对辽宁省淡水渔具渔法今后发展的看法

近十余年来，辽宁省的淡水捕捞事业有了很大的发展，各地渔业工作者不仅完善与发展了原有的渔具渔法，而且还不断吸取国内外先进经验，引进和试验了不少新的渔具渔法，从而使我省淡水捕捞的渔具渔法进入了一个新阶段。纵观全省所使用的各种淡水渔具渔法，几乎包括了淡水渔具渔法的全部分。     

南海区围网渔具的技术特征及对资源的开发利用状况

围网，是我国南海区主要渔具之一。渔具种类分有：无囊围网、有囊围网、有底环围网和无底环围网，作业时配合光诱和敲吓。其中有环无囊围网。俗称“索罟”。六十年代中期，在取缔使甩鱼炮之后，光诱索罟在网具结构、渔具材料和捕捞操作等方面，发生了重大的变革，获得显著的效果，推动了灯光围网的发展。七十年代末期，由于资源波动等原因，国营渔业淘汰了机轮围网作业。     

南海区海洋渔具的改革

南海区海洋渔具有着悠久的历史。建国后，广大水产科技工作者和渔民群众对历史遗留下来的传统渔具进行了多次的改革，取得了显著的效果，大大促进了海洋渔业的发展。为了使读者了解和掌握各种渔具的变革状况，现将拖网、围网、刺网及钓具等四种主要渔具的技术改革情况分述如下：     

关于渔具分类的研究

本文指出渔具分类的重要性，同时对现有各种主要渔具分类见解进行历史地评价，并着重就“渔法”的定义进行探讨。在此基础上按渔具的渔捞原理提出新的渔具分类系统。本文建议对渔具作类——型——种三级分类，将全部渔具分成11个类：1．投刺、抄捞渔具，2．钓渔具，3．陷阱渔具，4．集捕渔具，5．掩捕渔具，6．刺网，7．敷网，8．张网，9．围网，10．旋曳网，11．拖曳渔具。免除传统的渔具分类中为某些无所归属的渔具而设置的“其他”等称谓的这一类别。     

浅谈拉钓及其经济效益

拉钓，因其钓钩上不挂鱼饵，故又名滚钩，是一种历史悠久的传统渔具之一。它在海洋捕捞中具有产品质量优、不易损害资源、能源消耗低、成本开支省、生产时间长、经济效益高等优点，而且投资省、收效快，是一种有发展前途的良好渔具。     

延绳钓渔具的捕鱼性能,选择性与鱼类保护及节能

一、引言延绳钓捕鱼是一种世界性渔法。尽管延绳钓的装配方法和作业方式各有不同,但它基本上是一种非常简单的渔具渔法。延绳钓渔具的捕鱼效果如何,取决于一系列的生物与非生物因素之间的复杂的相互影响。本文着重叙述了延绳钓渔具的主要参数最新研究结果、延绳钓渔具和拖网渔具在鱼类保护及节能方面的效果。     

罾轮捕池养罗非鱼技术

人们习惯利用刺网或大型抄网轮捕池塘养殖的罗非鱼。虽然两者之捕捞效果均不错，但是，刺捕摘鱼相当麻烦费时，容易伤及其他养殖鱼类，而且渔获物不易暂养；抄捕则嫌网产不高，单位渔获物耗时多。为此，笔者把江河小型渔具——罾应用于池塘轮捕罗非鱼，收到了较好的效果。现总结如下。     

渔具、渔具材料标准化之路

渔具、渔具材料专业标准化工作起步于六十年代，全面展开工作在七十年代末期。经过二十多年的发展，渔具、渔具材料标准化工作取得了可喜的进展。首先是建立了必要的机构。为适应渔具、渔具材料标准化工作发展的需要，于1979年成立了渔具、渔具材料专业标准化技术归口单位，1991年成立了全国水产标准化技术委员会第一届渔具分技术委员会和渔具材料分技术委员会，1997年过舒了换届。目前，现有委员33人，其中，也具分技委18人、渔具材料15人。这两支队伍是开展渔具、也具材料标准化工作一支主要的骨干队伍。两个分技委秘书处均挂靠在中国水产…     

