深水抗风浪网箱养殖成功经验简介

胶南市是青岛市西海岸的一座新兴海滨城市,海岸线长131公里,20米以上浅海水域约500平方公里,滩涂面积55平方公里。2004年全市水产品总产量30.4万吨,实现水产品现价收入30.6亿元。水产养殖面积达15.5万亩。近年来,充分发挥资源优势,加快发展高效渔业,特别是深水抗风浪网箱养鱼取     

深水抗风浪网箱养殖:巨型网箱令人叹为观止

在“海棠”台风来临前，一组4个巨型深海养殖网箱被放入了大亚湾三门岛海域中，这是广东省海洋与渔业部门开辟首个深水抗风浪网箱养殖示范基地的第一次试验。4个深水抗风浪网箱面积706平方米，养殖水体5650立方米。这是我国目前最先进的养殖方式。     

泉州市大型抗风浪深水网箱养殖规划

2003年3、4月对泉州市沿海海区进行水深、底质、海流等项目的观测，并根据2000—2001年全省各主要养殖港湾海洋物理、化学和生物等多学科的综合调查资料及其它相关历史资料，结合目前国内大型深水抗风浪网箱生产厂家的技术指标，初步确定了泉州市几个适合大型抗风浪深水网箱养殖的海域，并根据各海域的环境综合指标，建议近期将深沪湾试验基地的网箱移至围头湾，同时进行小规模养殖生产。通过试验生产，努力研究开发，不断总结经验，逐步提高大型深水抗风浪网箱的抗风浪能力及对各种不同海域条件的适应能力。     

大黄鱼深水抗风浪网箱养殖技术

大黄鱼深水网箱养殖目前还较为少见,由于养殖过于密集造成水质富营养化,每年病害频发且品质下降,针对该现象,我们于2010年4-12月对大黄鱼的抗风浪网箱养殖进行试验,现将养殖结果介绍如下:一、材料和方法1.养殖海区选择在沙埕港虎头鼻海区(此海域与浙江坛紫菜养殖之乡沿浦港相毗邻),水质条件好,水流畅通,海域常年水温在10.5～30℃,海水     

深水抗风浪网箱养殖许氏平鲉技术研究

为探讨在连云港地区采用深水抗风浪网箱养殖许氏平鲉的可行性,在海州湾中部人工鱼礁区进行了网箱养殖许氏平鲉试验.结果表明,在10.1、19.7 kg/m2两种密度条件下,许氏平鲉的成活率分别为84.67％和79.70％,平均体质量分别增长了43.0％和50.3％.在自然条件下采用深水抗风浪网箱养殖许氏平鲉能够顺利越冬,越冬期间体质量平均增加了35 g/尾,增长率为16.1％.     

广东省深水抗风浪网箱的发展情况和前景

我省海水鱼类网箱养殖始于20世纪80年代初，进入90年代以来，我省海水网箱养殖发展迅猛，2002年我省海水网箱数量约15万只，居全国第二位，产量达5万t左右，已成为推动各地海洋渔业经济发展的重要增长点。但在海水网箱养殖迅猛发展的同时也暴露出诸多问题：(1)养殖密度过大，远远超过了海区养     

我国大型深水抗风浪网箱养殖产业化初探

在中日、中韩渔业协定的实施以及海水渔业资源严重衰退的情况下,为使渔业经济可持续发展．大型深水抗风浪网箱制作技术已列为国家“863”计划,并取得了一些初步成果。要使这一技术和大型深水抗风浪网箱养殖业得到迅速普及和规模发展,必须解决一些相互关联的技术问题,并采用恰当的产业经营模式。大型深水抗风浪网箱养殖的产业链式特征,决定了采用产业化股份制经营模式是推进其快速持续发展的有效途径。     

巨型深水抗风浪网箱养殖令人叹为观止

日前，“海棠”台风来临前，一组4个巨型深海养殖网箱被放入了大亚湾三门岛海域中。4个深水抗风浪网箱面积760米^2，养殖水体5650米^3。这是我国目前最先进的养殖方式。     

