The conservation and fishery benefits of protecting large pike (Esox lucius L.) by harvest regulations in recreational fishing

Traditional fisheries management theory supports aggressive exploitation of old and large fish to maximize a stock’s biomass production and yield. Here we present an age-structured fish population model with multidimensional density-dependence to test the hypotheses that protection of large, fecund individuals is beneficial for the population and selected fisheries variables and that effects of maternal size on early survival rate change the resilience and fisheries productivity of a pike population (Esox lucius L.) exploited by recreational angling. We find that, compared to the traditional regulatory approach of management by small minimum-length limits (so that culling of large fish is encouraged), preservation of large and old individuals through harvestable-slot length limits promises considerable benefits for fisheries quality, without compromising the long-term conservation of the population. We also find that ignoring maternal effects on early survival of offspring might overestimate the equilibrium spawning stock abundance by up to 17% and the predicted harvest by up to 11%, potentially putting pike populations at risk from overharvest if size-dependent maternal effects are ignored in fisheries models. If the findings from our simulation study hold for empirical systems, they suggest altered harvest regulations in many of consumptive pike recreational fisheries are needed to protect large individuals to a greater extent that currently pursued.     

合村并点新型农村社区建设中的利益博弈

在城乡统筹视角下分析了合村并点新型农村社区建设的必要性,对社会各界存在的异议进行了反思,在此基础上研究了合村并点新型农村社区建设对广大农民生产、生活方面的影响,并提出了相应的对策。     

Long-term trends in the competitive shore fishery along the KwaZulu-Natal coast,South Africa

Twenty-four years (1977–2000) of competitive shore angling catch and effort data from the KwaZulu-Natal Coastal Anglers Union for the province of KwaZulu-Natal were analysed. Of a minimum of 117 species recorded, the most commonly caught species were dusky shark (Carcharhinus obscurus) (26%), milk shark (Rhizoprionodon acutus) (18%) and shad (Pomatomus saltatrix) (10%). By weight, the top species were dusky shark (34%) and diamond ray (Gymnura natalensis) (19%). All the above species showed considerable inter-annual variation in their respective contributions to annual catch. Probably as a result of changes in fishing patterns, dusky shark and milk shark showed a general decline in percentage contribution to catch over the period, while contributions of lesser guitarfish (Rhinobatos annulatus), giant guitarfish (Rhynchobatus djiddensis), diamond ray (Gymnura natalensis) and brown ray (Himantura gerrardi) increased. Mean overall annual cpue by number and weight showed a non-significant increase over the period, while each of the investigated species showed a constant trend in mean annual weight. There were high proportions of juveniles in the catches of dusky shark (100%), dusky kob (92%) and giant guitarfish (78%). Improvements made to the structure of shore angling competitions and the overall contribution of competition angling to resource management in South Africa is discussed.     

北太平洋(160°E～170°E)大型柔鱼渔场的初步研究

本文根据1997年6月～7月北太平洋（16°E～170°E）海域柔鱼探捕调查的资料，对渔场形成的海洋环境条件进行了初步分析。160°E～170°E海域的大型柔鱼渔场主要由亲潮策3和第4分支与黑潮的第4和第5分支交汇形成，特别是在深层（100米水层）的暖水域前端形成。其表层水温一般为11～13°，100米水层水温约为9～10℃。其中167°E～170°E海域的渔场较为稳定，可供北太平洋鱿钓船的前期生产。中心渔场形成时常有浮游生物层。浮游生物层越厚实，渔获量越高，但有关浮游生物层的形成原因需作进一步的研究与探讨。     

博弈论在国际市场竞争中的作用

针对当前我国企业参与国际竞争的实际背景，研究国际市场的进入与退处次运用静态博弈与动态博弈的原理和方法。讨论了企业对于未进入的市场是否可以进入，以及怎样才能进入的问题，同时讨论了如何保住已经占领的市场和进一步扩大已占领的市场份额，击退竞争对手，获得了最大市场利润的问题。     

生态文明建设下退耕还湿必要性与成效分析——基于博弈和模糊评价视角

退耕还湿既是生态文明建设的要求,又是人们对美好环境向往的时代需求。以退耕还湿的必要性和成效为研究基点,通过主体利益博弈和模糊综合评判来阐明该工程的推行选择和效益发展。政府和农户利益博弈的结果是双方反复博弈后最终会以群体高比例达成最优均衡战略[服从,补偿],从主体层面表明退耕还湿具有必要性;运用AHP-Fuzzy模型对20个具有代表性的湿地因子从经济、社会、生态3方面效益对三江平原湿地进行综合评价,得出各效益最大隶属度分别是3、4、3,综合效益最大隶属度为3,处于潜力发展期,表明退耕还湿的实施有成效,具有较好的发展前景。最后,针对两种方法和结果,给出了相应结论及相关建议。     

有关捕捞能力量化统计方法的探讨

文章介绍了在我国渔业统计资源中，与捕捞能力相关的项目，以及在渔业管理初中中，对捕捞能力进行宏观控制的主要指标：渔船数、主机总功率和总吨位等，还介绍了我国近海渔业中单一和复合渔业捕捞能力的量化方法，并对各种作业方式中影响捕捞能力的主要因素进行了分析，提出在量化计算时应注意的问题。本文以东、黄海底托网渔业为进行捕捞能力的修正。由于影响捕捞能力的因素很多，文章还初步得出利用灰色系统理论建立捕捞能力的综合指数的设想和可行性，以便较为全面地反映和统一量化不同渔船或多种渔业的捕捞能力，供渔业管理参考。     

金融生态主体博弈行为理论研究与政策建议

通过对金融生态主体：政府、金融缉织、非及金融组织的行为倾向进行分析，在心里学与利益制衡范畴解释其行为动机，和这一动态演进过程造成的结果。然后，模拟金融生态主体博弈过程，借助其在社会范围之内的相互联系、相互影响、共同作用，反过来影响和形成了短期社会规则，并影响金融生态的长期构建。     

我国独立审计质量的经济学分析

我国独立审计市场存在的种种问题表明 ,我国审计市场环境较差、审计质量较低。其原因在于独立审计市场上存在的审计供给和需求的深层次矛盾。本文从信息经济学角度分析我国独立审计市场上的供需双方的博弈关系后 ,认为只有处理好供需双方的矛盾 ,才能较好地解决问题     

渔船碰撞事故责任分析中应注意的若干问题

随着海洋渔业的发展,渔船数量不断增多,船舶间碰撞事故的发生也就难以避免了。渔港监督部门作为主管机关在受理碰撞事故后,必然要进行责任分析,明确双方当事船舶的责任分摊。本文依据《1972年国际海上避碰规则》,提出了渔船碰撞事故责任分析中应注意的若干问题,以便有关部门参考。