首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
A total of 248 roving creel surveys along the length of the Berg River Estuary, in the Western Cape, South Africa, recorded 626 shore-angler and 88 boat-angler outings over the period December 2002–November 2005. Catch-and-effort information was obtained from catch inspections with 360 handline and 246 rod-anglers. Average total annual linefishing effort was estimated at 449 ± 29 (mean ± SE) boat-angler days, 1 299 ± 118 recreational shore-angler days and 1 394 ± 57 subsistence (handline) shore-angler days. The estimated total shore-based linefish catch (excluding boat-based catches) from the estuary for the years 2004 and 2005 was 37 231 ± 1 326 fish and 26 938 ± 706 fish (approximately 8 t and 7 t) respectively. Compared with other estuaries along the South African east coast where angler catches have been surveyed, species diversity in catches from the cool-temperate Berg River Estuary was low, with only 15 species caught, of which three, elf Pomatomus saltatrix (56%), harder Liza richardsonii (31%) and carp Cyprinius carpio (11%), dominated the catch. Average linefish catch per unit effort of most species increased significantly in the two years subsequent to the closure of the long-existing commercial gillnet fishery in March 2003. Length frequency distributions revealed significant increases in the average size and an increased contribution of larger size class elf and harder to the linefish catch over the monitoring period, suggesting a degree of recovery of the estuarine icthyofauna after more than a century of intensive gillnet fishing.  相似文献   

2.
Southern rock lobster (Jasus edwardsii) support significant commercial and recreational fisheries in Tasmania, Australia. Since the mid 1990s the number of persons holding recreational lobster licences increased by over 80%, with c. 15 500 persons licensed in 2002/03. Assessment of the recreational fishery has been undertaken periodically since 1996 using a telephone‐diary survey method. The fishery was concentrated off the south‐east and east coasts of Tasmania and characterised by strong seasonality in catch and effort, which peaked markedly early in the fishing year (November‐January). Although pots were the most popular fishing method, daily catch rates by divers were more than double those for pots. Divers selectively harvested larger lobsters than those taken by pots and more frequently attained the daily bag limit of 5 lobsters. The estimated recreational harvest increased significantly since 1996/97 and in 2002/03 effectively reached a management trigger level of 10% of the total allowable commercial catch, flagging a review of recreational management arrangements.  相似文献   

3.
St Lucia is one of the largest estuarine systems in Africa, and attracts thousands of anglers each year. Catchcard data from the National Marine Linefish System for the years 1986–1999 were analysed to determine catch composition, catch per unit effort (cpue) and seasonality of catches by recreational anglers. Because not all anglers completed catch cards, estimates of total catch were made using additional data on the number of private boat outings, the number of boat trailers at boat slipways and the number of boats recorded entering the campsite gates during 1992 and 1993. In all, 27 fish families, constituting 55 species, were recorded by recreational anglers. Dusky kob Argyrosomus japonicus, spotted grunter Pomadasys commersonnii, perch Acanthopagrus berda, Natal stumpnose Rhabdosargus sarba, springer Elops machnata and mini-kob Johnius dorsalis were the most prominent species caught in terms of numbers and mass. Catch rates expressed numerically (fish angler?1 h?1) peaked during the summer and early winter. However, in terms of mass, catch rates peaked during late winter and spring, when there were increased landings of large dusky kob. Fluctuations in cpue were linked to salinity and estuary mouth conditions (i.e. mouth closure). Despite annual fluctuations in cpue, regression analysis revealed an overall downward trend for the dominant species (dusky kob and spotted grunter) and a gradual increase for stumpnose, perch and springer, but with the exception of stumpnose, these trends were not significant. Socio-economic aspects of the fishery were also investigated by conducting an independent boat-angler survey. The value of the recreational fishery, in terms of accommodation and direct angler expenditure, was estimated to be in the region of R9 million during 1992. Angler attitudes towards fishing regulations were positive and anglers generally had a good knowledge of the regulations for target species. Based on this assessment, a number of suggestions are made regarding the future management of the recreational fishery at St Lucia.  相似文献   

