淡水养殖梭鱼的人工繁殖机理

1982～1986年;作者采用外源药理学方法,使淡水养殖梭鱼(S‰0.297-0.569)克服了“淡水不育症”,雌鱼性腺成熟率85％以上,完全取代了“海水过渡”。在人工催产中又克服了排卵机制的障碍及胚胎对环境的不适应,并对梭鱼亲鱼血清激素含量进行放射免疫(RIA)测定及电子显微镜对梭鱼脑垂体亚显微结构进行观察。提出梭鱼存在血脑屏障。     

Turbine entrainment and passage of potadromous fish through hydropower dams: Developing conceptual frameworks and metrics for moving beyond turbine passage mortality

Potadromous fishes are vulnerable to involuntary entrainment through hydropower turbines. However, turbines can also provide a downstream passage route for potadromous fish. Here, we review evidence for turbine entrainment and passage in potadromous fish, and evaluate the effects of these processes on upstream and downstream populations. We develop conceptual frameworks and metrics to quantify vulnerability to turbine entrainment removals, and to quantify the efficiency of turbines as a downstream passage route. We highlight factors that influence these processes and provide case‐studies demonstrating their applicability. We found that juvenile potadromous fish are being entrained through turbines at rates high enough to impact upstream populations. Given that juvenile passage survival is often high, we argue that turbines provide an important downstream passage route for potadromous fish. We show that entrainment vulnerability is likely a function of interactions between in‐reservoir fish behaviour, habitat configuration and operations and thus not well captured by passage mortality estimates. Similarly, we show that while passage mortality can limit downstream passage efficiency, passage success is also dependent on reservoir and forebay navigation, along with survival and fitness in the downstream river. We advocate for a shift in focus away from estimates of passage mortality and injury, which have previously accounted for the majority of turbine passage research. Instead, we recommend an approach that focusses on quantification of the factors that influence downstream passage efficiency and entrainment vulnerability. Moreover, we highlight the need to better understand the broader scale impacts of these events on upstream and downstream populations.     

Promoting connectivity between priority freshwater sites for conservation in intermittent hydrological systems

1. Systematic conservation planning in freshwater ecosystems faces multiple challenges because of the dynamic nature of rivers and their multiple dimensions of connectivity. In intermittent hydrological systems connectivity is functional when water is available, allowing the exchange of aquatic individuals between isolated freshwater ecosystems. Integrating these isolated systems in their hydrological context is essential when identifying priority areas for conservation, in order to try to minimize the propagation of threats into target water bodies (management units) from the surrounding landscape.
2. Here, the use of a systematic planning approach is demonstrated to identify a set of priority management units to preserve freshwater biodiversity in an arid system of fragmented water bodies immersed in a landscape subject to a range of impacts.
3. Twenty-six water-dependent taxa from 59 mountain rock pools (gueltas) of three southern Mauritanian mountains were used as a case study. A conservation planning tool (marxan ) was used to find priority conservation areas to integrate intermittent hydrological systems in their hydrological context, promote connectivity, and minimize the downstream propagation of threats. Three types of connectivity were analysed: (i) no connectivity, (ii) connectivity between gueltas, and (iii) connectivity between gueltas and sub-catchments.
4. Considering different types of longitudinal connectivity affects the number and spatial allocation of the priority gueltas selected, and the conservation status of the gueltas and their upstream areas. Incorporating connections between gueltas and upstream locations in the modelling resulted in the selection of gueltas in areas with a low human footprint and in the increased connectivity of the solutions.
5. The results obtained revealed important locations for local biodiversity conservation, and the method presented can be used when assessing the propagation of potential waterborne threats into isolated management units. The framework developed allows connectivity to be addressed in conservation planning. It can be replicated in regions with similar isolated habitats that connect through intermittent hydrological systems and can also be applied to lateral and vertical hydrological connectivity.

     

“太湖1号”杂交青虾规模化繁育技术研究

利用53hm2标准化鱼池,采用雌雄亲虾同池的放养模式与集中投放抱卵虾孵化培育模式2种模式进行“太湖1号”杂交青虾的规模化繁殖试验。结果显示,本期共繁殖生产虾苗33533．86万尾,31878．33kg。雌雄亲虾同池培育的产苗量比集中投放抱卵青虾培育的产苗量要低36．49～69．26kg／hm2,或132．85万。143．607万尾／hm2,苗种规格大小差异大。雌雄亲虾同池培育的捕苗时间从7月18日到8月25日,共计38d,集中投放抱卵亲虾培育池的苗规格较一致,捕苗时间为期25d,捕捞时间缩短了13d。这表明,集中投放抱卵虾孵化培育模式可作为青虾规模化繁殖生产的优选方式。     

Bleeding of Farmed Atlantic Cod: Residual Blood,Color, and Quality Attributes of Pre- and Postrigor Fillets as Affected by Perimortem Stress and Different Bleeding Methods

