新疆土著鱼类的数值分类

本文采用鱼类的３４个可数量化性状，借助微机，利用主成分分析法对新疆５１种土著鱼类进行数值分类，其结果可将新疆土著鱼明显地划分为：条鳅属鱼类，臀鳞鱼亚科鱼类，雅罗鱼亚科鱼类３个主要的群体。     

松花江哈段主要排污口污水对设置网箱中鱼类成活率的影响

用设置网箱的方式，监测松花江哈段主要排污口水质对鱼类成活率的影响。结果表明：未经处理的污水排入江中，明显的影响鱼类的生长，并且产生致死效应，城市污水集中处理十分重要。     

Metapopulation analysis indicates native and non‐native fishes respond differently to effects of wildfire on desert streams

Ash flows and flooding associated with wildfires represent important but understudied sources of disturbance for fish populations. Knowledge concerning these disturbances is especially limited for larger streams where warm water species dominate. Fire‐related disturbances have been hypothesised to differentially affect native and non‐native fishes, although this hypothesis has only been tested for salmonids. The objective of our research was to contrast effects of uncharacteristically large wildfires followed by flooding on metapopulations of native and non‐native fishes in the Gila River of southwest New Mexico. Probabilities of occupancy, colonisation and local extinction of fishes were calculated across sites before and during disturbance and were also measured across a broader spatial scale during disturbance to identify potential refuge locations. Occupancy was higher for native fishes than non‐natives, but multiple wildfire and flood events increased extinction probabilities of native species. Responses of non‐native species to wildfires were mixed; extinction of non‐native salmonids increased during disturbance, while extinction of several warm water species remained unchanged or decreased. Several undisturbed sites were poor refugia for natives as they were impacted by non‐native piscivores, dewatering, and fragmentation. However, despite exposure to multiple disturbances, sites located in large tributary and valley reaches were consistently occupied by native species, suggesting these habitats provided refugia. We suggest that management actions (forest thinning; prescribed burning) that restore a more natural disturbance regime of small and less severe fires coupled with habitat remediation activities (non‐native removal; decreased water withdrawal; improved connectivity) might diminish extinction risk for native fishes exposed to wildfire disturbance.     

Quantifying ichthyofaunal zonation and species richness along a 2800‐km reach of the Rio Chama and Rio Grande (USA)

Abstract – Ichthyofaunal zonation occurs when lotic fishes are partitioned into distinct assemblages, usually in response to longitudinally distributed habitats. Several studies have documented zonation within the Rio Grande, but this is the first to quantitatively test the zonation hypothesis along a continuous 2800‐km river profile, extending from the Rio Chama headwaters to the Gulf of Mexico. Using a large, multi‐source dataset, I detected three ichthyofaunal zones: a high gradient (～1.5%) ‘upper’ zone, a moderate gradient (～0.2%) ‘middle’ zone and a low gradient (<0.1%) ‘lower’ zone. Species richness was lowest in the upper zone and highest in the lower zone, and all zones contained large numbers of nonnative species. However, species richness did not accumulate in a consistent, downstream manner. Instead, it tracked local‐scale changes in mean annual discharge. This demonstrates the strong effect of river regulation and irrigation withdraws on fish diversity in the Rio Grande.     

The Palaeozoic, Mesozoic and Early Cenozoic fishes of Africa

Africa has provided many fossil fishes from sediments laid down over a 400 million year period. The large array of fossil fishes come from diverse localities throughout the continent, representing a variety of environments. The marine fossil fishes of Africa have not been reviewed as a whole, while the freshwater Cenozoic fishes of Africa were last reviewed over 25 years ago. Since that time, many new finds have increased our knowledge of the history of African fishes. This paper summarizes the known fish fossils, excluding otoliths, from marine and freshwater deposits throughout Africa from the Palaeozoic, Mesozoic and first part of the Cenozoic (Palaeogene). Much new work is ongoing, in areas such as Mali and South Africa, from which more information on the ichthyofaunas should come to light. New information presented here includes the Eocene site of Mahenge, Tanzania, from which have come the oldest known members of the family Cichlidae.     

太湖主要鱼类食物组成

根据2004年9-12月和2005年4月的调查,研究了太湖8种鱼的食物组成.结果表明:优势种鲚主要摄食枝角类、占食物个数比例89.77%±13.69%;太湖新银鱼主要摄食桡足类、占个数比例70.11%±10.57%;鲢、鳙主要摄食微囊藻、占食物体积比例90%以上;鲤食物中水生植物约占体积比例70%;鲫主要摄食微囊藻、占体积比例93.99%±3.34%;翘嘴红鲌、蒙古红鲌主要摄食鲚和小型鱼类.分析认为,随着太湖富营养化程度不断加重,以蓝藻为主的浮游植物食性鱼产力在快速增加,但实际渔获量以浮游动物食性鱼类为主.如2003年浮游植物食性鱼产力为10234t、占总鱼产力37.0%.而2004年实际渔获量中浮游动物食性鱼类占80%-90%,浮游植物食性鱼类渔获量仅3637.7t、占10.9%.因此,太湖现有鱼类群落组成和实际饵料构成是不吻合的.不仅如此,浮游动物食性鱼类数量的快速增加对浮游动物形成了巨大牧食压力,这更利于藻类繁殖.太湖鲫几乎完全以微囊藻为食物,可能对蓝藻暴发有抑制作用,应重新评价其对环境的影响.     

