我国海水网箱养殖的现状、存在的问题及今后课题

报道了中国海水网箱养殖技术的发展现状，介绍了网箱结构类型，以及主要养殖品种和深海抗风浪网箱养殖技术特点，分析了海水网箱养殖业存在的问题，提出了网箱养殖业可持续发展应当开展的研究课题。     

名贵水产网箱养殖技术：（一）名贵水产网箱养殖的概况与原理

１名贵水产网箱养殖的概况名贵水产网箱养殖是当前国内外普遍兴起的一项养殖新技术，它是在常规网箱养鱼的基础上演变而来的一种新兴的科学养鱼方法。追溯网箱养鱼的历史，其发源地在柬埔寨的湄公河。２０世纪３０年代传到泰国，日本在同一时期开始，目前，其网箱养鱼工艺...     

池塘网箱养殖水体溶解氧的测定分析

探讨了池塘网箱养殖水体网箱区，非网箱及网箱内外溶解氧的变化特点。在第ｄ上午１０：００到午夜０２：００，非网箱区溶解氧一般高于网箱区溶解氧２－３ｍｇ／Ｌ，网箱养殖区内，网箱内溶氧量常高于网箱外；各网箱内溶解氧因养殖品种不同存在一定差异。     

小体积高密度网箱养殖技术简介

１９９１年，小体积高密度网箱养殖技术传入我国，１９９６年这类网箱养殖体积达到５０ ０００ ｍ~３，产量达７ ０００ ｔ。为了探索小体积高密度网箱养鱼技术在海水中的养殖效果，深圳市龙岗区水产研究所承担了美国大豆协会小网箱养殖金媚的试验项目，笔者有机会参加了这项工     

我国深水网箱养殖技术及发展展望（上）

深水抗风浪网箱代表着海水网箱养殖的发展方向,是国家今后重点支持的先进的海水养殖方式。为此本刊特邀国内著名的深水网箱养殖专家徐君卓教授就我国深水网箱的发展现状、养殖技术、挪威深水网箱发展情况等内容作一介绍,刊出后收到了很好的效果,很多读者纷纷来电、来函询问深水网箱的有关问题,并希望我刊能多刊登这方面的文章。我刊又邀中国水产科学研究院南海水产研究所深水网箱课题组负责人郭根喜研究员等专家重点就南海区深水网箱发展概况、深水网箱养殖适宜的养殖水域条件、深水网箱养殖技术及今后的发展前景作一系统介绍。     

网箱中的航母——大型抗风浪可移动网箱

目前网箱养殖业在国内正在兴起，网箱的形式也各有特色，但主要以静态网箱为主。随着对网箱养殖的管理、经济效益、存活率要求的不断提高。国外推出了一种新型的网箱——移动式网箱，本对这类网箱作简要介绍。     

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。     

海水网箱养殖现状及抗风浪网箱养殖的发展前景

报道了中国与广东省海水网箱养殖的现状及存在问题，介绍了深水抗风浪网箱的特点及国外深水抗风浪风猜想垢主要，描述了广东深水抗风浪网箱养殖的发展前景。     

网箱养殖黄鳝技术

网箱养殖黄鳝，即利用聚乙烯（或尼龙线）网制成适宜规格的网箱作为养殖空间，在网箱中投以人工培育的鳝种，进行饲养管理，最终生产出商品黄鳝。１９９８年，湖南益阳绿源黄鳝繁养场利用网箱养殖黄鳝水面２７００，年获利达２８．７万元。其中１口面积为２０的网箱，６月...     

网箱养殖彭泽鲫鱼技术指导

网箱养殖彭泽鲫鱼技术指导谢岳成（湖北省监利县水产局）１．选择养殖水域网箱养殖彭泽鲫与网箱养殖鲤鱼、罗非鱼一样，网箱养殖彭泽鲫鱼所选择的养殖水域非常广泛，包括河流、湖泊。水库、工厂温流水等环境。几种水域环境用网箱养殖彭泽鲫鱼唯一不同点是放养最适密度不一...     