The main objectives of the study were to (a) assess the effect of perimortem stress on blood drainage, (b) compare the efficiency of gill cutting and direct gutting as bleeding methods, and (c) compare pre- and postrigor filleting strategies for presence of residual blood in Atlantic cod fillets. Anesthetized cod had significantly higher drainage of blood compared to stressed fish. Nevertheless, the visual assessments of residual blood were not affected by stress or bleeding method. Some minor, but significant, differences between pre- and postrigor fillets were found. Stressed fish were initially less light in color than those unstressed, but after ice storage there was no noticeable difference. However, initially, the largest difference in fillet color was due to different bleeding methods. Fillets cut from fish subjected to gill cutting were lighter and less red in color than those bled by direct gutting. After 7 and 21 days of storage, the color differences observed in fresh and salted fillets, respectively, were mainly due to the different rigor status when they were filleted, indicating that fillets cut postrigor were superior to fillets cut prerigor. Prerigor filleting resulted in lower water holding capacity after ice storage in anesthetized, direct gutted cod.     

Environmental correlates of body size distribution in Cyprinidae (Actinopterygians) depend on phylogenetic scale

The pattern of increasing species body size with increasing latitude has been noticed in different groups of animals. Here, we used seven key environmental factors and independent contrasts to assess body size latitudinal clines in Cyprinidae at two phylogenetic levels (inter‐ and intragenera), which were defined using a genus‐level supertree. Model selection procedures revealed that environmental factors shaping body size variation in Cyprinidae differed according to the phylogenetic scale considered. At the higher phylogenetic level, we found that both temperature (negative effect) and habitat availability (positive effect of drainage basin surface area) constituted mechanistic explanations of large‐scale body size distribution. No temperature‐related body size cline was observed at the intragenus level. Instead, competitive interaction (negative effect of species richness), habitat availability (positive effect of drainage basin surface area), migration ability and available energy (positive effects of glacial coverage and actual evapotranspiration) constitute alternative explanations at this lower phylogenetic scale. We conclude that (i) at the intergenus level, cyprinids do show a tendency to be smaller at high temperatures and larger at low temperatures, (ii) this tendency no longer exists at the intragenus level, (iii) latitude per se is a weak predictor of body size clines whatever the taxonomic level analysed, (iv) generalising geographical body size patterns may be rendered difficult by the superimposition of a series of mechanisms across different taxonomic scales, and (v) habitat size, here acting positively at both taxonomic scales, may play a major role in shaping riverine species body size clines.     

罗氏沼虾消化系统组织学的光镜与扫描电镜观察

本文进行了罗氏沼虾（Macrobrachiumrosenbergii）消化系统的光镜组织学和扫描电镜研究。观察发现，罗氏沼虾的贲门胃内无齿，胃壁背、腹面的一定部位有角质板的特殊结构。中肠很长，占据头胸部的后半部分和腹部的大部分；中肠上皮细胞的游离端和中肠腺小管细胞的游离端均有纹状缘，无角质膜。后肠很短，无纹状缘。消化道上皮细胞有无纹状缘是区分中肠与前、后肠的重要标准之一。     

Blood chemistry values of juvenile red pacu (Piaractus brachypomus)

Abstract: Blood samples were collected from 29 juvenile red pacu ( Piaractus brachypomus ), ornamental freshwater fish, to establish baseline blood chemistry values. Mean (minimum-maximum) values, obtained by automated bichromatic analysis and ion selective electrode analysis, were as follows: sodium, 150.4 (146–159) mmol/L; potassium, 3.93 (2.7–5.0) mmol/L; chloride, 138.7 (128–150) mmol/L; total CO₂, 7.5 (6–10) mmol/L; albumin, 0.86 (0.5–1.0) g/dL; lactate dehydrogenase, 237.8 (65–692) IU/L; aspartate aminotransferase, 49.1 (0–125) IU/L; creatinine, 0.31 (0.2–0.4) mg/dL; calcium, 10.80 (9.5–12.5) mg/dL; anion gap, 6.89 (1.2–12.5) mmol/L; and phosphorus, 7.29 (4.1–8.9) mg/dL.     

养鱼池塘机械拖网捕鱼系统的设计与试验

针对目前池塘拖网捕鱼作业完全靠人力,工作效率低的问题。通过在池塘两侧设置网具引导钢丝绳,利用液压绞车及拖引装置实现连续拖网的方法,开发了一套池塘机械拖网捕鱼系统。试验结果为：拖网系统在规格为50 m×100 m池塘进行机械拖网试验,拖网速度为10 m/min,拖网人员由12人减少至5人,拖网捕鱼效率约64.8%。机械拖网大幅减少了作业人数,运行稳定,适用于各类矩形池塘的捕捞作业。