An Investigation into Behavioural Indicators of Stress in Juvenile Scallops

Recessing and righting behaviour requires a big energetic cost to scallops and if the animals are already weakened by the stress of handling, exposure to air and transport they may find if difficult to carry out these manoeuvres. The objectives of this study were to determine the preferred sediment of scallop (Pecten maximus) spat and to determine the recessing and righting behaviour of spat under a dessication stress. The results showed that the time taken to recess was indirectly proportional to the mean sediment size of the sediment. When using the 'preferred' sediment, recessing and righting speed was indirectly proportional to the degree of exposure to air experienced by the animals. Thus by removing seasonal and size variables we were able to demonstrate a clear relationship between quality and behaviour in juvenile scallops. This test is therefore not only sensitive to changes in spat quality but is also a very quick and simple test to perform.     

Coupling hydrodynamic and individual‐based models to simulate long‐term larval supply to coastal nursery areas

For many marine fish species, recruitment is strongly related to larval survival and dispersal to nursery areas. Simulating larval drift should help assessing the sensitivity of recruitment variability to early life history. An individual‐based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the population scale in the eastern Channel on a 14‐yr time series, from 1991 to 2004. The IBM allowed each particle released to be transported by currents from the hydrodynamic model, to grow with temperature, to migrate vertically giving stage development, and possibly to die according to drift duration, representing the life history from spawning to metamorphosis. Despite sensitivity to the larval mortality rate, the model provided realistic simulations of cohort decline and spatio‐temporal variability of larval supply. The model outputs were analysed to explore the effects of hydrodynamics and life history on the interannual variability of settled sole larvae in coastal nurseries. Different hypotheses of the spawning spatial distribution were also tested, comparing homogeneous egg distribution to observation and potential larval survival (PLS) maps. The sensitivity analyses demonstrated that larval supply is more sensitive to the life history along larval drift than to the phenology and volume of spawning, providing explanations for the lack of significant stock–recruitment relationship. Nevertheless, larval supply is sensitive to spawning distribution. Results also suggested a very low connectivity between supposed different sub‐populations in the eastern Channel.     

A reliable method for the induction of experimental furunculosis

Abstract. A series of experiments were carried out to assess the reproducibility of a bath challenge model to induce experimental furunculosis. The challenge method was shown to reliably induce a control mortality of 78.9 ± 3.8%. Although the method was shown to be robust, some tanks failed to achieve an acceptable control mortality. The reasons for this are unclear; however, the failure of a tank to induce a satisfactory control mortality is related to a rapid disappearance of the initial inoculum. The reason for the disappearance of the inoculum appears to be related to the presence of hydrophobic regions in the challenge tank.     

Design evaluation of a fish cage mooring system with different bridle line connections using model experiments and simulations

Because fish cage systems are strongly influenced by various marine environmental conditions such as currents and waves, structural safety design is of crucial importance during their installation. It is particularly important to design a technical solution for a mooring system. In this study, we designed four types of fish cage systems with different bridle connection arrangements (two single-rope and two multiple-rope connection methods) to evaluate the structural safety of fish cage systems based on the bridle connection arrangement and to propose an efficient design direction. The level of the structural safety of the fish cage system in terms of the resistance force, shape, and inside volume reduction ratio was found to vary according to the position of the frame lines connected to the bridle lines, the number of bridle lines, and the angle between the frame line and the direction of currents and waves. Improved structural safety was observed when the bridle lines were connected to the midpoints of the frame lines compared to those connected to the vertices, and the multiple-rope connection method was found to provide higher structural safety than the single-rope connection method. Increased fish cage system structural safety was also confirmed when the frame line orientation was 90° to the direction of currents and waves compared to that at 45°. From these findings, it can be concluded that the structural safety of a fish cage system can be improved by using multiple bridle lines to disperse the tension of the mooring lines connected to the frame lines and by installing the fish cage with the frame lines aligned at an angle that minimizes the projected area exposed to currents and waves. Moreover, the simulation technique presented in this study is expected to contribute to the efficient evaluation of the structural safety of various fish cage mooring systems designed using multiple-rope connection methods, accounting for the number and position of bridle lines connected on a frame line.     

