对改革桁拖网设计制作的建议

十年前,正当我国近海的渔业资源处于严重衰退,捕捞经济效益处于逐年下降之际,江苏省海洋水产研究所研制的双囊桁拖网捕虾作业获得成功,并迅速推广使用.减轻丁东黄海传统捕捞对象的压力。任何渔业资源都不可能长期取之不尽,随着捕捞强度的增加,作业方式也得改变。近几年来,数千条机动渔船集中在江浙沿海进行桁拖网捕虾作业,使渔场越来越拥挤.特别是一些大马力渔船也改用桁拖网作业,捕虾的经济效益越来越差。据上海水产大学季星辉等人计算,一     

南海海域伏季休渔趣谈

小鱼：妈妈，这是怎么回事啊?最近这附近一艘渔船也看不见，不是发生了什么事吧?大鱼：放心，孩子。这是休渔。小鱼：哦!休渔……妈妈，休渔是怎么回事?大鱼：休渔就是拖网、围网及掺缯作业渔船不能进海区捕鱼。     

新型扫描声纳

最近韦斯麦公司研制的SS165型扫描声纳已用于商业性捕捞作业中。捕鱼、捕虾和捕蟹的渔民能够在254毫米的荧光屏上搜索目标和预先发现障碍物以避免渔具与障碍物接触，这样可在初步探索到的新渔区进行作业。围网船使用该声纳可确定鱼群的位置、鱼群的大小、深度和移动的方向、鱼群的密度，而不象垂直探鱼仪一样，需要渔船直接经过鱼群上方。     

应改变渔业船舶间内部识别灯的灯色

<正> 我国现有国营渔轮和群众机帆渔船几十万艘,作业区域分布在东、黄、渤、南海,在渔业生产旺季时,渔船高度集中,夜间,船上悬挂的捕鱼作业号灯、航行号灯、内部识别灯(或者称作内部联络灯)以及照明灯……几十海里,灯光一片,有时作业区域在主要航线上,使其他航行的船舶驾驶人员难以分辨渔船动态,不知是底拖网在作业还是从事上层网作业,是在放网还是起网,如何采取避让措施无所适从。     

影响拖网扩张的若干调整因子的探讨

<正> 底拖网是海洋捕捞生产的主要作业工具之一,历史悠久。由于拖网渔具具有作业主动灵活,捕捞效率高等优点,历来在国内外渔业生产中占有相当重要的地位。拖速与网口扩张的矛盾是渔具设计的关键所在,长期以来,海洋渔业工作者从多方面进行了理论探讨和实践尝试,取得了一些有益于生产的宝贵经验。其中,广为人们熟悉的疏目拖网是从改进     

国内外中层拖网的状况和发展

中层拖网在渔业上的应用是比较晚的。40年代末,北欧的丹麦、挪威、瑞士等国开始用小型渔船进行了双船中层拖网作业,以后通过技术上的不断改进,使之成为在北海中、南部、斯卡格拉克海峡等一带捕捞鲱鱼的主要作业方式。单船中层拖网是西德于60年代获     

dBASEⅢ在拖网数据库中的应用

<正> 建立拖网数据库系统的目的与意义拖网是我国海洋渔业生产中渔获量最大的一种渔具,因此,对拖网的分析研究、改进和设计乃是一项十分重要的工作.建立拖网数据库系统是为尽可能多的将我国各沿海省市国营渔业公司在生产中使用的拖网数据存贮于该系统中,除了在建立本系统时已存贮的拖网数据外,该系统还能方便地添加新的拖网数据,能在所存贮的全部拖网记录中快     

东南太平洋智利竹筴鱼中层拖网捕捞技术

根据2001年7月至2002年8月我国渔船在东南太平洋的智利竹笑鱼(Trachurus murphyi)渔捞记录和现场收集的资料,对中层拖网捕捞技术进行了分析研究,结果表明：(1)中层拖网主要在夜间作业;捕捞水层主要集中在30～80m水深;网位与鱼群的相对位置可分为5种类型,即鱼群在网口的中间、上纲紧贴在鱼群的上部、下纲紧贴在鱼群的下部、鱼群在上纲的上部和鱼群在下纲的下部。(2)鱼群进网数量可根据网位仪映像加以判断。(3)网位(y)与曳纲长度(x)呈线性关系,其回归方程式为：y=0．4427x-36．604。(4)捕捞效率随拖网速度而增加。(5)较高捕捞效率的表层水温指标为11．5～13．5℃。根据研究结果还对我国今后在东南太平洋智利竹笑鱼捕捞技术改进提出合理化建议。     