刺网渔具选择性研究进展

刺网选择性研究是渔具选择性研究领域中的重要部分，其对于渔业管理、资源调查和评估等都是至关重要的。本文以刺网渔具的4种渔获方式为研究基点，通过对刺网渔具选择性特点的描述，介绍各种刺网渔具选择性曲线的表示方法。根据国外多年来对刺网渔具选择性研究方法的发展进程，对当前几种常用的选择性曲线间接估算方法（SELECT模型、同时估算选择性曲线和种群资源的方法以及同时估算A类和B类曲线的方法）的原理和运用现状进行详细介绍。对间接估算法中常用的假设条件（几何相似原理、相同渔获能力等）、估算方法的缺陷和相互之间的关系以及在进行刺网渔具选择性研究时所要关注的问题等进行了讨论，为今后深入开展刺网渔具选择性研究提供参考。     

网片缝合比计算公式分析与探讨

在渔业生产中渔具种类繁多,其中网渔具不仅在数量上而且在渔获量上都占绝对优势。网渔具通常由若干不同形状、边缘网目数不相等的网片缝合而成,缝合的好坏,直接影响着网片的受力和渔获量。因此在网渔具的装配中要准确地计算网片的缝合比和缝合次数,使网片缝合均匀。     

冰冻杂鱼切块机精准自动控制技术研究

为提高渔业养殖效率,改变现有杂鱼块不平整和破碎率较高等缺点,研制了一种自动化程度较高的冰冻杂鱼切块机。采用变频调速技术,以通用串行通信接口通讯协议实现西门子PLC与MM440变频器通讯,用普通齿轮减速电机进行杂鱼切块宽度调节,用测距传感器进行精确测距,对射式光电计数器进行切块计数。通过PLC控制变频器参数,设置减速电机的运行参数,再运用PLC与上位机之间的串口通讯,实现良好的人机交互,从而完成切块机精准自动控制。性能测试结果显示,在额定电压400 V条件下,切块速度25~35块/min,可将600 mm×400 mm×80 mm的杂鱼板切成宽60~90 mm,宽度可调;空载状态下,功率0.26 k W,负载运行时的转速、功率、扭矩成正比。在指定宽度下,切块精度为±5%,切块个数准确。研究表明,该控制系统可靠,适合在沿海渔业养殖中应用推广。     

Survival and growth of larval and juvenile tench, Tinca tinca L., fed different diets under controlled conditions

Abstract. Tench, Tinca tinca L., larvae were reared under controlled conditions at water temperatures of 28°C and 31°C during a 15-day period. Feeding with exclusively live Artemia nauplii gave best results, irrespective of rearing temperature (total length 13·6mm; average weight 31 mg; survival rate 83–85%). High survival rates of 81–88% were found also in all groups fed mixed diets, whereas growth rate of tench larvae was significantly influenced by the frequency of supplemental feeding with Artemia. When applied alone, the tested carp starter feed turned out to be insufficient for rearing the larval tench.     

Night stocking facilitates nocturnal migration of hatchery-reared Atlantic salmon, Salmo salar, smolts

Abstract  Hatchery-reared salmon, Salmo salar L., smolts are generally stocked during daylight hours, but the natural migration of smolts tends to occur at night. Recapture rates and timing of migration were compared between Atlantic salmon smolts stocked during the day and during the evening. Timing of release had no significant effect on the number of smolts recaptured, but had a strong effect on nocturnal behaviour. When stocked in the evening (but not during the day) hatchery-reared smolts moved almost exclusively during the night. This study suggests that timing the release to coincide with the natural time of smolt migration may provide valuable acclimatisation and facilitate nocturnal smolt passage.     