4.
White stumpnose Rhabdosargus globiceps is the main target of the linefishery in Saldanha Bay. Increased fishing pressure over the last three decades, particularly by the recreational sector, has led to concerns regarding sustainability of the local white stumpnose stock. The fishery was exceptionally productive between 2006 and 2008, with an estimated annual catch of 141.2 tonnes (t). Only 3% of boat outings surveyed were commercial boats targeting white stumpnose, yet this sector accounted for 39.3 t (31%) of the average annual catch. The recreational boat sector accounted for most of the catch (70.0 t), and the recreational shore sector the least (31.9 t). Commercial boat catch per unit effort (CPUE; 3.7 fish angler–1 h–1) was more than 10 times that of recreational boats (0.3 fish angler–1 h–1). White stumpnose catch length-frequency differed significantly (p < 0.01) between the fishing sectors, with the commercial sector retaining larger fish (34.7 cm [SD 5.9]) than the recreational boat (33.9 cm [SD 5.9]) and shore (30.4 cm [SD 5.8]) sectors. A decline in commercial CPUE (2000–2015) of approximately 40% and a concomitant severe decline (>95%) in survey data for juvenile white stumpnose CPUE (2007–2016) indicate that the current rate of exploitation is not sustainable. Recovery of the white stumpnose stock will require a decrease in fishing mortality. Possible management regulations include sector-specific effort limitations, extending the ‘no take’ marine protected area, reducing the recreational-sector bag limit to 5 fish person–1 day–1, implementing a commercial-sector bag limit, and increasing the minimum size limit to 30 cm TL.  相似文献   

5.
  相似文献   

6.
Management of recreational fisheries cannot be based on biological and stock assessment data alone but needs to include appropriate social aspects (including knowledge, attitudes and behaviour) of anglers within the fishery. The primary purpose of this study was to evaluate and complement existing recreational fisheries research, through the analysis of demographic and psychographic angler attributes collected from two independent, shore-based snapshot monitoring surveys conducted on the KwaZulu-Natal (KZN) coastline of South Africa, in 1994–1996 and 2009–2010. Results show significant changes between the two survey events in the demographics of anglers (including ethnic composition, age distribution, years of fishing experience and employment status) participating in the KZN shore-based linefishery. Traditional management regulations (minimum size limits, daily bag limits and closed seasons), though appearing to have support, have had limited effectiveness, based on the increased levels of admitted non-compliance and poor knowledge of regulations for target species. Anglers in both surveys believed that catches had declined over the years, with overfishing being the most common reason given. The results are discussed in the context of changing management practices in the KZN recreational shore-based linefishery. The implications of changes in fisheries management policies and responsibilities along the KZN coast are highlighted.  相似文献   

7.
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   

8.
Indicators of abundance for American lobster (Homarus americanus) based on 8 years of trap catch rates (catch‐per‐unit‐effort, CPUE) were evaluated. Volunteer harvesters recorded count, sex and size of lobsters captured in standard traps on a daily basis during the fishing season in coastal Nova Scotia, Canada. We examined the extent to which standardised CPUEs of prerecruits predict the future catches of legal sizes and explored spatial patterns in the abundance of lobsters of different size and reproductive status. The standardised CPUE of prerecruits was correlated with legal size catches in only one of five areas examined. This area had a strong signal of incoming recruitment. Improving the capacity of prerecruit CPUE for predicting legal size catches several years later most likely lies with model incorporation of variables associated with catchability. The spatial distribution of catch rates showed that the area with the highest historical landings per unit area also had the highest relative abundance of prerecruits. The spatial distribution data point to further areas of research related to recruitment processes in lobster in coastal Nova Scotia.  相似文献   

9.
The Namibian linefishery is a multisector fishery, with recreational and commercial sectors targeting overlapping species. Prior to 1990, catch data were recorded for the boat sector, but little research was done on the population dynamics of any of the species. Hence, none of the stocks were assessed owing to the lack of parameter estimates for fisheries modelling. Current management regulations for the Namibian linefishery are therefore not based on scientific investigations but, for historical reasons, were adapted from South African legislation for similar species. From 1994, linefish research in Namibia focused on the life history and population dynamics of silver kob Argyrosomus inodorus and West Coast steenbras Lithognathus aureti, important species in both commercial and recreational sectors. A roving-roving creel survey was used to determine effort and catches of recreational shore-anglers. Both species were assessed using yield-per-recruit models. Based on the results, reduced daily bag limits and the implementation of size limits for the recreational sector were proposed. For the commercial sector, the introduction of a total allowable catch would seem to be the best option. Results from an economic survey indicated that the recreational sector earns six times more for the country annually than the commercial sector.  相似文献   