闽南-台湾浅滩渔场单船拖网作业调查与分析

根据2009—2010年闽南-台湾浅滩渔场单船拖网作业监测调查资料和生产统计数据,阐明单船拖网作业的渔业地位、渔场分布、网具类型,着重分析该作业渔获种类组成及主要捕捞对象的资源动态。结果表明:单船拖网作业产量位居闽南-台湾浅滩渔场各种海洋捕捞作业的首位,大吨位、大功率渔船数量连续多年不断增长;渔具型式以有翼单囊网具为主;部分渔船使用的拖网网囊尺寸远远低于国家标准;带鱼、二长棘鲷幼鱼损害现象较为严重;秋季8—10月蓝圆鲹和鲐鱼群体绝大多数个体可达到最小可捕规格。调查研究结果还表明,2002年以来单船拖网渔业资源结构已发生较大变化,生命周期短、营养级较低的蟹类、枪乌贼类、乌贼类和虾类资源渔获比重显著增长;原优势种类绿布氏筋鱼资源已出现严重衰竭;二长棘鲷资源量逐年减少,渔获群体明显趋向小型化、低龄化。     

中层拖网试验研究

中层拖网是以中上层及近底层鱼类为捕捞对象,可根据鱼群垂直分布和移动任意改变拖曳水层的渔具。中层拖网在国外已是一种成熟的作业。目前正朝着网具大型化,网口部分网目超大型化的方向发展。因内一些研究单位曾做过中层拖网的试验研究并取得一定的     

When fish shoals meet: outcomes for evolution and fisheries

The mechanisms underlying the social structure of free‐ranging fish shoals have received little attention in comparison to functional studies on shoaling. Recently, however, a number of investigations, both in the marine and in the freshwater environment, have begun to address the underlying mechanisms by concentrating on interactions between free‐ranging shoals. The rates of shoal encounters can influence the opportunities for individual assortment by phenotype and selection of shoal size; act as a constraint on the observed patterns of shoal structure by restricting individual choice behaviour and were found to be high in several small freshwater species (where intershoal distances were small), but lower in marine species where shoals were more dispersed. The duration of encounters may play a role in that it affects both the time available for assessment (of the encountered shoal) as well as that for exchange of individuals. Scarce published information on the outcome of shoal encounters suggests that the outcome of shoal encounters is influenced by shoal composition but not by shoal size. Individual behaviour may have evolved to maintain shoal size when shoals encounter, but when fish populations are depleted by fishing, this trait can exacerbate range and stock collapse. Furthermore, an understanding of the dynamics of shoal encounters has important consequences for the evolution of reciprocal altruism and the transmission of information through social learning within populations. Finally, information on encounter rates between shoals and the number of individuals that are exchanged on such occasions could be important for making predictions about the spread of disease through fish populations.     

Leadership in fish shoals

Leadership is not an inherent quality of animal groups that show directional locomotion. However, there are other factors that may be responsible for the occurrence of leadership in fish shoals, such as individual differences in nutritional state between group members. It appears that front fish have a strong influence on directional shoal movements and that individuals that occupy such positions are often characterised by larger body lengths and lower nutritional state. Potential interactions between the two factors and their importance for positioning within shoals need further attention. Initiation of directional movement in stationary shoals and position preferences in mobile shoals need to be addressed separately because they are potentially subject to different constraints. Individuals that initiate a swimming direction may not necessarily be capable of the sustained high swimming performance required to keep the front position or have the motivation to do so, for that matter. More empirical and theoretical work is necessary to look at the factors controlling positioning behaviour within shoals, as well as overall shoal shape and structure. Tracking of marked individuals whose positioning behaviour is monitored over extended time periods of hours or days would be useful. There is an indication that shoal positions are rotated by individuals according to their nutritional needs, with hungry fish occupying front positions only for as long as necessary to regain their nutritional balance. This suggests that shoal members effectively take turns at being leaders. There is a need for three‐dimensional recordings of shoaling behaviour using high‐speed video systems that allow a detailed analysis of information transfer in shoals of different size. The relationship between leadership and shoal size might provide an interesting field for future research. Most studies to date have been restricted to shoals of small and medium size and more information on larger shoals would be useful.     