基于双正则化的图像超分辨率盲重建

图像超分辨率重建是利用数字信号处理技术由一系列低分辨率观测图像得到高分辨率图像。大多数重建算法假设成像系统的模糊特性也即点扩散函数(PSF)已知,然而实际的应用环境下PSF事先不知道或部分知道。为此,将未知PSF模型化,提出基于双正则化的图像超分辨率盲重建算法,并且正则化作用的强度随重建图像局部光滑程度的变化而自适应地改变,以便能保护图像细节同时抑制平滑区域的噪声。求解过程中采用交替最小化方法估计PSF参数和高分辨率图像,并随着迭代次数的增加逐步提高每次寻优的精度以节省计算开销。实验结果表明,该算法能够比较准确地估计出PSF参数并取得较好的图像重建效果。     

Present state and perspectives for the southern Brazil shelf demersal fisheries

The demersal fish stocks in southern Brazil were assessed from landings and catchper-unit effort data trends between 1975 and 1994, available information on the life history patterns, and population dynamics of the most important species. The fishing gears, mostly otter and pair bottom trawls in the 1970s, diversified towards double-rig trawls for fish and shrimp and bottom gill nets in the mid 1980s, and bottom longlines in the upper slope in the early 1990s. There were also some less successful attempts with traps for fish and crabs. The demersal fisheries are more intensive in winter when migratory species move northward, associated with the seasonal displacement of the western boundary of the Subtropical Convergence. Landings between 1975 and 1994 were mostly of sciaenid fishes (>70%) and elasmobranchs (10%) and oscillated around 59 000 t. There was not a decrease in total landings but a shift from more to less exploited stocks. Since 1989, 4% of the landings came from depleted stocks of Pagrus pagrus (L.), Netuma barba (Lacépède), Pogonias cromis (L.) and Rhinobatos horkelli (Muller & Henle); 37% from overexploited stocks: Micropogonias furnieri (Desmarest), Paralichthys patagonicus Jordan, Squatina guggenheim Marini, and Galeorhinus galeus (L.); 24% from heavily exploited stocks of Umbrina canosai Berg, and Macrodon ancylodon (Bloch & Schneider); and 35% of Cynoscion guatucupa (Cuvier) and small stocks with unclear status. The demersal fisheries are virtually unmanaged and future landings are expected to decrease if fishing pressure remains high. Effective management will require the participation of all three countries in the region because most of the stocks fished in southern Brazil are shared with Uruguay and Argentina.     

几种近海底层鱼类和中上层鱼类隐蔽伪装色的比较

为了探明近海不同生态类型鱼类隐蔽伪装色的差异,研究了6种中上层鱼类和5种底层鱼类的隐蔽伪装色,结果表明:无论近海中上层鱼类(包括大甲鲹Megalaspis cordyla、斑■Hemiramphus far、五条■Seriola quinqueradiata、竹■鱼Trachurus japonicus、蓝圆鲹Decapterus maruadsi、蓝点马鲛Scomberomorus niphonius)还是近海底层鱼类(海鳗Muraenesox cinereus、斑尾复虾虎鱼Synechogobius ommaturus、带鱼Trichiurus japonicus、单角革鲀Aluterus monoceros、龙头鱼Harpadon nehereus),黑色素细胞和黄色素细胞均为背部多腹部少,差异显著;相比近海底层鱼类,近海中上层鱼类背腹部体色差异更加明显,中上层鱼类黑色素细胞和黄色素细胞差异更大;虹彩细胞在背腹部皮肤中都存在,而近海底层鱼类的腹部主要为虹彩细胞;红色素细胞在近海底层鱼类中很少存在,但在中上层鱼类中较多。上述结果显示,鱼类背部体色的深浅主要与皮肤中黑色素细胞和黄色素细胞的数量有关,腹部体色的形成主要与虹彩细胞的多少有关。     

Egg size and its relationship with fecundity,newborn length and female size in Cuban poeciliid fishes (Teleostei: Cyprinodontiformes)

Abstract – This study describes the relationship between egg size (ES) and brood size (BS), newborn length (NL) and female total length (FTL) in ten species of Cuban poeciliids. Variability and the level of association among variables are analysed and comparisons of ES among species established. Egg size has the lowest variability among the analysed variables and in most species is not correlated with BS, when the effect of FTL is controlled. Cuban poeciliids, thought to be primarily lecithotrophic, can be separated in two groups according to ES, NL and BS relative to FTL. One such group inhabits mountain streams and produces large eggs and small broods. The other group is distributed in lowland wetlands and produces small eggs and large broods. In Cuban poeciliids, ES and NL are highly correlated, which suggests adaptive value for ES.