Product differentiation,labelling and quality approach: Developments and stakes in the French shellfish market

Abstract

France is one of the world's top producers of oysters and mussels by aquaculture with 140 000 tonnes of oysters, 60 000 tonnes of mussels and an ex‐farm turnover accounting to 350 million US$ in 1996. The French market is by far the largest in Europe for oysters and is supplied entirely by domestic production, with very little external trade. Conversely, the French market for mussels is a very competitive one, widely open to imports. Given the evolution of market conditions due to the development of supermarkets, to the competition of new value‐added products and to the modification of consumer habits, French oyster and mussel producers have begun to implement various strategies of product differentiation and quality approach. These numerous strategies, which are built on geographical origin, process of production or marketing promotion may induce confusion in the consumer's mind. A typology of these strategies has been drawn in order to clarify the situation and to assess their sustainability. Since any quality approach has a counterpart in terms of production costs, an enquiry has been carried out at the level of supermarkets in order to assess the price the buyers are ready to pay for labelled oysters and mussels. The results of this study show important variations according to the locality of the supermarkets, especially with regard to the distance to the coast and the size of the town. Contractual relationships between producers and supermarkets as well as better production organization prove to be important perquisites to ensure successful product differentiation and quality approaches.     

真鲷♀×黑鲷♂人工育苗技术研究

通过真鲷♀×黑鲷♂杂交,获得杂交F1.研究发现,杂交鱼苗在培育期间有3个死亡高峰;培育密度以1万～1.8万尾/m<'3>为合适,在此密度下培育至稚仔鱼最高培育成活率可达36%;在水温22～23℃,从初孵仔鱼到1 cm需27 d,水温17～18℃,从初孵仔鱼到1 cm需36 d.     

COMPETITIVENESS OF U.S. AQUACULTURE WITHIN THE CURRENT U.S. REGULATORY FRAMEWORK

Increased attention has been paid in recent years to both positive and negative effects of increasing numbers of regulations on businesses in the United States. The decline in U.S. aquaculture has been attributed in part to increasing volumes of imports and high feed prices. However, there is increasing concern that the U.S. regulatory environment, as compared to that of international competitors, may also have contributed to this decline. More than 1,300 laws apply to U.S. aquaculture and even though the majority has been issued by individual states and apply only to specific types of aquaculture businesses in that state, the cumulative regulatory burden has increased over time. Major compliance categories include: 1) environmental management; 2) food safety; 3) legal and labor standards; 4) interstate transport of aquatic products; 5) fish health; and 6) culture of commercially harvested species. A substantial portion of the regulatory burden is the managerial and labor time spent on compliance in addition to the direct cost increases. The streamlined one-stop process adopted in Norway appears to have allowed growth of aquaculture within a comprehensive regulatory framework, yet the lack of such a streamlined approach in the United States appears to have contributed to the decline of existing industries and to serve as a deterrent to investment in newly emerging technologies. Favorable regulatory environments in countries that export to the U.S. contrast sharply with the increasingly inefficient, cumbersome and/or restrictive U.S. environment. Such disparities have created competitive disadvantages for U.S. producers. Attention is needed by policy makers to search for streamlining mechanisms and by the scientific community to address the growing competitive disadvantage to U.S. aquaculture to respond to increased global demand for farmed seafood.     

The Achilles heel for spiny lobsters: the energetics of the non‐feeding post‐larval stage