Effect of Soluble CO2 Stabilization on the Quality of Fillets from Farmed Gilthead Sea Bream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)

ABSTRACT

Soluble gas stabilization (SGS) is a relatively recent methodology of active packaging that has been proposed to extend the shelf life of packaged fish. The aim of the present work was to study the effect of SGS applied at different extents (2 bars: 30 and 60 min) on the shelf life of sea bream and sea bass fillets packed in air during chilled storage. Quality changes were evaluated by sensory assessment, microbiological analysis (TVC), TBARs, pH value, TVB-N, and TMA-N. No significant extension of sensory shelf life was visible as a function of SGS treatment. The treatment of fillets in CO₂ at 2 bars during 60 min had a positive effect on the microbiological shelf life of both species. On the other hand, TMA-N and TVB-N showed similar changes during storage period and were not affected by the CO₂ treatment. Sea bream treated with SGS always presented higher TBARs than control samples. Nevertheless, oxidation of sea bream and in particular, of sea bass fillets, did not appear to be a significant problem during chilled storage.     

The effect of vertical and horizontal distribution on retention of sardine (Sardinops sagax) larvae in the Northern Benguela – observations and modelling

In the present study, a modelling experiment is conducted to simulate the transport of sardine (Sardinops sagax) eggs and larvae in the Northern Benguela. Based on historical and newly obtained data, different scenarios of vertical and horizontal distribution are applied and the effects on retention are discussed. The simulations showed that vertical and horizontal distribution were important for retention of sardine larvae in the Northern Benguela. By using age‐dependent data on vertical distribution, it was shown that retention of particles in the simulation was substantially enhanced compared with a scenario where particles were distributed in the offshore moving Ekman layer. Retention was lowest during October–December (when upwelling intensity is high) and highest during February–April (when upwelling intensity is somewhat lower). When different spawning areas were considered, highest retention was observed in an area near Walvis Bay. It is concluded that the behaviour of sardine larvae is adapted to the circulation system in the Northern Benguela in a way that promotes retention of the larvae in inshore nursery areas.     

Effects of temperature, wind and spawning stock biomass on recruitment of Arcto-Norwegian cod

Sea temperature has earlier been shown to have a large influence on the recruitment of Arcto-Norwegian cod, Gadus morhua. We here hypothesize that this linkage is partly due to the direct effect of temperature on larval and juvenile growth. Secondly, temperature acts as a proxy for both biotic and abiotic factors influencing recruitment. Indices of abundance of early juvenile cod (2–3 months old), 0-group cod (4–5 months old) and 3-year-old cod are analysed in more detail against the environmental temperature, wind stress components, wind-induced turbulent energy and the spawning stock biomass. To deal with autocorrelation, non-stationar-time and nun-normality, which complicate a statistical time series analysis, randomization and Box-Jenkins methods are applied. In addition to the important effect of high sea temperature during the early life stage in forming strong year classes, the results show that the spawning stock biomass is nearly as important. Also, alongshore southerly wind stress anomalies during the period of pelagic drift (from April through summer) and offshore wind stress anomalies during egg and early larval stages (in April) act favourably on recruitment. The beneficial effect of southerly wind anomalies could he linked partly to high temperature, but the flux of zooplankton-rich water from the Norwegian Sea into the feeding areas of the Barents Sea may also be increased. The favourable influence of offshore winds in April is less predominant and causal links are also less clear; possible explanations for this might be increased offshore spreading of eggs and early larvae, resulting in reduced risk of predation, and increased compensation inflow of intermediate Norwegian Sea water which, in this restricted period of time, has a high concentration of spawning copepods suitable as prey for the developing cod larvae.     