10.
Over the last several years, significant regulatory changes related to Pacific halibut Hippoglossus stenolepis have occurred in the for-hire recreational charter boat fishing sector in Alaska. In addition to limited entry restrictions and adoption of a catch sharing plan that provides a formal means of determining allocation between the commercial and charter boat fishing sectors, more restrictive harvest regulations were placed on anglers fishing from charter boats. This article provides insights into how the value anglers place on charter boat fishing is affected by these regulations, principally bag and size limits. Such information is helpful in assessing the trade-offs in economic benefits associated with different regulatory tools used to manage angler harvest levels. Stated preference choice experiment data from a 2012 survey are analyzed using a panel rank-ordered mixed logit model to estimate the economic value, or willingness to pay (WTP), non-resident anglers place on saltwater charter boat fishing trips in Alaska and to assess how changes in characteristics of fishing trips, particularly harvest restrictions related to Pacific halibut, affect this value. The model specification accounts for a wide array of size and bag limit restrictions that have been recently implemented or are under consideration by Pacific halibut fishery managers. The results indicate that very strict harvest restrictions have the effect of driving WTP to zero, while allowing at least one (potentially) large fish to be caught is valuable to anglers. The results also suggest that WTP for fishing trips with bag limits that allow two or more fish to be harvested with no size restrictions on the first fish harvested are not statistically different from the value for trips for larger bag limits or for the case where all the fish in the limit can be any size. This suggests that fishery managers can restrict the size of the second fish in a two-fish bag limit and still maintain economic values for fishing trips.  相似文献   

11.
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   

12.
Understanding the socio-economic drivers underpinning fishers' decisions to target elasmobranchs is considered vital in determining sustainable management objectives for these species, yet limited empirical data is collected. This study presents an overview of elasmobranch catch, trade and socio-economic characteristics of Zanzibar's small-scale, artisanal fishery. The value of applying this information to future elasmobranch fisheries policy is demonstrated. In August 2015, interviews were conducted with fishers (n = 39) and merchants (n = 16) at two landing sites, Kizimkazi-Dimbani and Mkokotoni, along with the main market site in Stone Town. Additionally, elasmobranch catches were recorded across the same locations between June and August 2015. Elasmobranchs were listed as target species by 49% of fishers interviewed. Whilst most fishers (n = 30) stated that 76–100% of their household income came from fishing, there was variation in how elasmobranch catch and trade contributed. One-third of fishers (n = 36) that caught and sold elasmobranchs reported that 41–60% of their income came from elasmobranch catch. However, for some fishers (n = 8) elasmobranch catch represented 0–20% of their income, whilst for others (n = 4) it represented 81–100%. Differences in fisheries income and elasmobranch price could be attributed to several interacting factors including season, weather, fishing effort, fishing gear, target catch and consumer demand. Further, elasmobranch price was influenced by size and species. The study revealed information on catch, trade, markets and socio-economy that is important for future research, conservation and management of elasmobranchs and fisheries in Zanzibar. The methods utilised have potential for broader application to understudied, artisanal elasmobranch fisheries in the western Indian Ocean.  相似文献   

13.
The western rock lobster fishery is one of the most valuable single‐species fisheries in Australia, valued at AU$300 million per year. The impact of environmental factors such as lunar cycle and swell on the daily catch rate of the western rock lobster (Panulirus cynus) is of particular interest in the stock assessment and management of the fishery. The variation in daily catch rates was examined for two periods (migrating period November‐January, non‐migrating period February‐June), at different depths in three management zones for three categories of lobster (undersize, legal size, and setose). Regression and transfer function models for relationships between catch rates and environmental data were considered and compared. The lunar cycle has a significant impact on the daily catch rates with c. 30% lower catch rate during the full moon and c. 20% higher catches near the new moon. This impact occurs mainly during the non‐migrating period both in deep water (40–100 m) and shallow water (<40 m). The swell on the day before fishing was also shown to be significantly related to the catch rate with an increase of c. 10–15% for an increase in swell from light to moderate or moderate to high. These environmental factors can be used to standardise catch rates to provide an improved abundance index for stock assessment. Also, management closures are being considered for 3–5 days over the low catch rate, full moon period to reduce fishing costs and lower fishing effort.  相似文献   

14.
Information about stakeholder aspirations is a fundamental requirement for ecosystem-based management, but the detail is often elusive, and debates may focus on simplistic opposing positions. This is exemplified by the Antarctic krill fishery, which, despite a current operational catch limit equivalent to just 1% of the estimated biomass and actual annual catches much lower than this, is the subject of a high-profile debate framed around ambiguous concepts such as sustainability. Q methodology was applied to explore the detailed views of representatives of three stakeholder sectors (the fishing industry, conservation-focused non-governmental organisations (NGOs), and scientists from seven countries involved in research on the krill-based ecosystem). The analysis distinguished two clear groupings, one of which included the views of all NGO participants while the other included the views of fishing industry participants and a subset of the scientists. Key differences between the groups included the priority given to different management measures, and to continued commercial fishing. However, the results also revealed considerable overlap between viewpoints. Both groups prioritised the maintenance of ecosystem health and recognised the importance of defining management objectives. Also, neither group prioritised a decrease in catch limits. This suggests that most participants in the study agree that management should improve but do not perceive a major problem in the ecosystem's ability to support current catch levels. Cooperation to identify shared management objectives based on stakeholder aspirations for the ecosystem might enhance progress, whereas polarised discussions about preferred management measures or ambiguous concepts are likely to impede progress.  相似文献   

