闽中地区单拖作业捕捞能力的因子分析

单拖作业是福建省闽中地区重要的作业渔具之一。在捕捞生产过程中渔具受到诸多因素的影响,各种因素对渔具捕捞能力的影响程度不同,给捕捞力量的量化计算和管理带来困难。为了了解各因子对单拖作业捕捞能力发挥的影响程度,本文选择影响单拖捕捞能力发挥的12个因子指标,采用因子分析法对其进行分析。结果表明,可将影响单拖捕捞能力发挥的诸多因素归并为网具结构、渔船作业能力、船龄、渔民捕捞技能4个公共因子,它们在单拖捕捞过程中所做的贡献率依次为网具结构52.87%,渔船作业能力24.46%,船龄7.05%,捕捞技能4.73%。本文还计算和讨论了各样品船的因子得分,通过各因子的得分和综合得分,可对各样品船的捕捞能力发挥情况进行综合评价,为渔业生产和管理提供参考。     

Daily ration of Japanese Spanish mackerel Scomberomorus niphonius larvae

SUMMARY: Diel successive samplings of Japanese Spanish mackerel Scomberomorus niphonius larvae were conducted throughout 24 h both in the sea and in captivity in order to estimate their daily ration. Using the Elliott and Persson model, the instantaneous gastric evacuation rate was estimated from the depletion of stomach contents (% dry bodyweight) with time during the night for wild fish (3.0–11.5 mm standard length) and from starvation experiments for reared fish (8, 10, and 15 days after hatching (DAH)). Japanese Spanish mackerel is a daylight feeder and exhibited piscivorous habits from first feeding both in the sea and in captivity. Feeding activity peaked at dusk. The estimated daily ration for wild larvae were 111.1 and 127.2% in 1996 and 1997, respectively; and those for reared larvae ranged from 90.6 to 111.7% of dry bodyweight. Based on the estimated value of daily rations for reared fish, the total number of newly hatched red sea bream Pagrus major larvae preyed by a Japanese Spanish mackerel from first feeding (5 DAH) to beginning of juvenile stage (20 DAH) in captivity was calculated to be 1139–1404.     

Integrating remote sensing in fisheries control

Abstract  To complement existing fishery control measures, in particular the Vessel Monitoring System (VMS), a pilot operational system to find fishing vessels in satellite images was set up. Radar is the mainstay of the system, which furthermore includes fully automated image processing and communication protocols with the authorities. Different image types are used to match different fisheries – oceanic, shelf and coastal. Vessel detection rates were 75–100% depending on image type and vessel size. Output of the system, in the form of an overview of vessel positions in the area highlighting any discrepancies with otherwise reported positions, can be at the authorities within 30 min of the satellite image being taken – fast enough to task airborne inspection for follow up.     

木麻黄树干细胞组织结构与对星天牛抗虫性的关系

本文报道了４个品系木麻黄木材组织显微解剖结果，分析了木材导管、导管间区木化细胞和射线等物理特征，探讨了木麻黄抗虫机制。高抗品系Ｃ４４木材导管数量少，单位面积（１ｍｍ２）仅有２０．２５个导管，且占木材面积少，仅为９．７２％；导管间区木化细胞较明显，壁厚与腔径比值最大，为５６．５９；单位面积射线的束数、长度、宽度和射线面积／总面积等指标均为最低。说明该品系木麻黄木质部水分含量低、材质坚硬致密、木质部提供养分少，因而不利于星天牛幼虫的生存发育。     

藤茎的导管分子研究

本文描述了棕榈科省藤属及黄藤属共24种藤茎的导管分子。毛鳞省藤(Calamus thysanolepis Hance)仅具单穿孔板,其余藤种均有单穿孔板和复穿孔板,但具复穿孔板导管分子的数量少,并且大部分存在于维管区外围。此外,观察到少数具复穿孔板的螺纹导管分子。自茎的外围向内,后生木质部导管分子的宽度增大;多数藤种的导管分子长度呈增大的趋势,部分藤种则相反,或无规律。     

Estimating understory vegetation response to multi-nutrient fertilization in Douglas-fir and ponderosa pine stands

Models were developed to predict understory vegetation response to multi-nutrient fertilization at six conifer-forested stands in the inland Northwest United States. Equations are presented to estimate how fertilization as well as other factors impacting understory production in the inland Northwest change total understory vegetation production and the production of three individual lifeforms (shrubs, forbs, and grasses and grass-likes). Overstory stand density was found to have the greatest impact on understory production, and regardless of factors such as fertilization or precipitation, large stand densities will limit understory production. At lower stand densities, multi-nutrient fertilization as well as greater amounts of precipitation will increase understory production. These factors were also found to be synergistic; thus, greater amounts of precipitation increase the effects of multi-nutrient fertilization on understory production. For sites of the same stand density, Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] was shown to have a greater negative impact on understory production than ponderosa pine (Pinus ponderosa Dougl. ex Laws.). The models predict that multi-nutrient fertilization of ponderosa pine stands will produce increases in understory production across a broader range of stand densities.     

