicate that Mediterranean green (Chelonia mydas) and loggerhead turtles (Caretta caretta) are more affected (i) by fishing gears such as bottom trawlers, demersal longlines and set nets, (ii) by small‐scale fisheries, and (iii) by fishing in the eastern basin. Although small‐scale fisheries should be the priority target, available measures are easier to implement on the fewer large vessels. Moreover, these measures are few, and they are not implemented yet, while others should still be tested for the Mediterranean fisheries. Thus, measures for reducing captures or mortality through changing gear‐specific characteristics may help, but probably a more holistic conservation strategy aimed to an ecosystem‐based fishery management for a sustainable fishing would be the only solution for the long‐term survival of Mediterranean Sea turtle populations and their habitats. Small‐scale fisheries should manage marine resources, including turtles, in a responsible and sustainable way. Turtles may not only benefit from but can also help this process if their non‐consumptive value is fully recognized. 相似文献
9.
Ian G. Baird 《水产资源保护:海洋与淡水生态系统》2006,16(5):517-532
- 1. Probarbus jullieni and Probarbus labeamajor are two of the largest carps in the Mekong River Basin, each reaching a maximum weight of about 70 kg. P. jullieni is listed in Appendix 1 of the Convention on the International Trade in Endangered Species, and both are listed on the IUCN Red List of Threatened Species, the first as ‘endangered’ and the second as ‘data deficient’.
- 2. Six years of quantitative monitoring of a large‐meshed gill net fishery for Probarbus just below the Khone Falls in Khong district, Champasak province, in southern Laos shows that 78% of the overall catch is comprised of Probarbus, with P. jullieni making up 65% of landings.
- 3. Over the 6‐year period catches of Probarbus declined significantly. However, catch‐per‐unit effort statistics do not indicate that the fishery is in decline, although fishers are convinced that real stock reductions are a large part of the reason for catch declines and decreases in fishing effort.
- 4. A number of ecological and social factors are affecting the number and quality of gill nets in use, the length of fishing seasons, and gill net efficiency, making it difficult to compare catch‐per‐unit effort between years.
- 5. There has been a shift from using large‐meshed gill nets for catching Probarbus to targeting smaller species using gill nets with smaller mesh‐sizes. This is an example of the ‘fishing down’ of a Mekong fish community, in which large long‐lived species are the first to be affected by heavy fishing pressure.
10.
11.
Sixty‐two years of voluntarily collected angling logbook data from a large natural Danish lake were used to study variation in pike, Esox lucius L., CPUE (catch per unit effort), expressed as no. of captured pike per boat trip, as an index of stock size. Pike CPUE was positively related to pike release rate by anglers and negatively affected by certain commercial fishers. The stocking of young‐of‐the‐year pike and a fishery‐dependent index of perch, Perca fluviatilis L., abundance (which may be pike prey or predator depending on size) did not correlate with pike CPUE. Analyses of the size distribution of pike, based on sizes of annual record trophy pike captured by anglers, confirmed the negative impact of commercial pike fishing and revealed a positive influence of air temperature. It is concluded that high‐quality angler logbooks that record effort and catch can be a cost‐effective tool to inform lake fisheries management by revealing long‐term population trends. Further, state space modelling, a statistical technique not yet seen in recreational fisheries science, is recommended as a tool to model proxies for population dynamics from angler logbook data. 相似文献
12.
John Cotter 《Fish and Fisheries》2010,11(2):210-219
I summarize the total allowable catch (TAC) fishery management system, which forms part of the European Common Fisheries Policy (CFP) as complicated, inaccurate and ineffective. Total allowable effort (TAE), i.e. limits on fishing capacity and days‐at‐sea, provides a simpler, readily enforceable control to protect all species affected by a fishery. Fishing capacity of vessels in each region‐gear fleet could be capped through limits on engine power, gear, crew, and fittings, and/or reducing allowances of days‐at‐sea for large, powerful vessels. Two basic, fishery‐dependent indicators are put forward to assess sustainability of a fishery dependably even in the absence of fishery‐independent data. One is socio‐economic, the other is ecological. Fishery working groups within each marine region would recommend a TAE to sustain their fishery while also protecting the most critically affected species or processes. Regional working groups would supervise a consistent approach across the different fisheries in their region. A pan‐European group would set policy, implement external agreements, set rules for trading TAE if necessary and harmonize fishing opportunities across regions. To ease negotiations on TAEs with the fishing industry when an ecosystem needs to recover, I propose compensation payments funded by re‐direction of existing CFP subsidies that promote fishing. 相似文献
13.