外海抗风浪网箱系统

本文阐述国内港湾近岸网箱养殖存在许多问题，因此有必要开展外海抗风浪网箱系统研究，拓展新的养殖空间发展外海网箱养殖业，本文还介绍了网箱基本结构、系统组成。     

高海况漂浮物打捞网具的研究试验

为在高海况下安全打捞落水人员和重要的漂浮物,设计了一种打捞网具。为此研究了打捞过程中船舶行进速度、网口高度、打捞物体吃水深度等参数对打捞网性能影响;通过网具模型试验,模拟网具打捞作业,测试网具在打捞体进网前后力的变化,分析了打捞物体吃水深度与进网匹配性、进网的拖网速度以及网具受到的最大撞击力等。结果显示,试验用打捞体的进网条件受其吃水深度和网具拖速的影响较大。在打捞体吃水深度一定时,打捞体可在拖速≥2.5 kn时顺利进入网内;但当拖速过大,网口垂直扩张系数越小,不利于进网。试验范围内的最大撞击力随着拖速的提高而增大,最大值为27.84 k N。研究表明,网具最大撞击力的参数值对网线材料的选择与强度设计、网具支撑拦截臂架的结构强度计算具有指导意义。     

Effects of waves and currents on gravity-type cages in the open sea

The effects of waves with a uniform current on marine aquaculture gravity-type cages were analyzed using a numerical model previously validated by physical model tests. The present analysis employs a numerical algorithm to study the dynamic behaviors of the net-cage system when impinged upon by surface waves from various angles over a uniform current. The maximum tension of the mooring lines and the minimum volume reduction coefficients of the rearing system were analyzed. We found that the current-induced effects on the net-cage system were more important than those due to waves only. We conclude that farming sites should not be situated in areas where the current speed exceeds 1 m/s, unless technological devices are available to overcome serious net-cage volume deformation. Furthermore, we recommend that, whenever possible, the combined effects of various oblique waves and currents be carefully examined before a system is installed. Finally, the ideal range of water depth for net-cage implementation in the open sea is between 30 and 50 m.     

福建沿海张网作业捕捞能力的计算分析

根据2002年福建沿海张网作业的生产调查及全省渔业统计,应用数据包络分析(DEA)法,分析福建沿海6个地级市和4个县市张网作业的捕捞能力及其影响因素,并与单位捕捞努力量渔获量(CPUE)法进行比较。结果表明,2000年和2002年,福建沿海张网作业"能力利用度"的变化范围分别为5 2%～100%和7 3%～100%,平均为67 2%和80 9%。各地市间张网作业的"能力利用度"有极显著差异(P<0 01),对给出的投入要素的利用未达到充分发挥其应有产出能力的水平,存在张网作业船数和网具数量的投入过多、渔船功率和吨位的投入偏大的问题。调查36个捕捞单位的"能力利用度"变化范围为46 4%～100%,平均77 4%。4个县市不同生产水域间张网作业"能力利用度"的差异极显著(P<0 01),捕捞单位间的"能力利用度"有显著差异(P<0 05)。近海有翼张网的平均"能力利用度"高于沿岸无翼张网的平均"能力利用度";张网捕捞单位投入的功率、吨位、网具数量、渔船数和作业天数,对其捕捞能力的发挥有比较重要的影响。跨生产水域比较各捕捞单位投入的网具规格和船员数对其"捕捞能力"有一定的影响。CPUE法仅适用于单一或两个投入因子的计量,不足以充分反映张网作业的实际捕捞能力;DEA法则擅长多种投入要素的生产决策,提供各种约束条件的最优选择途径,可以有效获取比     

Examination of net volume reduction of gravity-type open-net fish cages under sea currents