2006年夏秋季东海群系澳洲鲐数量分布特征

利用2006年7~11月大型机轮灯光围网在东海外海的生产资料,并结合生物学测定数据以及水温遥感数据,对夏秋季东海群系澳洲鲐数量分布时空变化特征进行了研究,并探讨了它们与海洋环境条件的关系。结果表明:夏秋季东海外海海域的澳洲鲐主要为索饵群体,它们的高度集群期主要在7~9月份,其中以8月份较为明显;10月份以后,由于鱼群开始进行越冬洄游,移动速度明显加快,虽然有偶尔的高度集群现象,但是持续时间较短。在地理分布上,7~8月份,澳洲鲐索饵群体的主要分布在125°00′E以西、28°00′N以南海域;9月份,鱼群重心向东北方向转移,范围为125°00′~126°00′E、28°00′~28°30′N海域;10月份相对于9月份鱼群重心向东转移50 n mile,群体向北移动达150 n mile左右;11月份以后,澳洲鲐群体向东北方向的对马海峡转移且可能至日本海越冬。群体结构分析表明,夏秋季澳洲鲐的个体逐月迅速增大,且增长量以7~8月份较大,以后逐渐下降。根据澳洲鲐的群体移动规律以及海洋环境条件的变化,认为东海群系澳洲鲐属于黑潮边缘种,其中心渔场的变动和黑潮的强弱具有密切的关系。     

深水网箱多波束水声鱼群状态监测仪的改进设计

针对离岸深水网箱养殖的鱼群安全问题,采用多波束水声技术监测鱼群状态的方法.结合信号处理技术、通用分组无线业务(GPRS)无线传输技术及串口通信技术,开发了一套多波束水声鱼群状态监测仪.监测仪完成1次网箱扫描只需5s;实现了监测数据的即采即发功能,提高了系统的实时性;改进了电路结构,降低了系统复杂度,减小了系统体积,降低...     

Evaluation of ageing accuracy with complementary non‐lethal methods for slow‐growing,northern populations of shoal bass

In the upper Chattahoochee River basin, where some populations of shoal bass, Micropterus cataractae Williams & Burgess, are imperilled, age and growth data are lacking. Age and growth of shoal bass in this basin were assessed with non‐lethal means using scales and mark–recapture. Mark–recapture data allowed for estimation of accuracy and determination of effects of any scale‐based inaccuracies on growth models. Scale‐based age estimates were accurate for 57% of the samples, and errors of 1 to 3 years included equal numbers of over‐ and underestimates of age. von Bertalanffy growth models based on scale ages were similar to those based on mark–recapture ages for ages 3–8 but noticeably divergent for younger and older fish. Scales provided estimates of longevity up to 12 years of age, and growth models produced from mark–recapture suggest scale ages underestimated age, especially for older fish. These populations of shoal bass live longer and grow slower than other populations, suggesting regional management strategies may be needed.     

捕捞网具逃逸死亡研究进展

幼鱼及非目标种类兼捕已成为许多网具作业共同存在的问题,提高网具选择性能是降低这种兼捕的重要途径。但是选择性能研究主要是基于从网具中逃逸后的鱼类较轻遭受到网具损害并最终存活。如果逃逸死亡率较高,即使选择性提高也是无宜的,因此应当将鱼类逃逸后生存能力作为网具改进效果的评价指标。本文主要由以下三个部分组成:(1)逃逸后死亡的主要影响因素概述,主要包括网具特征、作业时间、作业深度、渔获种类及体长、渔获量及环境因子等;(2)逃逸死亡对资源量和渔业管理决策的影响;(3)总结了近年来通过网具革新措施提高存活率的最新研究概况,如逃逸网片、分离栅及新型材料的应用等。综合分析,认为采取保护幼鱼和非目标种类的一系列措施尽管能够提高鱼类从网具的逃逸几率,但是并不能降低遭遇网具的概率,实施禁渔区、禁渔期制度管理,避免在幼鱼资源高密度区和产卵季节作业是降低这种未报告死亡的最重要的途径。     

