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71.
利用数据挖掘方法对1990年1月—2001年7月10余年的WCPO金枪鱼围网作业生产数据以及该时段的18个与WCPO金枪鱼围网产量相关的海洋环境因子进行分析,将信息增益分析技术和基于粗糙集的属性化简方法相结合用以确定影响WCPO金枪鱼围网产量的关键因子集。利用多元回归分析方法建立基于关键因子集的预测模型,经过大量试验对比选择较佳的预测模型,达到了理想的效果。同时,验证了所确定关键因子集的可靠性,有效性。首次利用多种数据挖掘方法相结合的方式对多种影响因子进行分析,开展渔情预报研究,达到了较好的效果,为渔情预报研究提供了一种新思路,同时为渔业生产提供了可靠的依据。 相似文献
72.
Since the 1960s Taiwan has been a significant player in the global distant water tuna fisheries (DWTF). However, Taiwan's lack of political recognition has led some fisheries businesses to employ less conventional methods including Flags of Convenience (FOCs) in harvesting tuna resources. Meanwhile, Taiwan has been experiencing the painful cost of readjusted DWTF policies. This paper compares the readjusted policies in accordance with international management instruments and tuna compliance requirements (Compliance Agreement and UNFSA) and domestic laws are already undergoing adjustments to take these into account. This again demonstrates Taiwan's unique position in the international community: despite it not being a member of the United Nations, Taiwan spares no effort to ensure the sustainability of marine resources, and does its utmost to fulfill the responsibilities and duties of a Flag State. 相似文献
73.
74.
Balshaw S Edwards JW Ross KE Ellis D Padula DJ Daughtry BJ 《Marine pollution bulletin》2008,56(12):2009-2017
Two empirical models are presented to elucidate the mechanisms driving reductions in the mercury concentration of southern bluefin tuna (SBT) during culture. Model 1 predicts temporal fluctuations in mercury concentration in response to growth dilution. Model 2 predicts the combined effects of growth dilution and linear mercury accumulation. Model 2 was found to be the more accurate model. Over a typical farming period of 136 days, growth dilution resulted in a reduction in mean mercury concentration of SBT edible tissues from 0.51 mg/kg down to 0.33 mg/kg. Extended culture beyond 136 days resulted in an increase in mercury concentration due to the combined effects of mercury accumulation and seasonal lipid depletion. Results indicate that under current industry practice, cultured SBT can be consumed twice as frequently as that of wild caught SBT while maintaining total dietary mercury intake below national recommendations. 相似文献
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77.
We investigate the interactions between anthropogenic climate change, socioeconomic developments and tuna fishery management strategies. For this purpose, we use the APECOSM-E model to map the effects of climate change and commercial fishing on the distribution of skipjack tuna biomass in the three oceans, combined with a new bioeconomic module representing the rent or profit of skipjack fisheries. For forcing, we use Representative Concentration Pathway (RCP) 8.5, the highest emission scenario for greenhouse gas concentrations presented in the IPCC’s Fifth Assessment Report (AR5), and the IPCC Socioeconomic Shared Pathway (SSP) 3, which is characterized by low economic development and a strong increase in the world population. We first investigate the impact of climate change on regional skipjack abundance, catches and profits in three oceans (Atlantic, Indian and Pacific) in 2010, 2050 and 2095. We then study the effects of three management strategies (maximum sustainable yield or MSY, maximum economic yield or MEY, and zero rent or ZR) on the future distribution of fishing fleets between oceans and on global economic rent.Our model projections for 2050 and 2095 show an increase in global skipjack biomass compared to 2010 and major changes in its distribution, impacting local and regional fishing efforts. The Pacific Ocean will continue to dominate the skipjack market.In our modeling of management strategies, the currently predominant MSY strategy would have been unprofitable in 2010, due to a decreased catch per unit effort (CPUE). In the future, however, technological developments should increase fishing efficiency and make MSY profitable.In all the scenarios, a MEY strategy is more profitable than MSY but leads to the lowest catches and the highest prices. This raises ethical questions in a world where food security may become a top priority.In the scenarios where MSY generates an economic loss (e.g. 2010), a ZR strategy allows global stocks to be exploited at high but still profitable levels. Conversely, in the scenarios where MSY is profitable, (e.g. 2095) ZR leads to overfishing and smaller global catches.We conclude that the most appropriate management strategy at any time is likely to change as environmental and socioeconomic conditions evolve. The decision to follow one or other strategy is a complex one that must be regularly reviewed and updated. 相似文献
78.
Jason R. Hartog Alistair J. HobdayRichard Matear Ming Feng 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):746-752
Southern bluefin tuna (SBT) are presently a quota-managed species in the multi-species eastern Australian tuna and billfish longline fishery (ETBF). Capture of SBT is regulated by quota, as is access to regions likely to contain SBT. A habitat prediction model combining data from an ocean model and pop-up satellite archival tags is used to define habitat zones based on the probability of SBT occurrence. These habitat zones are used by fishery managers to restrict access by ETBF fishers to SBT habitat during a May-November management season. The zones display a distinct seasonal cycle driven by the seasonal southward expansion and northward contraction of the East Australia Current (EAC) and as a result access by fishers to particular ocean regions changes seasonally. This species also overlaps with the commercially valuable yellowfin tuna (YFT), thus, we modified the SBT model to generate YFT habitat predictions in order to investigate habitat overlap between SBT and YFT. There is seasonal variation in the overlap of the core habitat between these two species, with overlap early (May-Jul) in the management season and habitat separation occurring towards the end (Aug-Nov). The EAC is one of the fastest warming ocean regions in the southern hemisphere. To consider the future change in distribution of these two species compared to the present and to explore the potential impact on fishers and managers of the future, we use future ocean predictions from the CSIRO Bluelink ocean model for the year 2064 to generate habitat predictions. As the ocean warms on the east coast of Australia and the EAC extends southward, our model predicts the suitable habitat for SBT and YFT will move further south. There was an increase in the overlap of SBT and YFT habitat throughout the management season, due to regional variation of each species’ habitat. These results illustrate that a management tradeoff exists between restricting fisher access to SBT habitat and allowing access to YFT habitat. We suggest that some options to address this tradeoff are possible by identifying the seasonal variability of the overlap. 相似文献