Spiny lobsters are highly valuable seafood species that are captured and marketed in more than 90 countries. After more than 30 years of stable catches, spiny lobster fisheries in many parts of the world are declining due to decreased recruitment. The planktonic larvae spend up to 2 years in offshore waters, accumulating energy stores to fuel the non‐feeding post‐larva, or puerulus, to actively migrate onshore and settle. The total energy required by spiny lobster pueruli for cross‐shelf migration has not been accurately determined. Recent advances in larval culture have provided the opportunity for the first detailed examination of the swimming performance, respiratory metabolism and nitrogen excretion of spiny lobster (Sagmariasus verreauxi) throughout the puerulus stage. The routine and active metabolic rates of pueruli were lower than for most other decapod larvae, probably to provide greater energy efficiency. However, pueruli were found to have limited time, swimming ability and fuel for active cross‐shelf migration. It is estimated that S. verreauxi pueruli require at least 13.8 mg of stored lipid to provide sufficient energy (18.4% DW) to complete the puerulus stage and recruit to coastal habitats. The ability of the preceding phyllosoma larvae to accumulate these reserves, and the presence of favourable oceanographic conditions during the limited time available to the migrating puerulus, are both crucial to subsequent successful recruitment. Spiny lobster recruitment processes appear to be particularly vulnerable to changes in oceanic climate which is likely to contribute to the recent large‐scale declines in recruitment to valuable fished populations.     

Control of dissolved oxygen levels of water in net pens for fish farming by a microscopic bubble generating system

ABSTRACT:   A microscopic bubble generating system (MBGS) has been developed to control dissolved oxygen (DO) levels suitable for fish farming. The MBGS has been tested to confirm its capability in net pens. Water conditions in a fish farm were monitored every two hours from June to October 2004 by setting an online vertical profiling system (OVPS) close to the net pen. DO in the net pen water decreased to physiologically stressful levels for the fish during the night (4.84–5.51 mg/L), while the DO was kept in saturated conditions during the day, due to oxygen supply from phytoplankton. The MBGS was operated from the evening to the morning of the next day for 16 h, to successfully create DO-saturated conditions in the net pen water at night. By using microscopic bubbles during the warm seasons, DO levels in the net pen water could be improved to a level suitable for fish farming. However, the low DO levels (<5.0 mg/L) of the bottom water occasionally extended to the net pen layers, despite the supply of microscopic bubbles to the water. To maintain the DO of the net pen water at levels suitable for fish farming, DO supply to the net pen water and the bottom water needs to be increased, and the organically enriched sediment just below the net pens needs to be treated.     

基于马尔可夫过程的湖泊生态需水保障不确定性研究

湖泊生态需水对维持湖泊基本生态功能具有重要的作用，保障生态需水已成为湖泊生态保护的重要组成部分。目前湖泊生态需水的保障方法都是在同一时间尺度下维持一个确定的生态需水量；然而，湖泊水位是一个随机过程，湖泊生态状况与湖泊水位波动息息相关，仅保持湖泊在一个水位值不足以满足湖泊在不同时期的生态需水量；另一方面，生态系统的结果和功能在不断变化，导致湖泊的生态需水量也发生变化，只保障一个确定的生态需水量的方法不足以应对湖泊生态需水量未来可能存在的各种情况，也无法应对未来生态需水保障的不确定性。因此，亟需对湖泊生态需水进行不确定性研究，以保障不同时期的生态需水量。本研究以白洋淀为案例，将白洋淀水位划分成五个区间，代表五个水位时期，再将每个时期下的生态环境状况进行分析，得出每个时期有利于湖泊生物多样性的生态需水量。然后根据马尔可夫过程，利用改进加权马尔可夫链模型，计算出未来湖泊水位处于各个时期的概率，从而确定湖泊未来生态需水量的保障程度，对未来生态需水保障情况进行预测。     

Habituation and conditioning in gilthead sea bream (Sparus aurata): Effects of aversive stimuli,reward and social hierarchies

