A review of game-theoretic models of fishing

Game theory is a formal tool for analysing strategic interaction between a finite number of agents. The fact that usually more than one entity or agent has property rights to fishery resources, has led to an explosion in the use of game theory and applications thereof to analyse fishery management problems. This review shows that game-theoretic modelling has made significant contributions to our understanding of the problems of fishery resource management. However, many challenges still remain. For instance, models of straddling stocks are yet to be fully developed. In addition, fisheries economists have not yet fully exploited the opportunity provided by computational methods now available, and the ever increasing power of computers, to develop more empirical game-theoretic models for practical fisheries management.     

福建近海五种主要捕捞作业适宜捕捞力量的研究

本文根据福建省定置、拖、围、刺、钓五种捕捞作业在本省近海的捕捞力量和渔获量,并以１９９４年单位功率的渔捞效率为基准进行逐年捕捞力量的标准化,应用Ｓｃｈａｅｆｅｒ和Ｆｏｘ两同电脑分别估算它们的ｆＭＳＹ和ＭＳＹ。结果两处在算的ｆＭＳＹ和ＭＳＹ的平均值是：定置网为８．９０尤明等３７．４１万ｔ;推网为５５．８８万ＫＷ,３５．５１万ｔ;为桃围网为７．１２万ＫＷ,１０．０６万ｔ;刺网为１５．１９万ＫＷ,９．５     

基于海洋要素时空配置的渔场形成机制发现模型和应用

针对海洋时空要素和相关渔业资源的互动性及非线性关系,分析了带空间结构的变量间关系问题,建立基于海洋要素场时空配置的渔场形成机制发现模型.将海洋要素场的空间配置用邻域进行表达,并将邻域所取得的要素状态变量转换为决策系统的关系表,以提取海洋场时空配置和渔场形成的时空关联规则.以大沙渔场形成的温度场时空配置发现为实例,验证模型的可行性.     

Alaskan fishing community revenues and the stabilizing role of fishing portfolios

Fishing communities are subject to economic risk as the commercial fisheries they rely on are intrinsically volatile. The degree to which a community is exposed to economic risk depends on a community׳s ability to confront and/or alter its exposure to volatile fishery conditions through risk-reduction mechanisms. In this article, economic risk – as measured by community-level fishing gross revenues variability – is characterized across Alaskan fishing communities over the past two decades, and exploratory analyses are conducted to identify associations between community attributes and revenues variability. Results show that communities’ fishing portfolio size and diversification are strongly related to fishing revenues variability. Communities with larger and/or more diverse fishing portfolios experience lower fishing revenues variability. Portfolio size and diversification appear to be related to the number of local fisheries, indicating that communities’ portfolios may be constrained to the set of local fisheries. Hotspots of relatively higher fishing revenues variability for communities in north and west Alaska were identified, mirroring the spatial distribution of fishery-specific ex-vessel revenues variability. This overall pattern suggests that a community׳s fishing portfolio – and hence its exposure to risk – may be “predetermined” by its location, thereby limiting the policy options available to promote economic stability through larger and/or more diverse fishing portfolios. For such communities, diversifying income across non-fishing sectors may be an important risk reduction strategy, provided any potential negative cross-sector externalities are addressed.     

诱鱼灯光场计算及其对光诱鱿鱼浮拖网作业的影响

本文运用诱鱼灯光照度的有关公式,计算了光诱鱿鱼浮拖网作业中的光场分布及变化,结合鱿鱼趋光行为习性,分析现有渔具渔法的适应性。结果表明;使用１６盏铊铟灯水上灯,诱鱼最大水平距离比仅使用水下灯增加约６８０倍,但水上灯从１６盏增加到４０盏地,从经济角度分析不很理想;在集鱼过程中,关闭最后一组水上灯后,应有白炽灯经过降压后再地渡到水下灯集鱼;导鱼灯在向网口移动的过程中应继续降低低电压;     

A critical review of fishing agreements with tropical developing countries

Many African, Caribbean and Pacific (ACP) countries sell fishing licenses to distant water fleets. Fishing agreements have the potential to improve the performance of local fishing sectors. They create income that can be reinvested into domestic industries and often go along with partnerships in management and enforcement. However, many fishing agreements run a serious risk of undermining sustainable resource management. The present study critically reviews trends in distant water fishing as well as identifies those tropical host countries most dependent on fishing agreements. It is shown that traditional, more responsible distant water fleets (DWFs) are being displaced by less responsible, low-cost DWFs and that the most vulnerable host countries are small coastal states with large exclusive economic zones that lack the ability to benefit from value adding processes associated with fishing. The results suggest that the once-promising concept of fishing agreements is gradually posing a threat to both economic development and environmental sustainability of ACP countries.     

A new model to extract environmental pattern for fishing ground

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Artisanal fishing in Andalusia: A statistical study of the fleet

Andalusia is a region of Spain with an area of some 90,000 km² and almost 900 km length of coastline. It has an important tradition in the fishing industry that makes it one of the areas of the European Union where fisheries policies have a great significance for the population. The present statistical study deals comprehensively with the so-called “artisanal fleet”, especially in respect of data on the typology of vessels (construction particulars) and on the extractive effort made (distances and depths where they fish, duration of fishing voyages, the fishing gear used and target species), with the aim of presenting a new approach in the policies for regulating this important fisheries sector.     

Do fishing vessel buyback programs work: A survey of the evidence

Vessel and license buyback programs are being used increasingly as a tool to reduce overcapacity in fisheries. This paper examines buybacks programs in a number fisheries around the world, in order to evaluate their effectiveness in achieving their objectives. We show that, though the objectives are usually similar, the design of different buyback programs varies widely with important ramifications. Although proper design can improve the performance of buyback programs, we conclude that buyback programs are generally not an effective way to address the problems they are meant to solve.     

Can cod farming affect cod fishing? A system evaluation of sustainability

The cod resources in the Barents Sea constitute the most important fisheries in Norway. In order to reduce resource allocation conflicts among different gear and vessel groups and to ensure profit for all participants throughout the value chain, the sector is thoroughly organized. The institutions established to ensure long-term sustainability, have been developed within the framework of a joint Norwegian–Russian fisheries management regime. However, due to a very high fishing mortality, the cod stock is now under severe pressure. In addition, a major part of the cod fisheries is highly seasonal and unable to be a stable supplier to neither the land-based industry nor demanding international markets. In parallel, cod farming is expected to become a new emerging industry, with potential to copy the success of farmed Atlantic salmon. Many actors within the cod fisheries fear the future competition from the growing cod farming sector. With reference to important attributes that characterize the cod fisheries and cod farming, this paper discusses how a future farming industry may affect the traditional cod fisheries. Moreover, we discuss how the fisheries may be forced to organize in the future to encounter the expected competition from cod farming.     

A dynamic two-dimensional calculation of underwater lines

On the basis of a lumped mass method in two-dimension, we derive a dynamic calculation method for a system including both extensible and inextensible underwater lines. The Newmark beta method is used in numerical integration with respect to time. The Newton Raphson method is applied so that the numbers of iterations are reduced. A transient response of a line during deployment is calculated.     

The Canary Islands fishing policy

In the last 20 years the Canary Islands fishing fleet has gone from the privileged position of enjoying abundant catches in the old “Canary Islands-Saharan” fishing grounds to the precarious situation in which it currently finds itself. This paper aims to determine what the future holds for The Canaries fishing sector. Hence, fishing rights and policies are analysed and the special aids received from the EC are compared with those applied in other similar ultraperipheric regions. The adoption of a more interventionist role by the Canary Islands administration may solve at least part of the problem faced by this sector.