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排序方式: 共有189条查询结果,搜索用时 281 毫秒
41.
Ashley J. Williams Aaron C. Ballagh Gavin A. Begg Cameron D. Murchie Leanne M. Currey 《Continental Shelf Research》2008
The reef line fishery (RLF) in eastern Torres Strait (ETS) is unique in that it has both a commercial indigenous sector and a commercial non-indigenous sector. Recently, concerns have been expressed by all stakeholders about the long-term sustainability of the fishery. These concerns have been exacerbated by the lack of detailed catch and effort information from both sectors, which has precluded any formal assessment of the fishery. In this paper, we characterise the harvest patterns and effort dynamics of the indigenous and non-indigenous commercial sectors of the ETS RLF using a range of data sources including commercial logbooks, community freezer records, voluntary logbooks and observer surveys. We demonstrate that bycatch is a significant component of the catch for both sectors and identify substantial differences in harvest patterns and effort dynamics between the sectors. Differences between sectors were observed in species composition and spatial and temporal patterns in catch, effort and catch per unit effort. These results highlight the inherent variation in catch and effort dynamics between the two commercial sectors of the ETS RLF and provide valuable information for the development of future assessments and appropriate management strategies for the fishery. The more reliable estimates of harvest patterns and effort dynamics for both sectors obtained from observer surveys will also assist in resolving issues relating to allocation of reef fish resources in Torres Strait. 相似文献
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《Marine Policy》2016
The management of invasive species can be facilitated by public participation. The drivers of public involvement and success at invasive removal in tournaments (derbies) to catch Indo-Pacific lionfish (Pterois volitans/miles) in the Western Atlantic were examined. Information on 69 lionfish derbies held in the wider Caribbean region from 2010 to 2015 was compiled. Derbies attended mainly by artisanal fishers reported lower catches but higher participation than derbies dominated by recreational divers or attended by a mixed public. As predicted, the number of lionfish caught increased with effort and with time since lionfish were established in an area. In contrast, participation was best predicted by national wealth (GDP per capita) and number of local dive shops. From the point of view of public engagement, derbies should therefore be held in areas where lionfish are well established, and where the pool of potential participants is large. However, if the management goal is instead to slow the invasion, early detection is critical. The focus should then shift to areas where no or very few lionfish have been detected, and the derby approach modified to a more frequent or continuous, monitoring-like incentive scheme. 相似文献
45.
《Marine Policy》2016
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
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F. G. ONeill 《Ocean Engineering》2003,30(16):2053-2063
A theoretical investigation is carried out of the mesh size measurement of an idealized fishing netting mesh. It is assumed that the bending moment of the netting twine is proportional to curvature and that there is no twine extension and no cross-sectional deformation of the twine. The corresponding momentum and force balance equations are analyzed. The measurement method our analysis most approximates is that of the ICES gauge. The effect on mesh measurement of twine bending stiffness, frictional resistance, boundary slope, gauge force and gauge thickness are all examined. 相似文献
48.
Investigation of strategies to improve the recycling effectiveness of waste oil from fishing vessels
The marine ecological environment and fishery resources can be severely polluted or destroyed by waste oil from fishing vessels if they are emitted directly into the ocean without any proper pre-treatment process. International conventions such as MARPOL 73/78 regulate waste-oil emissions and require the installation of a waste oil–water separator only for ocean-going ships of over 400 gross tons. Hence, these international conventions are not applicable to most fishing ships due to their low gross tonnages. In addition, space on most fishing vessels is too limited to allow waste-oil storage tanks or a waste oil-water separator to comply with international maritime regulations. Because a significant amount of waste oil is produced by fishing vessels around the world every day, effective strategies or measures are needed to prevent this waste oil from polluting the marine environment. This study thus investigates strategies and measures for improving the effectiveness of waste-oil collection from fishing vessels. This study found that existing procedures for the collection and treatment of waste lubricating oil on land could be applied to the management of waste oil and bilge water from fishing vessels. Sufficient oil–water separators and storage facilities for the collection of waste oil should be placed at each fishing port and shipyard. Fishermen should then be required to deliver their waste oil to these storage facilities, from where it can be transported to legal recycling companies for further treatment. In addition, fishing harbor authorities should bear definitive responsibility for monitoring the illegal dumping of waste oil and for checking the waste-oil record books of fishing vessels. Each maritime country should enforce relevant laws and regulations to reduce the emission of waste oil from fishing vessels into the ocean. 相似文献
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Towards end-to-end models for investigating the effects of climate and fishing in marine ecosystems 总被引:2,自引:0,他引:2
End-to-end models that represent ecosystem components from primary producers to top predators, linked through trophic interactions and affected by the abiotic environment, are expected to provide valuable tools for assessing the effects of climate change and fishing on ecosystem dynamics. Here, we review the main process-based approaches used for marine ecosystem modelling, focusing on the extent of the food web modelled, the forcing factors considered, the trophic processes represented, as well as the potential use and further development of the models. We consider models of a subset of the food web, models which represent the first attempts to couple low and high trophic levels, integrated models of the whole ecosystem, and size spectrum models. Comparisons within and among these groups of models highlight the preferential use of functional groups at low trophic levels and species at higher trophic levels and the different ways in which the models account for abiotic processes. The model comparisons also highlight the importance of choosing an appropriate spatial dimension for representing organism dynamics. Many of the reviewed models could be extended by adding components and by ensuring that the full life cycles of species components are represented, but end-to-end models should provide full coverage of ecosystem components, the integration of physical and biological processes at different scales and two-way interactions between ecosystem components. We suggest that this is best achieved by coupling models, but there are very few existing cases where the coupling supports true two-way interaction. The advantages of coupling models are that the extent of discretization and representation can be targeted to the part of the food web being considered, making their development time- and cost-effective. Processes such as predation can be coupled to allow the propagation of forcing factors effects up and down the food web. However, there needs to be a stronger focus on enabling two-way interaction, carefully selecting the key functional groups and species, reconciling different time and space scales and the methods of converting between energy, nutrients and mass. 相似文献