Grow-out of juvenile seahorse Hippocampus kuda (Bleeker; Teleostei: Syngnathidae) in illuminated sea cages

This paper examines the feasibility of rearing 10–15-day- and 0.7–1.5-month-old seahorse Hippocampus kuda in illuminated sea cages to continue existing hatchery protocols to mass produce H. kuda for trade and enhance depleted wild stocks in their natural habitats. Thawed Acetes (a planktonic crustacean abundant in inshore seas) was fed to juvenile seahorses in lighted and unlighted sea cages while one group in lighted cages was not fed Acetes . After 10–12 weeks of rearing, both mean body weight and stretch height increased in all treatment groups, with lighted cage-reared seahorses fed Acetes being heavier (2 g) and longer (8 cm) than the other two treatment groups. Although instantaneous growth rates declined during the rearing period, these were generally higher among Acetes -fed seahorses in lighted cages (0.02–0.07) compared with those in the unlighted cages with Acetes and lighted cages without Acetes feeding. Mean survivorship in all groups ranged from 9% to 74% after the trials, but mean survivorship of juveniles in lighted cages with Acetes feeding (9–74%) was consistently lower than the two treatment groups as a likely result of crustacean and piscine predators being attracted by light and the odour of leftover Acetes in the lighted cages. These results demonstrate that light-attracted zooplankton prey supplemented by Acetes feeding may provide essential nutrients for the growth of H. kuda juveniles in illuminated sea cages. With further improvement in the grow-out protocol, it may provide a possible alternative livelihood to seahorse fishers and sufficient seed to re-populate depleted wild stocks of H. kuda .     

Effects of water flow velocity and fish culture on net biofouling in fish cages

The effects of water flow, fish feed and cage position on net biofouling was examined in a floating cage fish farm. Fouling of 16 mm mesh net panels suspended inside and outside net cages and exposed to different treatments were monitored weekly until net apertures were completely occluded by the fouling organisms (8 weeks). Results indicate a dramatic reduction in water flow velocity throughout the fish farm due to the cage units themselves and net biofouling. The reduced water flow (<10 cm s^?1) inside net cages promoted rapid net biofouling, while rapid water flow outside the net cages (>25 cm s^?1) kept the net fouling organisms at bay. Although fish rearing in net cages with inputs of commercial pellet feed increased sessile biofouling (222% higher than outside the net cages) and non‐sessile biofouling (570% higher), the type of fish feed used did not significantly affect biofouling development. The study recommends that the geometry of serially arranged net cages, as commonly deployed in tropical tidal estuaries, be reconfigured to improve flow through in order to minimize the impact of fouling.     

Swimming nets have positive effects on populations of the endangered White's seahorse Hippocampus whitei

1. Habitat degradation and destruction arising from rapidly increasing urbanization represents one of the most significant threats to biodiversity. Human populations are continuing to increase around coastal regions, and as marine habitats are displaced by artificial structures it is important to understand how marine species may be impacted by these changes in habitat availability. The endangered seahorse Hippocampus whitei has been observed inhabiting protective swimming nets in Sydney Harbour, Sydney, Australia, even in the presence of natural habitats.
2. This study tested whether the presence of a swimming net results in increased seahorse numbers at sites around Sydney Harbour, or whether seahorses are attracted away from natural habitats. Density surveys and mark–recapture population estimates were done at sites with pre-existing swimming nets and compared to control sites where only natural habitat was present. A manipulative experiment was conducted in which panels of swimming net material were installed at two sites in Sydney Harbour, with comparisons to control sites over a period of 14 months (April 2018 to June 2019) to test whether the installation of swimming nets would affect seahorses on surrounding natural habitat or increase site abundance.
3. The pre-existing and installed swimming nets were found to support greater densities of H. whitei as well as some increases in site-scale abundance, with no effects on seahorse density on natural habitats. It is likely that increased seahorse production is occurring on the nets, with no evidence that seahorses are being attracted away from natural habitat; however, effects may vary across survey occasions and sites. Furthermore, swimming nets may serve as a useful replacement habitat in locations where natural habitat has become sparse or absent.

