青海地区鱼塘越冬管理措施

<正>青海地区鱼塘由于受地理气候条件的影响,溶解氧低特别是越冬期间气候寒冷,结冰厚,冰封时间长,造成鱼类越冬比较困难,给水产养殖带来不小的损失。经作者多     

鱼类越冬管理技术

讷河市地处黑龙江省西北部,冬季气候寒冷,封冰期长达5个半月,冰层厚度90cm—120cm,鱼类越冬管理难度较大。尤其是有鱼种和成鱼越冬的场户,越冬密度高,稍有不慎,疏于管理,便可造成越冬鱼类的死亡,不仅经济上遭受损失,而且直接影响到下年渔业生产的进行。因此,在整个越冬期间必须尊重科学,依靠技术,以水为基础,以氧为前提,做好管理工作,确保鱼类安全越冬。一、补水是鱼类安全越冬的基础越冬池的水应在封冰前注满,越冬期池水如能保持一定深度可不必注水。但对一些渗漏比较严重的越冬池要定期灌注新水,以保持越冬必要的水深,避免冰层凹陷。如果…     

提高鱼类越冬成活率的技术措施

黑龙江的冬季气候寒冷,封冰期长,可从每年11月中上句持续到昱年4月中下旬,对水体中高密度的越冬养殖鱼类极为不利。因此,为了确保鱼类安全越冬,提高鱼类越冬成活率,并为昱年开展渔业生产打下坚实的基础,有越冬水面的渔场和养殖户要加强鱼类越冬管理,做好预防,在鱼类越冬前和越冬期间做好如下几项技术工作：     

夏季鱼塘养殖管理措施

夏季是鱼类生长的旺盛时期，养殖管理的好坏直接影响当年的经济收益，因此，在生产管理上要做到如下工作：     

鱼类安全越冬管理措施

进入冬季以后,天气寒冷,鱼类便进入了越冬期。我国北方地区池塘养殖每年封冰期都在5个月左右,最大冰厚可达80￣100cm。由于在越冬期内鱼类很少摄食或停止摄食,新陈代谢水平降低,抗病力明显下降,所以,鱼类养殖应当加强越冬期的管理,避免由于管理不善而引起的越冬鱼类大批死亡,给养殖户造成不必要的经济损失。1越冬池的选择和清整越冬池最好选择背风向阳不渗水的池塘,面积在1hm2左右为宜,靠近水源,底泥不超过20cm,保证越冬池冰下有效水深在1.5m左右。选好的池塘,每公顷用750￣1500kg生石灰或60￣70kg的漂白粉干法彻底清塘,晾晒3￣5d。如果原塘…     

夏季鱼塘养殖管理措施

夏季是鱼类的生长旺季,此期间水温适宜,饵肥充足,鱼类摄食旺盛,是鱼类生长的黄金季节。但是,此期间气温偏高,鱼类病害等安全隐患较大。搞好此期间鱼塘的饲养管理,是实现高产高效的关键,应重点做好科学投饵、合理施肥、加强水质管理和鱼病防治等工作。     

鱼类越冬管理措施

为了减少越冬鱼类的死亡，提高经济效益，应加强三个环节的管理。首先，要加强越冬前的管理，应做好四个方面的工作：一是加强越冬前鱼病检查及营养性疾病防治。在鱼类停食前30天左右，对计划越冬的鱼类进行检查，重点对鳃、肝、胰脏和肠道等内脏器官进行检查。根据鱼病检查结果，除进行常规的鱼病防治外．要采取措施，抓住鱼类停食前的摄食时机，强化培育，以增强鱼体肥满度，提高鱼体的抗寒能力。二是越冬池的选择与消毒：①越冬池池底应平坦，淤泥不超过20厘米，土质为保水力强的粘土或壤土：②越冬用水为井水或湖库水，原池越冬要换掉1／2老水；③对越冬池水在放鱼前进行消毒，灭菌杀虫。     