Owing to heavy criticisms of nearshore fish farming for causing environmental pollution and encroaching on sea space used for shipping, boating, recreational sea activities and marine eco-tourism, offshore fish farming has now being seriously considered. Moreover an offshore site provides more pristine water and greater space for increased fish production. However, offshore fish farming poses challenges such as a more energetic sea environment. A higher sea current can lead to large deformation of fish net and hence a net volume reduction which compromises fish welfare. With the view to identifying the effects of various important parameters on net volume reduction of a gravity-type open-net fish cage, this paper adopts a mass-spring model for the dynamic analysis of current-induced net deformations of cylindrical fish nets with discrete weights hanging at the bottom edge of the nets. In this model, the net mesh comprises knot nodes and bar nodes connected by tension-only massless springs. The spring stiffness is determined from the net bar diameters and material properties. The current-induced loads are applied to each node and calculated based on Morrison’s equation. The governing equation system for nodal motions can be established according to Newton’s second law, and solved by using the Runge-Kutta method for the real-time net deformations. The effects of net string reinforcements, weight distributions and net shapes on the net volume reduction are studied with the view to shed insights into how one may improve fish cage designs to effectively mitigate net deformation under high sea current speeds in offshore fish farming sites.     

Optimization of the stocking parameters for mud spiny lobster Panulirus polyphagus (Herbst, 1793) capture‐based aquaculture in tropical open sea floating net cages

Mud spiny lobsters, Panulirus polyphagus (Herbst, 1793), were reared at four different stocking sizes and stocking densities in open sea cages to evaluate their effects on growth performance. To evaluate the effect of stocking size on the growth performance, the lobsters were segregated into four different treatment groups according to size and were stocked at a density of 300 animals per cage. To evaluate the effect of stocking density on the growth performance, lobsters of 81–100 g were stocked in four different stocking densities, i.e. 16/m², 24/m², 32/m² and 40/m². The results showed that the growth rate of (60–80 g) size group, was significantly higher compared to the size groups, i.e. 101–120 g and 121–140 g comprising of larger individuals. The final body weight, though significantly higher in 81–100 g as compared to 60–80 g, the growth performance (i.e. weight gain percentage (WG %) and specific growth rate (SGR)) were not significantly different. The density‐dependent influence on growth performance was evident in this study. The WG % and SGR during 90 days’ culture period was significantly higher in 24/m² compared to other groups. This study provides crucial information about the appropriate stocking density and stocking size of lobsters at the field level, which would help to promote sustainable lobster cage farming by maximizing the production potential of the system.     

舟山桁杆拖网渔具渔法分析

桁杆拖虾是20世纪80年代以后迅速发展起来的新兴捕捞作业方式,主要用于开发沿海渔场虾类资源.桁杆拖虾作业方式引进舟山后,迅速成为舟山海洋捕捞业的主要作业方式之一.2013年5-11月通过实地调查,对舟山地区桁杆拖网的捕捞对象、渔具结构、操作方法等进行了分析研究,指出当前舟山桁杆拖虾作业中存在的问题:底杂鱼及蟹类等副渔获物所占比例大,数量和重量占总渔获12.12％和66.58％;使用电脉冲惊虾仪等违法作业仍然存在;网目规格普遍小于国家标准.根据上述问题提出:加装分隔网片,改善网目结构,加大执法力度等相应建议.     

The cause of death of juvenile Pacific bluefin tuna (Thunnus orientalis) reared in sea net cages

Although the survival rate of juvenile Pacific bluefin tuna Thunnus orientalis (PBT) during 30 days after stocking in sea net cages has been as low as approximately 50%, the reason for this high mortality is not clear. The dead fish were collected and counted during 30 days after stocking in a sea net cage, and the growth performance, stomach contents, and bone injury were investigated. Nearly half (47.9%) had died within the first 4 days. The total length and body weight of the dead fish were significantly smaller than those of the live fish, and the weight of the dead fish did not increase during the first 7 days. Approximately one-third of the dead fish (21.9–42.9% per day) had ingested inorganic matter such as wood or Styrofoam waste during the first 7 days, and 25.0–45.0% of the dead fish sampled per day showed poor growth. The daily ingestion rate of inorganic matter decreased dramatically from the eighth day, when the daily mortality rate decreased. The percentage of dead fish with bone injuries due to collision or contact was low (less than 15%). These results suggest that one of the causes of high mortality during several days after stocking in a sea cage was accidental ingestion of inorganic matter by juvenile PBT. Improvement in feeding method can increase the survival rate of juveniles in sea net cages.     