Anna Maria Go
dziejewska Andrzej Robert Skrzypczak Jacek Kosza&#x;ka Magdalena Bowszys 《Fisheries Management and Ecology》2020,27(3):279-291
The use of artificial water bodies for angling is a popular practice, especially in industrial and urbanised areas where natural water bodies are lost. In this study, the zooplankton structure dynamics and water quality at three strip mine drainage system reservoirs were assessed with different types of recreational fishery exploitation: K1—intensive angling using the catch‐and‐release model, K2—lowest angling pressure and higher share of predatory fishes and K3—moderate fishing, that is limiting groundbait quantities and eliminating non‐predatory fishes by anglers. The null hypothesis tested was that recreational fishing does not affect the biotic and abiotic conditions of reservoirs. The significance of each environmental variable was tested using redundancy analysis (RDA). The highest nutrients and chlorophyll a concentration, turbidity level and organic matter content occurred in K1. Zooplankton diversity was the lowest under these conditions; protozoa and larval stages of copepods dominated. In reservoirs where sustainable fishing was implemented (K2, K3), trophic parameters of water were lower, on average, by 25%, turbidity by 30%, and productivity by 35–70%. Zooplankton diversity was significantly higher; rotifers and small cladocerans dominated. The choice of recreational fishing model determines the functionality and biological potential of the reservoir. 相似文献
14.
Growth overfishing in the brown shrimp fishery of Texas, Louisiana, and adjoining Gulf of Mexico EEZ
Growth overfishing in the brown shrimp, Farfantepenaeus aztecus, fishery in inshore (estuarine) and offshore (Gulf of Mexico) territorial waters of Texas and Louisiana, and adjoining waters of the United States’ (U.S.) Exclusive Economic Zone (EEZ), and its potentially detrimental economic consequences to the harvesting sector, have not been among major concerns of Federal and State shrimp management agencies. Three possible reasons include (1) environmentally influenced variations in recruitment that cause wide fluctuations in annual landings, which tend to obscure effects of fishing, (2) competition between inshore and offshore components of the harvesting sector, and (3) partitioning of management jurisdiction among a Federal council and two State agencies. Wide variations in landings led to beliefs that high levels of fishing mortality were tolerable and recruitment overfishing was of no major concern. This encouraged somewhat laissez-faire management approaches that allowed fishing effort to increase over the years.Our objectives were to determine whether growth overfishing occurred in this fishery during 1960–2006, and whether and how decreases in size of shrimp within the landings, in response to increases in fishing effort, affected inflation-adjusted annual (calendar year) ex-vessel value of the landings, i.e., their value to the harvesting sector. Growth overfishing occurred in the early 1990s, and then abated as fishing effort declined due to rising fuel costs and competition from imported shrimp. However, inflation-adjusted annual ex-vessel value of the landings peaked in 1985, prior to growth overfishing.Management actions implemented in 2001 for Texas’ territorial waters, and in the EEZ off Texas and Louisiana in 2006, should limit future fleet expansion and increases in fishing effort, thereby reducing the chances of growth overfishing and its potentially detrimental economic impacts on the harvesting sector. Growth overfishing should be included among the guidelines for future management of this brown shrimp fishery. 相似文献
15.
16.
J. R. Post 《Fisheries Management and Ecology》2013,20(2-3):99-110
Are recreational fisheries resilient to harvest or prone to collapse? This paper reviews research published since that question was posed by Post et al. (2002, Fisheries 27 , 6–17). A number of patterns and processes have been identified that suggest understanding the risk of collapse requires knowledge of the fishing effort response, degree of depensation in the fishery and the life history of the harvested species. Processes involving the behaviour of fish, behaviour of anglers and management responses to declining quality can all impact the degree of resilience of recreational fisheries and their risk of collapse. The spatial context of an individual fishery can be important as they are often embedded in lake districts and joined by mobile anglers so their local dynamics are not independent from other fisheries. Typical regulations that restrict the behaviour of individual anglers in open‐access fisheries can provide some resilience but cannot prevent collapse if the fishing effort is too high. Many uncertainties remain related to the occurrence and intensity of the key processes and therefore adopting an adaptive experimental management approach might be the most useful approach to minimise the risk of collapse in recreational fisheries. 相似文献
17.
18.
