浙江中南部外侧海区的虾类资源

本文根据1986年8月至1987年11月浙江中南部海域(27°00′～29°30′N,125°00′E) 拖虾调查资料,分析了虾类资源的种类、组成,拖虾渔获量及主要种类的分布,提出进一步开发凹管鞭虾,假长缝拟对虾等新的虾类资源的建议,并讨论了合理利用的途径。     

对虾白斑综合症病毒病围栏封闭预防技术研究简报

病毒性流行病使世界的养虾业遭受到了严重挫折 ,其中又以白斑综合症病毒 (ＷＳＳＶ)病流行最广 ,危害最大。针对这种病的病原、病理和流行病学已进行了大量的研究 ,对于如何预防也做了很多探索 ,但迄今没有得到很好的解决。养虾界总结出高位池塘养殖、内地淡化养殖、远海岸卤水、井水或渗水养殖和虾池配养肉食性鱼类等办法 ,都有一定的效果。但这些办法大多要求一定的条件 ,缺乏普适性 ,而且往往有时效限制 (即养殖年久后也会发病 ) ;有的则只是减小了发病机率 ,并不是十分可靠 (如配养肉食性鱼类 )。因此 ,研制出一种具有普适性 (特别是能…     

对虾养殖生态系不同粒级浮游生物呼吸率和初级生产率测定

1997年6～8月于山东省海阳市黄海集团公司养虾场,用5个实验围隔研究了对虾池不同粒级浮游生物的呼吸率和初级生产率.结果表明:(1)小型、微型及超微型浮游生物的呼吸率平均分别为0.07,0.38及0.31mg/(dm3·d),占各粒级浮游生物总呼吸率的9%,50%及41%.小型、微型及超微型浮游植物的生产率平均分别为0.04,1.26及0.15mg/(dm3·d),占相应粒级浮游植物总生产率的3%,87%及10%.各粒级浮游生物呼吸率占相应粒级浮游植物生产率的比例为:小型浮游生物175%;微型浮游生物30%;超微型浮游生物207%.(2)小型浮游动物、超微型浮游动物(含细菌)的呼吸率显著高于相应粒级浮游植物呼吸率,微型浮游植物的呼吸率明显高于微型浮游动物呼吸率.不同粒级浮游植物呼吸率的大小顺序为微型、超微型、小型,不同粒级浮游动物呼吸率顺序为超微型(含细菌)、微型、小型.     

The economic sustainability of artisanal fisheries: the case of the trawl ban in the Gulf of Castellammare, NW Sicily

Small-scale fisheries and the communities they support are often given the protection of designated fishing zones from which non-artisanal vessels are excluded. This paper looks at one example of this approach, the trawl ban introduced in the Gulf of Castellammare (NW Sicily), focussing on the economic sustainability of the artisanal fishery currently operating within the protected area. The consequences of lifting the trawl ban and how far this would jeopardise the sustainability of the artisanal fishery are explored via an analysis of the financial viability of trammel net vessels under alternative assumptions concerning catch rates. The paper also investigates fishermen's attitudes towards the trawl ban and their predisposition either to remain in the fishery or to quit in the event of the ban being removed.     

Episodic Mass Invasions of Juvenile Gadoids into the Wadden Sea and their Consequences for the Population Dynamics of Brown Shrimp (Crangon crangon)

Abstract. The brown shrimp Crangon crungon is considered to be a key species in the coastal waters of the North Sea and in particular in the Wadden Sea, since it occurs in masses and acts as both a highly efficient predator and important prey. The Wadden Sea is the nursery ground for brown shrimp. In 1990, a mass invasion of O-group whiting ( Merlangius merlangus ) reduced Crangon numbers to almost zero. Similar events, which had previously been reported in the 19th century, were observed in 1959 (whiting), 1970 (cod, Gadus morhua ), and 1983 (cod and whiting).
The 1990 invasion and the decline of the shrimp stock are documented on the basis of surveys that are compared with the years preceding and following. Consequences for the food web in the Wadden Sea and the reasons for the complete recovery of the shrimp stock in each case within one year after its collapse are discussed with regard to the Crangon crungon behaviour and reproductive potential. Sampling error and the impact of fisheries are also considered.