河西内陆河流域生态问题及其保护对策

概述了近代河西内陆河流域生态研究成果、流域构成特点和河西地区环境状况,分析了河西内陆河流域存在的生态问题,并从节水农业和水权制度改革、城镇化建设、植被保护、生态用水管理、环境污染的治理等5个方面提出了生态保护对策。     

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.     

我国渔业政策与渔业管理问题探讨

70年代以来 ,我国黄渤海和东海海域的主要鱼业资源 (ｆｉｓｈｅｒｙｒｅｓｏｕｒｃｅｓ)长期处于衰退状况 ,我国政府意识到海洋资源衰退的时间并不算太晚 ,为此制定和实施了一系列的保持渔业资源的文件和管理法规。建国以来 ,与渔业管理相关的法律、法规性规范性文件达 50 0多件[1] 。表 1　渔船总吨位前 5位的国家 (1 995年 )Ｔａｂ .1　Ｄｅｃｋｅｄｆｉｓｈｉｎｇｖｅｓｓｅｌｓ:ｔｏｐｆｉｖｅｃｏｕｎｔｒｉｅｓｂｙｇｒｏｓｓｔｏｎｎａｇｅ(1 995 )国　　家渔船 (百万吨 )中国 5 .5 5俄罗斯 2 .99日本 1.5 1美国 1.40印度 1.0 8　　…     

对渔业企业在长短期中盈亏状况和生产规模的分析

利润最大化是市场经济条件下,渔业企业追求的目标,那么,渔业企业在什么条件下才能获得最大利润以及在长短期中,随着市场价格的变化,渔业企业的盈亏状况怎样和如何调整生产规模,才能获得最大利润。本文就这些问题进行了分析。     

When aquaculture restores and replaces an overfished stock:Is the conservation of the Species assured? The case of the scallop Argopecten purpuratus in Northern Chile

The fishery for Argopecten purpuratus in northern Chile, whichcollapsed because of overfishing, has been replaced by aquaculture of thespecies. In 1998, cultures produced 16,474 t, while the highest landings recorded inthe entire history of the fishery was in 1984 (one year after the 1983 ElNiño) with 5275 t. The figures for stock size of the species in the pastand at present, show that the wild stock of scallops today represents notmore than 10–15% of the total stock of the species within Chile, with mostof the individuals being kept in sea farms. Thus it is concluded that thescallop already represents a domestic species and, considering theoccurrence and development of selection practices in sea farms,biodiversity within the species appears to be at risk. With the developmentof culture practices over its entire range, there is little use in trying torecover a wild fishery for this scallop. It is urgent, however, that selectednatural beds be protected in order to preserve genetic diversity.     

东海区帆式张网渔业资源利用结构的动态分析

以１９９７、１９９８年“苏海研１、２号”帆式张网资源监测调查船４０２０网次的调查结果及１１４次渔获随机取样的分析结果为依据，对东海区帆式张网渔业资源利用结构的动态进行分析研究，结果表明，东海区帆式张网渔业资源结构春季以小黄鱼、银鲳、黄鲫，夏季以小黄鱼、带鱼、黄鲫，秋季以小黄鱼，带鱼、银鲳、冬季以小黄鱼、带钱赤主要利用对象；主要经济鱼类小黄鱼，带鱼，银鲳的幼鱼渔获得比例以夏季最高为７６．０６％，其余     

Effects of Sowing Methods on Upland Rice in Lowland Rice-Vegetable Sequence in Inland Valley

Triple cropping in the inland valleys of southwestern Nigeria is technically possible but the third crop between the main crop and vegetables has poor establishment due to soil saturation. Identification of appropriate sowing methods is required in this niche. A field experiment was conducted at the University of Agriculture, Abeokuta, Nigeria in 2007/2008 and 2008/2009 cropping seasons to evaluate the effect of sowing methods on the performance of upland rice （Oryza spp.） in a lowland rice-vegetable sequence. The first, second, and third crops in the sequence were planted in May, September and December, respectively. Two upland rice varieties, namely New Rice for Africa 1 （NERICA 1） and ITA 150 constituted the main plot treatments while the subplot treatments were sowing methods. The mean grain yield of lowland rice for two years was 7.74 t ha^-1. The fluted pumpkin had a fresh leaf weight of 14.78 t ha^-1. The grain yields of the two upland rice varieties （1.81 and 1.85 t ha^-1） and sowing methods which ranged between 1.63 and 2.05 t ha^-1 were similar in both cropping seasons. However, the interaction of variety by sowing methods had a significant effect on grain yield. Transplanting and pre-germinated broadcast had the highest grain yield for NERICA 1 while dry broad cast and pre-germinated dibbled had the highest in ITA 150. Hence, the productivity of triple cropping in the inland valley was enhanced by sowing methods.     

Identification and evaluation of shark bycatch in Georgia’s commercial shrimp trawl fishery with implications for management

Abstract Many US states have recreational and commercial fisheries that occur in nursery areas occupied by subadult sharks and can potentially affect their survival. Georgia is one of few US states without a directed commercial shark fishery, but the state has a large, nearshore penaeid shrimp trawl fishery in which small sharks occur as bycatch. During our 1995–1998 investigation of bycatch in fishery‐dependent sampling events, 34% of 127 trawls contained sharks. This bycatch totalled 217 individuals from six species, with Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), the most common and finetooth shark, Carcharhinus isodon (Müller & Henle) and spinner shark, Carcharhinus brevipinna (Müller & Henle), the least common. The highest catch rates for sharks occurred during June and July and coincided with the peak months of the pupping season for many species. Trawl tow speed and tow time did not significantly influence catch rates for shark species. Gear configurations [net type, turtle excluder device (TED), bycatch reduction device] affected catch rates for shark species. Results of this study indicate gear restrictions, a delayed season opening, or reduced bar spacing on TEDs may reduce shark bycatch in this fishery.     

An ecosystem-based assessment of the Korean blue crab trammel net fishery in the Yellow Sea and management implications

Landings in the blue crab, Portunus trituberculatus, fishery in Korean waters of the Yellow Sea have declined substantially from 11,000 t in the 1980s to 2,300 t in 2004. Blue crab habitat quality in the Yellow Sea has been degraded by anthropogenic activities including sand mining, land reclamation, and coastal pollution. Various traditional management measures have been implemented, including closed seasons during spawning and size limits, but these measures alone have been unsuccessful to conserve blue crab stocks. Consequently, a total allowable catch and a stock-rebuilding program using an ecosystem-based management approach were implemented in 2003 and 2006, respectively to rebuild blue crab stocks and restore habitats. This program involved assessment of both blue crab stock status and trammel-net fishery impacts at an ecosystem-level using an ecosystem-based fisheries assessment method ( [Zhang et al., 2009] and [Zhang et al., 2010]), which considered fishery data from catch and effort time-series, crab population biology, and ecosystem characteristics, including habitats and environmental conditions. Recent (2008) management status indices have shown significant positive change compared to conditions in 2000 with respect to sustainability of the stock and fishery and with regards to biodiversity and ecosystem habitat quality.