15.
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   

16.
This study investigated the support for, and potential impacts of, alternative management measures to address declining fish stocks in the Breede River estuary. A survey of residents and visitors was carried out during 2011–2012. Angling was the most important attraction of the estuary, and accounted for at least R 25 million in annual expenditure in the area. The majority of recreational anglers were concerned about the status of fish stocks and felt that additional regulations were necessary. There was greatest support for banning the trolling of artificial lures, and majority support for a closed area and an upper size limit for one of the main species targeted – the dusky kob Argyrosomus japonicus. The options of a night ban on fishing and a closed season received little support. Ratings of alternative scenarios suggested that anglers were more sensitive to fish abundance than to regulations. Modelled results showed that regulations resulting in increased abundance of fish, and large A. japonicus in particular, would have a positive impact on angling value of the estuary, whereas further declines in fish stocks would result in a decrease in expenditure in the area.  相似文献   

17.
Marine Recreational Fishing (MRF) is an important activity in Europe, with 9 million fishers and generating annually € 6 billion in direct expenditures. However, there is a lack of data and understanding of MRF in Europe, particularly in Southern countries, which prevents a number of fish stocks from being effectively assessed and managed. In November 2016, a participatory workshop on MRF was held in Vigo (Spain) to identify challenges and opportunities for data collection, and to diagnose key research gaps and management issues for MRF in the Southern European Atlantic. Experts from a wide range of disciplines (researchers, policy makers, fisheries managers and commercial and recreational fishers) highlighted that the management of MRF is a challenge due to complex and dispersed legal frameworks, with multiple administrations involved, and overlapping uses of space with commercial fishing, aquaculture, navigation and tourism, among others. The lack of strong and representative fishing associations hampers research and management initiatives. Effective communication between recreational fishers, researchers and fisheries managers is also lacking. Despite the ecological, social and economic relevance of MRF, there is no systematic and comprehensive collection of information on fishing effort, recreational catches, expenses, social profile and access conditions of European recreational fishers. These data would be useful to avoid biases in the assessment of recreational fisheries due to the great diversity of ecosystems, species and typologies of users. Strategic recommendations and research priorities were also identified to address knowledge gaps and are discussed in the context of the management of MRF across Europe.  相似文献   

18.
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   

19.
To understand the confounding fishing effect and physical influence on fish production, catch time series in the East China Seas were analyzed. Principal component analysis partitioned 18 catch time series into interannual trends and variations. While the trends were attributed to growth in fishing effort, variations in catches were related to precipitation and monsoon wind speed. Correlations of catch variations with the physical variables suggest that land-based runoff and monsoon circulation of the diluted coastal water masses are the physical forces dominating catch variability and the influences are largely through the associated nutrient supply on primary production. Runoff inputs nutrients to the coastal ecosystem, while monsoons drive their distribution. Offshore diffusion of the coastal water masses by the summer monsoon increases distribution and efficiency of nutrients and has a positive effect on fish production. Southerly transport of coastal currents alongshore by the winter monsoon confines nutrient distribution and induces nutrient loss from the northern waters. This process reduces overall and northern production, but increases production to the south. A long-term variation in catches was identified, which corresponds to a trend in the local winter monsoon as well as large-scale atmospheric changes. Prediction of the catch variation by the local wind speed suggests that large-scale atmospheric circulation determines the trend in the local winter monsoon, and the local winter monsoon that drives nutrient distribution should be directly responsible for the long-term variation of fish production in the East China Seas.  相似文献   

20.
Given the focus on protecting natural assets in the Great Barrier Reef Marine Park in Australia, it is important for managers and policy makers to understand the value of recreational fishing in the area, and how changes in management may affect those recreational values. Travel cost methods were used to estimate the value of recreational fishing in the Capricorn Coast in Central Queensland using data from on-site surveys conducted at boat ramps. The study also uses contingent behaviour models to estimate the change in the value of recreational fishing as conditions vary. Results indicate that there are high values associated with recreational fishing activity along the Capricorn Coast, and that the demand for recreational fishing is inelastic and that values are relatively insensitive to changes in catch rates.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号