     

团头鲂网箱养殖研究

在水库进行了网箱养殖团头鲂试验，采取网箱配套养殖鱼种和成鱼，自己设计饵料配方、合理投喂和防治鱼措施，１５只网箱总面积３７５ｍ＾２，共产商品鱼２３５０５ｋｇ，平无尾重４５１ｇ，盈利６．６３５万元，折合亩净产３５６１６ｋｇ，亩盈利１１．８万元。     

HDPE圆形重力式网箱受力变形特性的数值模拟

该研究旨在综合探讨不同网箱周长、浮管管径、网衣高度及网目大小对整体网箱受力变形的影响,为网箱的科学合理选型提供数据参考。设定的网箱周长40—80m,浮管管径250～630mm,网衣高度6～20m,网目大小45～115mm。通过数值模拟方法对4种规格高密度聚乙烯圆形网箱在不同组合条件下网箱锚绳受力、波流力以及容积损失率进行了数值计算。结果表明,大规格网箱的锚绳受力、波流力更大,容积损失率更小,锚绳数量的增加可以大大降低锚绳受力。相比浮管管径,网衣高度和网目大小对网箱受力变形的影响更显著。整体网箱的受力变形随着网衣高度的增加而增大,随网目的增大而减小。     

Extension of nursery culture of Scylla serrata (Forsskål) juveniles in net cages and ponds

To address the preference of mud crab farmers for larger size Scylla serrata juveniles (5.0–10 g body weight or BW; 3.0–5.0 cm internal carapace width or ICW), a study was conducted to compare the growth and survival of crab juveniles (2.0–5.0 g BW; 1.0–3.0 cm ICW) produced a month after stocking of megalopae in net cages when reared further in net cages installed in earthen ponds or when stocked directly in earthen ponds. In a 3 × 2 factorial experiment, three stocking densities (1, 3 and 5 ind m⁻²), two types of rearing units (net cages or earthen pond) were used. Megalopae were grown to juvenile stage for 30 days in net cages set inside a 4000 m² brackishwater pond and fed brown mussel (Modiolus metcalfei). Crab juveniles were then transferred to either net cages (mesh size of 1.0 mm) or earthen ponds at three stocking densities. After 1 month, no interaction between stocking density and rearing unit was detected so data were pooled for each stocking density and rearing unit. There were no significant differences in the growth or survival rate of crab juveniles across stocking density treatments. Regardless of stocking density, survival in net cages was higher (77.11±6.62%) than in ponds (40.41±3.59%). Growth, however, was significantly higher for crab juveniles reared in earthen ponds. The range of mean BW of 10.5–16.0 g and an ICW of 3.78–4.33 cm obtained are within the size range preferred by mud crab operators for stocking grow‐out ponds.     

罗氏沼虾大规模家系构建与培育技术研究

为建立罗氏沼虾育种项目,2006年利用罗氏沼虾3个群体,通过巢式交配设计,实现了大规模构建罗氏沼虾父系半同胞家系。实验中,每箱放置亲虾1雄5雌,按交配设计共布置100个交尾网箱;通过对培育条件及幼体数量的标准化,使每个家系在幼体培育的各个阶段的条件尽量保持一致,减少由于条件不一致造成的家系间的环境偏差。结果显示,500尾雌虾抱卵虾为271尾,亲虾抱卵率平均为54.2%,且每个网箱出现两尾以上抱卵虾的网箱数为92个,占全部网箱数的92%;通过标准化培育,最终建立了123个家系,其中含有父系半同胞家系37个。本试验结果为建立罗氏沼虾全同胞和半同胞家系提供了依据。     