Spontaneous maturation and spawning of milkfish in floating net cages

Milkfish (Chanos chanos Forsskal) reared from wild-caught fry and from hatchery-bred fry matured at 3.5–5.5 years (2.3–4.9 kg). Maturation and spawning of the hatcherybred fish marks the first time the milkfish life-cycle has been completed in captivity.Milkfish at various stages of gonadal development were obtained in July–October 1980 and March–June 1981 derived from wild-caught fry, and in February–June 1983 from the hatchery-bred fish. The fish were held in floating net cages 9 m and 10 m diameter by 3 m deep, located in 7 m deep water off Igang, Guimaras Island, Philippines. Annual ranges of temperature and salinity were 25–33°C and 25–38 ppt, respectively. The fish were fed commercial feed pellet (42% protein) at 1.5–2% of body weight twice daily.Sexual maturation occurred during the natural breeding season of wild milkfish in the nearby waters. Gonadosomatic index (GSI) of mature males was 0.32–3.95 (wild-caught, 0.32–3.95; hatchery-bred, 1.71–3.85). For mature females it was 1.24–8.12 (wildcaught, 1.56–7.62; hatchery-bred, 1.24–8.12). Two spawnings were recorded in August 1980 and eight in May–July 1981 from the broodstock derived from wild-caught fry, with 342–6293 eggs collected from each spawning, while 14 spawnings were observed in May–June 1983 from the hatchery-bred fish, with 770–114 000 eggs collected. The time of spawning was between 23.00 and 02.00 h. Fertilization rate was 55–99% for the broodstock from wild-caught fry and 47–100% for the hatchery-bred fish. Hatch rate varied from 9 to 80%.Factors affecting spontaneous maturation, spawning and rematuration are discussed. Although slight improvements in egg collection were obtained, further innovations in egg collecting techniques will have to be developed. The results indicate the potential for hatchery production of milkfish fry from captive broodstock and for restocking of waters deprived of naturally occurring fry.     

Numerical investigation of the hydrodynamic behaviors of multiple net cages in waves

Large fish farms that include multiple-cages are becoming common in the aquaculture industry. Selecting an appropriate mooring structure and arrangement of cages is necessary to avoid fish cage and mooring grid system failures. A numerical model based on the lumped mass method and the principle of rigid body kinematics is developed to predict the hydrodynamic response of a fish cage and mooring grid system to regular waves. To validate the numerical model, a series of experiments is conducted. The numerical results of this model correspond with those obtained from experimental observations. Then, two cage arrangements are investigated, and the effect of the wave direction is analyzed. The results show that when the wave incident angle is 0°, the maximum tension forces on the anchor lines of the two cage arrangements are close to each other. There is not a significant difference between the effective fish cage volumes of the two cage arrangements. However, if one anchor line is broken, the two cage arrangements have different degrees of risk of having the cage structures swept away. When the propagation direction of the incident wave changes, the tension forces on the anchor lines also change due to different transfer load paths.     

海洋渔船捕捞安全性分析

我国渔船捕捞出险概率高达18%,是名副其实的高危行业,开展渔船安全保障工作刻不容缓。本文通过对渔船捕捞生产过程的分析,确定渔船捕捞生产的不安全因素,建立捕捞生产过程事故规律模型及渔船生产安全因素交互模型。针对渔船捕捞生产不安全因素,本文提出了提升渔船设计能力、建立渔船通讯网络、完善监管机制等解决措施。