共查询到20条相似文献,搜索用时 15 毫秒
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Fogarty Michael J.; Myers Ransom A.; Bowen Keith G. 《ICES Journal of Marine Science》2001,58(5):952-961
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The decline of the herring stocks and the gadoid outburst 总被引:2,自引:1,他引:2
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Long-term changes in zooplankton and the climate of the North Atlantic 总被引:13,自引:3,他引:10
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When the Regional Advisory Councils (RACs) were created during the last reform of the Common Fisheries Policy (CFP) in 2002, it was recognised that in addition to the five geographically orientated stakeholder lead advisory bodies, a separate RAC dedicated exclusively to pelagic fisheries was needed because of it being so distinctly different from other fisheries. Pelagic fishing is different mostly due to the fact that the targeted fish species behave in a unique manner by grouping in schools in mid-water unlike other commercially targeted fishes, which typically reside on or near the ocean floor. For this reason, as well as the fact that they are usually widely distributed, researching and managing this dynamic group of fishes across the borders of many countries requires a unique approach. Fortunately, despite these complexities, policy makers have succeeded to establish a reasonably well functioning management framework, which has lead to the situation that most pelagic fish stocks are harvested biologically sustainable. While a majority of Europe's fish stocks still need rebuilding, and the main aim accordingly is to reduce fishing mortality, the current focus for pelagic fish stocks is to improve the performance of already implemented Long Term Management plans in terms of their biological as well as social and economical objectives. This paper reflects upon experiences of the Pelagic Regional Advisory Council (PRAC) in its role as advisor to the EU institutions. Subsequently, in the context of ideas presented in the European Commission's Green paper, the authors discuss the future of the PRAC and conclude that its main development potential lies not with the current EU's CFP reform, but rather should be sought in a wider international context. 相似文献
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Friedland Kevin D.; Chaput Gerald; MacLean Julian C. 《ICES Journal of Marine Science》2005,62(7):1338-1349
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《Marine Policy》2016
This study examines the status and exploitation level of 31 northern European stocks targeted by fisheries certified by the Marine Stewardship Council (MSC) as being sustainable and well managed. In the first year of certification, 11 stocks (52% of stocks with available data) were exploited above the maximum sustainable level and four stocks (16% of stocks with available data) were outside of safe biological limits. MSC states that it certifies sub-standard stocks because they will improve once they are in their program. However, after a duration of certification of one to ten years (average four years), no significant changes in fishing pressure or stock size were detected. In the last certified year with available data, seven stocks (44% of stocks with available data) were subject to overfishing and five stocks (21% of stocks with available data) were outside of safe biological limits. Certification should guarantee that fishing quotas are set correctly and are enforced. However, in 11 stocks quotas were set 20–60% above the level that fishers were taking, whereas in three stocks landings exceeded quotas by 30–50%. The study concludes that MSC should change its rules such that overfishing or unsafe stock sizes lead to immediate suspension of certification and that no certification is issued in the first place for a stock that is already in such a situation. 相似文献
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J. A. Dalziel 《Marine Chemistry》1995,49(4)
The vertical distribution of reactive mercury has been measured at two stations in the eastern North Atlantic and one station in the southeast Atlantic in conjunction with the IOC Open Ocean Baseline Survey. The average concentrations of reactive Hg in vertical profiles ranged from 0.70 to 1.07 pM with the highest values found at the northeast Atlantic stations and the lowest at the southeast station. No significant concentration gradients were found below the surface mixed layer at the two stations in the eastern North Atlantic. At station 7, in the southeast Atlantic, an increase in reactive Hg was noted in the water adjacent to the mixed layer (35–200 m) which was coincident with an oxygen depletion, down to 20% saturation at 200 m. The concentration of reactive Hg in the North Atlantic Deep Water (0.48–1.34 pM), the Antarctic Intermediate Water (0.47 pM), the Antarctic Bottom Water (0.67–1.25 pM), and the Mediterranean Outflow Water (0.83–1.06 pM) were noted. The trends in Hg concentration in the water masses between stations showed the concentration decreasing with distance from the water mass source except for Hg in the Antarctic Bottom Water. The increase noted in this water mass was attributed to mixing with North Atlantic Deep Water and or release from bottom sediments. 相似文献
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Recent changes in the North Atlantic circulation simulated with eddy-permitting and eddy-resolving ocean models 总被引:1,自引:0,他引:1
Robert Marsh Beverly A. de Cuevas Andrew C. Coward Julien Jacquin Joel J.-M. Hirschi Yevgeny Aksenov A.J. George Nurser Simon A. Josey 《Ocean Modelling》2009,28(4):226-239
Three eddy-permitting (1/4°) versions and one eddy-resolving (1/12°) version of the OCCAM ocean model are used to simulate the World Ocean circulation since 1985. The first eddy-permitting simulation has been used extensively in previous studies, and provides a point of reference. A second, improved, eddy-permitting simulation is forced in the same manner as the eddy-resolving simulation, with a dataset based on a blend of NCEP re-analysis and satellite data. The third eddy-permitting simulation is forced with a different dataset, based on the ERA-40 re-analysis data. Inter-comparison of these simulations in the North Atlantic clarifies the relative importance of resolution and choice of forcing dataset, for simulating the mean state and recent variability of the basin-scale circulation in that region. Differences between the first and second eddy-permitting simulations additionally reveal an erroneous influence of sea ice on surface salinity, dense water formation, and the meridional overturning circulation. Simulations are further evaluated in terms of long-term mean ocean heat transport at selected latitudes (for which hydrographic estimates are available) and sea surface temperature errors (relative to observations). By these criteria, closest agreement with observations is obtained for the eddy-resolving simulation. In this simulation, there is also a weak decadal variation in mid-latitudes, with heat transport strongest, by around 0.2 PW, in the mid-1990s. In two of the eddy-permitting simulations, by contrast, heat transport weakens through the study period, by up to 0.4 PW in mid-latitudes. The most notable changes of heat transport in all simulations are linked to a weakening of the subpolar gyre, rather than changes in the meridional overturning circulation. It is concluded that recent changes in the structure of mid-latitude heat transport in the North Atlantic are more accurately represented if eddies are explicitly resolved. 相似文献
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