A meta‐analysis of fish behavioural reaction to underwater human presence

In an increasingly anthropic world, humans have profound impacts on the distribution and behaviour of marine fishes. The increased human presence has modified fishes’ antipredator behavioural responses, and consequently flight decisions, as a function of their changed perceptions of risk. Understanding how fish react to human presence can help identify the most vulnerable functional groups/species and estimate impacts caused by human disturbance. Shoal and body size are known to influence fish flight initiation distance (FID; the distance between the predator and prey when the prey begins to escape); however, few studies attempt to test the moderators of these relationships. Here, we present a comprehensive meta‐analysis evaluating FID of fish in response to human presence. Specifically, we investigated six candidate moderators that could influence the relationship between FID with shoal and body size. Our results showed that individual fish size was strongly and positively correlated with FID and the most important moderator that explained the variance in individual body size‐FID relationship was shoaling behaviour. However, and somehow surprisingly, we detected no significant relationship between shoal size and FID. We discuss how these results can inform the development of fish conservation strategies and ultimately assist in the management of marine protected areas.     

Effectiveness of fishing gears to assess fish assemblage size structure in small lake ecosystems

Measurement of fish body‐size distributions is increasingly used as a management tool to assess fishery status. However, the effects of gear selection on observed fish size structure has not received sufficient attention. Four different gear types (experimental gill nets, fine mesh bag seine, and two different sized mesh trap nets), which are commonly employed in the study area for fisheries surveys, were used to fish in five small (< 200 ha) lakes to evaluate differential catch in terms of species composition and assemblage size distributions. Kolmogorov–Smirnov tests revealed that, out of the five lakes and six comparisons, the four gear types captured fish of statistically similar size distributions in only one instance. Non‐metric multi‐dimensional scaling followed by a multi‐response permutation procedure revealed that the species composition of fish captured by these gears also differs. These results support the notion that multiple gear types should be used to assess body‐size distributions as well as fish assemblage composition.     

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

Discarding non‐target fish from commercial fisheries is controversial and has been a persistent concern for fisheries managers globally. Discard management strategies typically begin by understanding mortality rates among discarded fish, a challenging task given the dynamic, highly context‐specific nature of fisheries. An alternative is to develop our knowledge of how stressors operate by first understanding the causes of mortality that drive this context dependence. Particularly relevant to mitigation efforts is an understanding of how fish respond to the physical factors of fishing, such as the gear itself and methods of fishing and handling the gear. We provide a synthesis of how commercial fishing methods may influence discard mortality and outline means by which capture‐induced stress and injury can be mitigated for common commercial gear types, emphasizing method variants or alternatives during capture, handling, and release that could improve survival. This synthesis identifies exhaustion and injury as the most detrimental and ubiquitous stressors experienced by discarded fish, with few options for mitigating their effects. Trawls and hanging net fisheries are identified as the most harmful gears for by‐catch, characterized by high stress regardless of method variants and limited options for mitigation. Irrespective of gear type and type of stressor, minimizing durations of capture and handling and encouragement of good handling behaviour (e.g., during landing and sorting) will reduce the magnitude of stress and injury in fish, and ultimately increase survival.     

杭州湾南岸滩涂贝类养殖环境中微生物数量分布及其类群

研究了杭州湾南岸慈溪滩涂贝类养殖区的微生物在水平、垂直及季节变化的分布规律。结果表明:3个采样区的异养细菌的数量变动在1.62×103~6.62×105cfu.g-1之间,平均值为4.28×104cfu.g-1,细菌数量在春季和夏季的数量偏低,10月份异养细菌的数量开始上升,并于11月份达到最高,表层高于底层;其中以革兰氏阳性菌比例最高,为主要的优势种,具有陆源性特点。各站位反硝化细菌、氨化细菌和硫酸还原菌的检出率均为100%,都维持在一个较高的水平,整体上数量具有表层高于底层的特点,3种微生物在数量上的季节演替与异养细菌具有类似的结果,均为10-11月达到最大。