Using attraction to light to decrease cannibalism and increase fry production in guppy (Poecilia reticulata Peters) hatcheries. II: the effects of light and cannibalistic adults

Predation of newborn fish by cannibalistic adults is a major cause of fry loss in guppy breeding tanks. The efficacy of using light to attract newborn guppies into a safe area, thereby reducing the cannibalism rate, was evaluated in aquaria. The aquaria were divided using small‐mesh netting into a section with adult fish and a safe section without adults, above which a light source was installed to attract the newborns. Both, the presence of cannibalistic adults and the light, increased the number of newborns in the safe section. The effect of the cannibals was pronounced during the day, and the effect of light seemed to be more pronounced at night. The presence of light significantly decreased cannibalism rate after 30 min, but not 16 h after the introduction of newborns. When tested with cannibalistic adults that have not been fed for 5 days prior to testing, cannibalism rate was higher and the effect of light on reducing cannibalism was evident both 30 min and 16 h after the introduction of newborns. The results demonstrated the potential efficacy of using white light in reducing cannibalism and increasing fry yields in guppy hatcheries.     

A technique for electrically stimulating extrusion of spermatophores from the lobster, Homarus americanus

A technique for electrically inducing spermatophore extrusion from live lobsters (Homarus americanus) is described. When a 12-V stimulus is applied around the coxa of the fifth walking leg, a single spermatophore is extruded through the gonopore. The sperm in extruded spermatophores are morphologically normal and undergo normal acrosome reactions. The technique provides a ready source of viable sperm for in vitro studies on fertilization and for artificial insemination of freshly molted female lobsters. The spermatophore itself is a natural package for sperm storage and may be useful in the future development of lobster sperm banks.     

A predator–prey model for evaluating the spatial behaviour of fishing fleets: a case study of the red grouper Epinephelus morio fishery of Yucatan,Mexico

A predator–prey model was applied to the red grouper Epinephelus morio fishery from Yucatan, Mexico, with the aim of understanding the spatial behaviour of a mid-sized fishing fleet. The heterogeneity of the environment was considered, and different habitat quality levels were determined to address environmental differences. The behaviour of the fleet was also evaluated based on a simulation of restricted fishing areas (RFA). The model was applied utilising 5 years of information on catch and fishing effort (1973–1977). Four levels of habitat quality were defined (low, medium, high and exceptional). The total costs and revenue for a fishing expedition in the areas of exceptional habitat quality were higher due to their location farthest from the base port. The fleet was most efficient during the winter at locations in the eastern continental shelf, with the number of these areas clearly decreasing in the autumn. The model simulation of the RFA showed a total revenue reduction of 7–27 % in scenarios of RFA for adult protection. When the RFA was implemented for the protection of juvenile fish, the total revenue was not reduced, indicating that this type of RFA might be a feasible management strategy for a sustainable fishery.     

复合植被根系作用对生态岸坡稳定性的影响

生态护岸中植被根系的固土护岸效果缺乏可测性和可控性,为了确定植物根系存在对岸坡稳定性提升的量化作用,以北京市永定河莲石湖段生态岸坡为试验区,测定生态岸坡上种植典型"草-灌-乔"植被根系的形态分布及特征参数,在根系参数测定结果的基础上分析生态岸坡稳定性。通过建立根系加筋作用的力学模型,并采用基于加筋理论的极限平衡法,对岸坡浅层稳定性进行分析计算,岸坡整体稳定性采用基于强度折减原理的ABAQUS有限元模型计算法。结果表明,草本和灌木根系的加筋作用有助于提升岸坡浅层土体的粘聚力、抗剪强度和稳定性;草本和灌木根系的加筋作用对岸坡整体稳定性的影响远小于乔木根系的锚固作用,乔木种植于坡脚处对岸坡稳定性的提高最有利,岸坡安全系数可提升5.16%;乔木根系长度是岸坡整体稳定性重要的影响因素,乔木根系长度由1 m增加至3 m,生态岸坡整体稳定安全系数较素土岸坡分别增加了1.25%和14.2%,且增强速率逐渐变大;在水位变动时,生态岸坡与素土岸坡相比,其稳定安全系数最高可提升7.87%。根据岸坡浅层稳定性及整体稳定性计算结果,可以明确植被根系浅根加筋作用及深根锚固作用对岸坡土体的稳固效果,从而确定各类植被的配置方式,为生态护岸工程设计与应用提供参考。