Alexander Filous Robert J. Lennox Paige Eveson Raphael Raveino Eric E. G. Clua Steven J. Cooke Andy J. Danylchuk 《Fisheries Management and Ecology》2020,27(2):200-214
Fisheries management requires knowledge on the population dynamics of exploited stocks. To that end, the present study used a mark–recapture approach to characterise the population demographics of roundjaw bonefish Albula glossodonta (Forsskål) and their interaction with a data‐limited fishery on Anaa Atoll in the Tuamotu Archipelago of French Polynesia. Over the course of the study, 2,509 bonefish were tagged and 12.3% were recaptured. The L∞ of bonefish was estimated at 71 cm fork length (FL) with a K of 0.17, based on changes in FL between capture events. Artisanal fish traps located in the migratory corridors of the atoll accounted for 94% of recaptures and these movements occurred during the waning moon. Fishing mortality increased as bonefish reach sexual maturity, recruiting to the trap fishery at age 4 with the onset of spawning behaviour. Bonefish abundance between ages 3 and 5 was estimated to be 29,079 individuals. This case study demonstrated the utility of mark–recapture in filling knowledge gaps that impede the management of data‐limited fisheries. Ultimately, these results supported the creation of an Educational Managed Marine Area and the resurgence of rahui (seasonal closure) to manage this fishery. 相似文献
19.
Bechir Saidi Khaled Echwikhi Samira Enajjar Sami Karaa Imed Jribi Mohamed N. Bradai 《水产资源保护:海洋与淡水生态系统》2020,30(6):1172-1181
- This study evaluated the circle hook use as a tool for shark management in the pelagic longline fishery in the Gulf of Gabès.
- The usual J‐hook No. 2 with 10° offset, which has been traditionally used by the fishery, was compared to the 18/0 non‐offset circle hook in an alternating fashion along the main line. In total, 22 experimental longline sets were deployed through the shark fishing seasons of 2016 and 2017 to examine the effects of hook types on the catch composition, the catch rates, the hooking location, and the status at haulback.
- The catch composition differed significantly among hook types. Moreover, an overall increase in catch rates for the main species, the sandbar shark Carcharhinus plumbeus, and the shortfin mako shark Isurus oxyrinchus, was observed when using circle hooks.
- There was no size‐selective effect of circle hooks for the common species. The circle hooks were not effective at reducing at‐haulback mortality of sandbar shark. Conversely, shortfin mako and smooth‐hound shark Mustelus mustelus showed significantly lower relative mortality at haulback with circle hooks than with J‐hooks. Furthermore, circle hooks were more frequently hooked externally than the J‐hooks for the three shark species.
- Results demonstrated that the use of 18/0 non‐offset circle hooks in the pelagic shark longline fishery can reduce mortality at haulback for some species without any benefit for the dominant species, the sandbar shark.
- Overall, it is difficult to promote the adoption of the use of circle hooks as a management measure in this specialized fishery. Management measures focusing on fishing effort controls, fishing closures in critical habitats, and size limits could have significant benefits for the conservation of shark species and may help to improve the sustainability of the shark fishery in the Gulf of Gabès.
20.
The Irish otter trawl fleet operates in a complex multi-species multi-gear fishery, spanning a wide geographic area, and involving around 275 trawlers. Factorial and clustering methods were applied to 2003 fishing trip data to define thirty-three métiers. Definitions were based on six trip characteristics taken from logbooks, namely: fishing gear, mesh size, vessel length, species composition, area, and month. Métiers exploiting demersal species or species groups are characterised by single vessel bottom otter trawls, typically with mesh sizes of 70 mm or more, operating year round. This includes nine Nephrops dominated métiers highlighting the importance of this species to the fleet. Many demersal métiers are characterised by groups of species, such as mixed whitefish or slope species. Métiers exploiting pelagic species are often focussed on single species, and are typically seasonal, mid-water trawling (often paired) with mesh sizes less than 70 mm. Pelagic métiers account for the majority of landings by over an order of magnitude in several cases. Demersal métiers account for the majority of fishing trips and effort, (primarily Nephrops métiers), and vessels (primarily mixed species métiers). The new métier definitions were found to be appropriate remained relevant despite declining fleet landings and effort between 2003 and 2006. Species compositions within these métiers have generally remained similar to the proportions defined in 2003. These robust métier definitions present opportunities to improve fisheries sampling, assessment and management. Although métiers pose complexity challenge for such applications they can be used the building blocks for appropriate management units. 相似文献