To tailor the farming environment to a fish species, we should understand the species‐specific responses to stimuli, including the degree of adaption and learning. Groups of gilthead sea bream were given a delay Pavlovian conditioning regime using a conditioning stimulus (CS) of light flashes signalling arrival of food. Controls were exposed to light flashes unrelated to feeding. Fish in both treatments showed an initial fear response of moving away from the CS combined with reduced swimming speed. In subsequent trials, the Control fish largely habituated the fleeing response but sustained to respond by reducing the swimming speed. The Conditioning fish also stopped to escape from the CS, but opposed to the Control group they gradually increased their swimming speed in response to the CS. In addition, the number of fish in the feeding/CS area increased and became similar to basal level after around 16 trials. A small and variable proportion of the fish displayed black vertical bands on their body and territorial behaviour, and a social hierarchy could interfere with the processes of habituation and conditioning. The swimming speed of the fish increased with number of dark individuals, but this was not found during the CS and the light stimulus thus seemed to overrule the effect of territorial behaviour. The persistent negative response to light flashes in the Control suggests that fish seemingly adapted to repetitive stressors are still in a state of alertness. The change in the response to light shows the potential for rewarding aversive stimuli to reduce stress.     

The influence of salinity on growth and structure of epidermal papillomas of the European eel Anguilla anguilla L.

Abstract. Papillomatosis of the European eel Anguilla anguilla L. occurs predominantly in waters of low to medium salinity (3–20%). Tumour-bearing eels were kept under laboratory conditions for several weeks in salt concentrations of 8, 15 and 30%. As opposed to those kept in freshwater, the experimental animals showed significant decreases in tumour growth rate. At the same time the tumour tissue underwent a marked redifferentiation, i.e. the originally poorly differentiated neoplastic tissue developed numerous mucous and club cells. The characteristic intercellular spaces of tumorous tissue disappeared with the formation of regular membrane interdigitations between adjacent cells. The nucleus to cytoplasm ratios of the neoplastic cells decreased to one-third of those of the untreated tumour. These changes resulted in a reversion of the neoplastic tissue to a structural condition essentially similar to that of normal epidermis. After a period of 2 to 3 months an adaptation to the altered salinity of the external medium was evident in that the tumorous tissue began to return to its original state.     

浙江省发展现代林业的科技需求分析

林业是一项重要的公益事业和基础产业,是国民经济的重要组成部分。在浙江省全面建设小康社会的历史进程中,林业承担着生态建设和林产品供给的重要任务。浙江省作为一个“七山一水两分田”的地区,森林资源持续增长,林业产业日益壮大。随着经济社会的发展,科技在林业发展的作用也日益突出。坚持“科技兴林”,是浙江省林业转型升级快速发展的动力。林业科技进步对促进农民增收致富、推进社会主义新农村建设,建设生态文明、构建社会主义和谐社会,推动经济社会又好又快发展发挥了重要作用。本文结合浙江林业发展的新形势,从提高森林培育技术、改善人居环境、林业转型升级和促进林农致富等方面,分析新时期发展现代林业的科技需求。     

旅游水产品品牌个性的构建——以浙江舟山旅游水产品为例

旅游产品是旅游业中一个非常重要的组成部分，旅游产品经营的好坏，是衡量其旅游业是否趋于成熟的重要标志。特点鲜明、富有个性的旅游产品，不仅会给旅游区带来丰厚的经济效益，而且还能够提升旅游目的地的声誉和知名度。但是由于观念上的落后，很多企业旅游产品的经营者只重视质量，在很大程度上限制了旅游产品品牌个性的发展。文章以旅游水产品为例，从品牌个性构建角度出发，分析了影响品牌个性的因素，并从八个方面结合水产品的个性，提出如何构建旅游水产品品牌个性，为水产品企业经营者提供品牌建设思路。     

Modification of the global coagulation tests for the dog. Significance for the monitoring of heparin therapy]

When the global coagulation tests Quick's test, aPTT and thrombin time are carried out on dogs using reagents from the human medical sector according to the manufacturer's instructions, they react insensitively to deficiencies of the corresponding coagulation factors or to the presence of fibrin degradation products. In the present study it was attempted to develop sensitive global tests for the dog by modifying these tests. The Quick's test reacted apparently more sensitively after a 1:4 dilution of the test plasma with physiological saline solution. The sensitivity of the aPTT was demonstrated by the addition of BaSO4-adsorbed plasma to normal plasma. It seems to be particularly advantageous to combine a 1:3 plasma dilution with a reduction in the CaCl2-concentration to 5 mmol/l. Likewise, plasma dilution allows the thrombin time to react more sensitively in the presence of increased concentrations of fibrin degradation products. The aPTT and thrombin time are, as in human beings, suited for the control of a heparin therapy. However, since prolongation of the coagulation times is considerably dependent on the test chosen, the heparin sensitivity of the test should be determined in vitro prior to use.     