High incidence of death due to collision of hatchery-reared Pacific bluefin tuna Thunnus orientalis juveniles in sea cages, as revealed by head and spinal injuries

High mortality of hatchery-reared Pacific bluefin tuna (PBT) juveniles is frequently observed in sea cages after transfer from indoor tanks, and is likely due to collisions of the fish with the net wall of the sea cages. Because collisions frequently cause bone injuries due to physical impact, such injuries can be considered an index of obvious collisions. In the present study, bone injuries of dead juveniles were investigated in order to examine the prevalence of net collision as a cause of death among hatchery-reared PBT juveniles in sea cages. Juvenile PBT were reared in sea cages for 90 days after transfer, and dead fish were collected and examined by the clearing and staining method or by dissection to detect injury to the vertebral column and parasphenoid. The prevalence of injuries to the vertebral column and parasphenoid until day 30 after transfer was low (0.0–12.0 %) when the fish were 5.5–15.2 cm in total length (TL). However, it drastically increased to 17.8–78.0 % for fish 21.0–39.2 cm TL from day 31 onward after transfer. These results suggest that the mortalities of juvenile PBT larger than 20 cm TL in cages were induced by net collisions.     

Striking a balance between retaining populations of protected seahorses and maintaining swimming nets

• 1. The fish family Syngnathidae (seahorses, pipefish, pipehorses and seadragons) is fully protected in New South Wales, Australia, but in some countries certain species are threatened by unsustainable collecting, capture as incidental bycatch, and habitat degradation.
• 2. Within Sydney Harbour, two species of seahorses (Hippocampus abdominalis and Hippocampus whitei) have been found to colonize artificial structures such as jetty pylons and protective netted swimming enclosures. These protective nets are subject to fouling from epibiotic growth (algae, ascidians, bryozoans, etc.) and rubbish, which causes the nets to collapse from the additional weight. Local authorities employ diving contractors on an ad hoc basis to remove the epibiota from nets.
• 3. Surveys showed a significant decline in the numbers of both seahorse species at one site following the replacement of a net, and recovery of the H. whitei population took more than 15 months.
• 4. A manipulative experiment tested the importance of epibiotic growth for seahorses. H. whitei, tagged with individual marks, were allocated to sections of a net that had undergone different cleaning procedures. Seahorse size, position on the net and total population abundance were recorded every 2 weeks over a 3 month period. It was demonstrated that seahorses have a significant positive association with epibiotic growth and proximity to the sea floor. Seahorse populations also showed seasonal variation in abundance with increased numbers on the net during the breeding season (spring–summer).
• 5. This project has led to the development of best practice net cleaning procedures for local authorities in Sydney Harbour to manage growth on the nets while minimizing impacts on seahorse populations. Copyright © 2009 John Wiley & Sons, Ltd.

     

Technological solutions and operational measures to prevent escapes of Atlantic cod (Gadus morhua) from sea cages

Escapes of cod (Gadus morhua) from sea cages represent an economic problem for farmers and a potential environmental problem. We estimate that 0–6% of cod held in sea‐cage farms in Norway were reported to have escaped each year from 2000 to 2005, which is a high proportion compared with salmon. We interviewed employees at 19 coastal sea‐cage cod farms in Norway to investigate both how and why cultured cod escape and to document cage handling and management strategies that were effective in minimizing escapes. Based on the interviews, we describe five working hypotheses that may explain why a greater proportion of cod than salmon escape: (1) cod are more willing to escape than salmon; (2) cod bite the net cage and create wear and tear; (3) net cages have insufficient technical standards for cod culture; (4) cod are placed in sea cages at considerably smaller sizes than salmon; and (5) cod are more popular feed for predators. Preliminary testing of the hypothesis that cod bite netting and create holes was done by placing pre‐damaged net panels with cut twines and control panels inside sea cages. Holes in the pre‐damaged net panels increased in size over a period of 3 months. The type of damage indicated that biting of netting twines was the likely cause.