柚木次生木质部导管分子观察研究

运用细胞图象分析系统及显微照相的方法对柚木次生木质部导管分子进行了观察研究.在柚木的次生木质部导管分子中存在着许多不同的样式,分别对其进行了描述,并从导管分子个体发育与系统发育的角度进行了讨论.     

Mass mortality of common eiders (Somateria mollissima) in the Dutch Wadden Sea, winter 1999/2000: starvation in a commercially exploited wetland of international importance

Mass mortality of common eiders (Somateria mollissima) was observed in winter 1999/2000 in the Dutch Wadden Sea. Approximately 21,000 common eiders died. Dissected birds were severely emaciated and 94% were infected with the acanthocephalan parasite Profilicollis botulus. Green shore crabs (Carcinus maenas), intermediate hosts of the parasite, were slightly more ‘available’ than in other years, but parasite infections in the eiders were close to normal. Few eiders were oiled (5%), there were no toxicological, bacteriological, or virological explanations for the observed mortality.In the Wadden Sea, a wetland of international importance, mussel (Mytilus edulis) cultures occur in sublittoral areas, while mechanical cockle (Cerastoderma edule) fisheries are licensed annually after evaluation of available resources. The wintering eiders in 1999/2000 required c. 3.1 million kg ash-free dry mass, while information on mussel and cockle stocks (irrespective of accessibility and profitability) suggested a resource 4.7× the requirement of common eiders only. Food shortage is suggested to have caused the observed mortality, involving both principal (mussels and cockles) and secondary (Spisula) prey.Winter census reports showed shifts in wintering distribution of common eiders in the 1990s, indicating the utilisation of Spisula in the North Sea in poor food years in the Wadden Sea. Following particularly intense fisheries in summer 1999, attempts to feed on Spisula in winter 1999/2000 failed. It is hypothesised that overfishing of mussels and cockles in the Wadden Sea in the early 1990s resulted in structurally reduced food resources, contractions of the foraging area of common eiders, and increased use of secondary prey in the North Sea.     

Food-web traits of protected and exploited areas of the Adriatic Sea

This study presents a comparative analysis of protected and exploited Mediterranean Sea food webs using standardized ecological models of two ecosystems: the Central-North Adriatic Sea (highly exploited) and the Miramare Natural Marine Reserve (Northern Adriatic Sea, protected since 1986). Food webs are analysed in terms of structural and functional traits including trophic levels, transfer efficiency, trophic role of species and keystoneness, trophic spectra and other synthetic ecological indicators. Our results highlight similarities between food webs of the Adriatic Sea, differences that are likely due to the impact of fishing and differences that should be related to other factors. Analysis of biomass distribution along functional groups and of trophic spectra indicates that protected area presents higher mean trophic level of the community, higher biomasses, lower production and generally lower transfer efficiency than fished area. Our results indicate that measures of food web complexity (system omnivory index and ascendency), as well as pelagic/demersal and fish/invertebrates biomass ratios are higher in the protected area than in exploited ecosystem due to fishing-induced changes. Thus, this study highlights that marine protected areas can efficiently contribute to maintain structural and functional traits of marine ecosystems.     

不同规模农户生产技术效率及灌溉用水效率差异研究-- 基于内陆干旱区农户微观调查数据

水资源短缺已成为制约内陆干旱区农业生产和经济社会可持续发展的关键因子。然而农户生产技术效率不高、灌溉用水效率低下、水资源浪费严重已成为不争事实。为此,基于农户这一微观视角,运用实证调查和定量分析相结合的方法,在黑河中游选择典型区域的甘肃省民乐县和临泽县进行了调查研究。结果表明,农户生产技术效率远高于其灌溉用水效率,民乐县和临泽县总体样本农户的平均生产效率分别为83.82%和83.16%,而其平均灌溉用水效率分别为24.54%和22.16%。这表明在现有技术条件和生产要素投入不变的情况下,若消除效率损失,民乐县小麦的单位产出可能增加16.18%,临泽县制种玉米的单位产出可能增加16.84%;同时也表明相对于现有生产条件下可行的最小水投入量,民乐县被访农户的小麦生产浪费了75.46%的水资源,临泽县被访农户的制种玉米生产浪费了77.84%的水资源。结果再次显示,农户生产低效主要是由生产技术非效率因素引起的,民乐县这一因素占73.45%,其余26.55%是农户控制不了的因素引起的;临泽县该因素占76.58%,农户控制不了的因素占23.42%。而且,不同经营规模农户生产技术效率和灌溉用水效率差异性明显。农户生产技术效率与经营规模呈现"倒U型",农户经营规模与其灌溉用水效率呈现同向变动趋势。最后就如何提高农户用水效率提出了几点政策措施。