Potential movement of fish and shellfish stocks from the sub‐Arctic to the Arctic Ocean

An assessment of the potential for 17 fish or shellfish stocks or stock groups to move from the sub‐Arctic areas into the Arctic Ocean was conducted. A panel of 34 experts was convened to assess the impact of climate change on the potential movement of the 17 stocks or stock groups. The panel considered the exposure of species to climate change, the sensitivity of species to these changes and the adaptive capacity of each stock or stock group. Based on expert opinions, the potential for expansion or movement into the Arctic was qualitatively ranked (low potential, potential, high potential). It is projected that the Arctic Ocean will become ice‐free during the summer season, and when this happens new areas will open up for plankton production, which may lead to new feeding areas for fish stocks. Five stocks had a low potential to move to, or expand in, the high Arctic. Six species are considered as potential candidate species to move to, or expand in, the high Arctic. Six stocks had a high potential of establishing viable resident populations in the region. These six stocks exhibit life history characteristics that allow them to survive challenging environmental conditions that will continue to prevail in the north. This study suggests that several life history factors should be considered when assessing the potentiality of a species moving in response to changing climate conditions.     

渔业统计——渔业管理者和科学家的一个重要工具

FISHERIES STATISTICS： AN IMPORTANT TOOL FOR MANAGERS AND SCIENTISTS This presentation focuses on the type of information collected through fisheries statistics that could be useful to scientists and fisheries managers. In Norway the use of fisheries statistics as an analyzing tool for marine scientists can be dated back to around 1973. At that time the Directorate of Fisheries started to computerize information from logbooks of the trawl fleet. The fisheries managers started to use fisheries statistics as an analyzing tool by the late 1970's. Once again the computerization of sales notes information together with additional statistical information, enabled the manager to regroup the information according to new problems to be analyzed and new questions to be answered.     

A static analysis of the tension and configuration of submerged plane nets

A non-linear finite element method is employed to determine the equilibrium configuration and tension distribution of a net set in a uniform current. The method models each mesh bar in the net as an infinitely flexible rope element connected at each end to other elements by a frictionless hinge. The Newton-Raphson method is used to solve the basic non-linear simultaneous equations with respect to tension in mesh bar and knot displacements. Global convergence to the correct solution from an initially estimated state is ensured using a loading iteration in addition to the common configuration iterative procedure in order to accurately model the shape-dependent characteristic of hydrodynamic forces. The method is shown to predict the shape and tension distribution of fishing nets with reasonable accuracy in the case examined in the present study.     

增氧机定时增氧及自动保护系统

结合养殖池塘生物增氧的实际要求，我们研制出一种池塘增氧机自动控制系统，可根据用户的实际需要任意设定增氧时间与自动重复启动间隔时间，在断相、过载的情况下能自动切断电源，对增氧机电机起到保护作用。     

饥饿对褐菖鲉消化道组织及肌肉营养成分的影响

在室内可控环境下对褐菖鲉进行了不同饥饿时间处理,通过分析饥饿对褐菖鲉消化道指数及肌肉成分的变化情况,研究了饥饿对褐菖鲉消化道指数及肌肉成分的影响.褐菖鲉在饥饿胁迫下,随着饥饿时间的延长,其肠道萎缩,比肠长逐渐变小,与对照组相比,差异显著(P＜0.05);比肝重、比胃重、比幽门重指标均随着饥饿时间的延长而下降,其中比肝重下降幅度最大,饥饿21d的比肝重与对照组相比下降了85.033%;饥饿对褐菖鲉肌肉中水分、蛋白质、脂肪和灰分含量变化有显著影响,蛋白质、脂肪含量皆显著下降(P＜0.05),水分含量显著增加(P＜0.05),而灰分含量变化不大,差异并不显著(P＜0.05).