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。     

The trend of lessepsian fish populations with an emphasis on temperature variations in Iskenderun Bay,the Northeastern Mediterranean

The fish assemblages of the Eastern Mediterranean are highly variable owing to the Lessepsian migration. So far, there has been limited discussion about the temporal variation of Lessepsian populations, which may be a key to better understanding the establishment, persistence and spreading dynamics of these species. The objective of this study was, therefore, to develop an understanding of inter‐annual variations of Lessepsian fish populations through investigating the effects of climate conditions. For this purpose, we evaluated the data obtained from the seasonal bottom trawl surveys conducted over the course of 12 years, from 2004 to 2015, at the infra‐littoral zone of Iskenderun Bay. Our results indicated that Lessepsians constituted 27%, 62% and 85% of total teleost fishes in the number of species (LS‐%), biomass (LW‐%) and abundance (LN‐%), respectively. The linear trends showed that the dominance of Lessepsian fishes increased with annual rates of 1.9 (p < .01, LS‐%), 2.77 (p < .01, LW‐%) and 1.43% (p < .05, LN‐%) per year during the study period. In contrast, seasonal trend decomposition based on GAMMs revealed that the true shape of trends was non‐linear. The majority of the new Lessepsians entered the study area after 2009 when warmer conditions prevailed. Those new invaders such as Nemipterus randalli, Pomadasys stridens and Apogon smithi successfully settled in a short time and remarkably altered the composition of fish assemblages after 2010. We found that variations of lessepsian fish assemblages were correlated with the increase of annual minima and average values of sea surface temperature.     

Dams in the Amazon: The importance of maintaining free-flowing tributaries for fish reproduction

1. Free-flowing tributaries are important for the maintenance of fish diversity in dammed systems. In relation to the reproduction of fish species, the role of a free-flowing tributary was evaluated and compared with that of a dammed tributary downstream of large dams in the Madeira River, one of the main tributaries of the Amazon River.
2. Two hypotheses were tested: (i) the densities of the ichthyoplankton differ between the dammed and the free-flowing tributaries; and (ii) the free-flowing tributary contributes a greater diversity of fish larvae species to the assemblage structure of the main stem than the dammed tributary.
3. Fish eggs and larvae were sampled at five sites: one in each tributary (Jamari – dammed – and Machado – free-flowing) and three in the main stem (Madeira River), upstream and downstream from the mouth of each tributary.
4. Fitted Bayesian models showed that the densities both of eggs and larvae were more than twice as high in the free-flowing tributary than in the dammed tributary. The results also indicated that the free-flowing tributary makes a major contribution to the fish assemblage structure of the Madeira River, whereas the dammed tributary does not have a significant influence on the main stem assemblage structure.
5. The results demonstrate the importance of conservation and maintenance not only of the Machado River but also of other free-flowing tributaries in dammed basins, especially those basins with high biodiversity, such as the Amazon. Moreover, this study helps inform the decision-making process regarding the location of new dams, which is critical in fish diversity conservation.

     

Length–weight relationships for 21 coastal fish species of the Azores, north-eastern Atlantic

Length–weight relationships were estimated for 21 coastal fish species of the Azores, namely Abudefduf luridus, Bothus podas, Chromis limbata, Coris julis, Diplodus sargus, Echiichthys vipera, Gaidropsarus guttatus, Labrus bergylta, Mullus surmuletus, Phycis phycis, Pomatomus saltator, Sarda sarda, Scorpaena maderensis, Scorpaena notata, Seriola rivoliana, Serranus atricauda, Sparisoma cretense, Sphyraena viridensis, Synodus saurus, Thalassoma pavo and Trachinotus ovatus. Significant length–weight relationships were found for all species. Sexual dimorphism did not affect the length–weight relationships, except in the cases of S. cretense and C. julis. Length–length equations for converting size measurements (standard length (SL) and fork length (FL) to total length (TL)) are also presented for all fish species.     

活鱼提升机电器控制电路的设计

本文介绍了真空静压活鱼提升设备中自动化电器控制的设计,叙述了实现自动控制的功能要求,电路设计,工作原理和部件的选择,并根据试验找出了产生问题的原因和解决方法。     

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.     

东海区主要经济鱼类开捕规格的初步研究

根据1997-2000年东海区底拖网渔、№资源调查资料，以Beverton—Holt模型的单位补充量渔获最方程估算东海区18种主要经济鱼类的最适开捕年龄。运用von Bertalanffy，丰长方程估算最适开捕体长。结合鱼类生长的拐点年龄、临界年龄和初届性成熟年龄的体长，以及各鱼种实测最小性成熟体长，确定开捕规格。结果表明，目前东海区产量较高的带鱼（Trichiurus japonicus）和小黄鱼（Larimichthys polyactis）的建议开捕规格分别应为体长230mm和170mm。调整后的开捕规格与旧开捕规格相比，带鱼、短尾大眼鲷（Priacanthus macracanthus）、灰鲳（Pampus cinereus）、自姑鱼（Argyrosomus argentatus）均有所增大，小黄鱼、银鲳（Pampus argenteus）的开捕规格有所减小，变化较小的有蓝点马鲛（Scomberomorus niphonius）、日本鲭（Somber japonicus）、慌圆鲹（Decapterus maruadsi）等。建议以这18种主要经济鱼类为指标种类，制定新的法定开捕体长和幼鱼比例检查措施，实现东海区渔业资源的可持续利用。     

海洋小型鱼类研究进展

海洋小型鱼类对整个渔业资源变动起到指示作用,而且对经济鱼种资源变化有着重要的意义。着重论述了海洋小型鱼类的研究现状,其中包括海洋小型鱼类分布与环境关系、渔业生物学、资源数量评估的研究,并论述其将来研究的主要方向。     

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.     

Histopathology of respiratory organs of certain air-breathing fishes of India

Air-breathing fishes have evolved bimodal respiratory mechanisms for exploitation of water (through gills and highly vascularized skin) as well as atmospheric air (through aerial respiratory organs, ABO). Mucous cells in these respiratory organs of variously stressed fishes exhibit periodic fluctuations in their density and staining properties. The main types of damage in the gills include congestion of blood capillaries (BLCs), periodic lifting and sloughing of respiratory epithelia of the secondary lamellae causing haemorrhage, extensive fusion of secondary lamellae and hyperplasia of the respiratory epithelia due to uncontrolled regeneration leading to asphyxiation, altered excretion, and death of the fish. Haemolysis has also been observed following lead exposure. The damage in the ABO of Heteropneustes fossilis includes sloughing of the epithelial cells, leading to haemorrhage causing decreased red blood corpuscles density and degeneration of the secondary gill lamellae with reduced respiratory area. Subsequent hyperplasia of the respiratory epithelia and fusion of gill lamellae increase the respiratory barrier distance. The BLCs often bulge out and protrude into the lumen, bringing blood nearer to air. The ladder-like pillar cell (PLC)-BLC components of the gill lamellae frequently collapse. Damage to the ABO of Channa striata is less severe. Often haemorrhaging due to bursting of extensively stretched BLCs causes aerial respiratory failure. Chloride cells of the ABOs also show hyperplasia. While the highly mucogenic epidermis of C. striata shows less damage, the epidermis of Clarias batrachus and H. fossilis shows severe wear and tear, sloughing, and haemorrhage. Side-by-side regeneration continues, causing altered histomorphology of the epidermis. The different gland cells also show periodic fluctuations in their density and staining. The dermis also shows severe damage with loosening of their connective tissue fibres. These fibres give stronger reactions for sulfated mucin that not only retain additional water molecules for continuance of skin breathing, but also bind the toxic ambient pollutants.