冬季越冬池缺氧补救的措施

我国北方地区冬季气候寒冷，封冰期长达100天以上，最大冰厚可达80-100cm，保证鱼类安全越冬是北方地区渔业生产的重要环节。鱼类越冬池常因缺氧而造成鱼类大批死亡，所以，越冬池溶解氧的测定和增氧的方法是冬季安全生产的关键。鱼类越冬池溶氧的测定和增氧的方法是：     

养殖鱼类安全越冬措施

在冬季,除大型水库、江河、较深的湖泊很少发生越冬死鱼外,一些中小型水域和池塘常常发生不同程度的死鱼现象,据统计,历年鱼类越冬死亡率高达20%以上,因此,鱼类安全越冬问题,是水产养殖业一个重要问题。实践证明要使鱼类安全越冬,必须掌握以下技术措施。     

《中国水产》“实用技术”栏目启示

<正>为了在新的一年里有效地改进本刊"实用技术"栏目,更好地为读者服务,"实用技术"栏目现征求读者建议。您希望在这个栏目看到什么内容、涉及什么品种、需要哪方面技术及在生产实际中需要解     

新疆渭干河土著鱼类

渭干河流域的土著鱼类曾有过零星报道，李思忠记有塔里木弓鱼，叶尔羌高原鳅和斯氏高原鳅；朱松泉，武云飞等记录有长身高原鳅和叶尔羌高原鳅。我们于2003-2005年进行渭干河鱼类的采集，计有裂腹鱼亚科鱼类6种，高原鳅3种，共9种土著鱼类，对其鱼类组成特点进行探讨。     

青海省黄河珍稀濒危鱼类及保护对策

青海黄河土著鱼类有22种,有的种类正处在兴盛时期,数量很多,具有很高的经济价值;有的种群极盛期已经过去或本来种群数量就不大,目前已成为稀有种类,在渔业生产上意义不大;有的数量虽然稀少,但有潜在的经济价值或生物学上具有特殊的意义,亟待采取保护或增殖措施,以维持种群的繁衍。当前保护和拯救黄河上游濒危鱼类的任务十分紧迫。在调查、收集和分析致危成因的基础上提出相应措施。     

常规鱼类安全越冬管理须知

一、越冬大量发病、死鱼原因分析鱼种或商品鱼待价存塘越冬，由于管理措施不当等诸多不利因素，有一些地区出现越冬鱼类大量发病、甚至死鱼现象。其原因不一，大致可归纳如下：１鱼体体质差。鱼类在越冬过程中，体质消耗很大。瘦弱的鱼体内积蓄的营养不足，难以维持整个越冬期间需要，到越冬后期，鱼类就会因体质消耗殆尽而死亡。另外，体质差的鱼抵抗疾病和不良环境的能力差，染病机会增加。２缺氧。越冬水体缺氧是造成越冬鱼类死亡的主要原因。１水体清瘦、缺肥，池中浮游植物数量少，光合作用所产生的氧不够消耗；２水底淤泥太厚，水…     

强化渔政管理挽救濒危鱼类

伊犁河是国际河流,是我国北方淡水鱼类原种、良种收集、选育、推广的重要基因库之一。裸腹鲟、银色弓鱼、伊犁弓鱼、短头鲃、新疆裸重唇鱼、斑重唇鱼已列入自治区水生野生动物保护名录,裸腹鲟是我国8种鲟鱼之一,国家二级保护水生野生动物,属于珍稀鱼类。简述了伊犁河渔政管理的重要意义,分析了渔政管理中存在的问题,提出了对策与建议。     

Assessing conservation priorities of endemic freshwater fishes in the Tropical Andes region

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Trap mesh selectivity and the management of reef fishes

The regulation of mesh size has frequently been proposed as a management measure for fish traps, the predominant gear used by the reef fish fisheries in the Caribbean. Studies on trap mesh selectivity show that mesh size is a determinant of catch rates and the size at which fish recruit to fish traps. Mesh size also affects the species composition in fish traps, probably through size selectivity. Other factors also affect catch rates, and the fish size and species composition in traps, for example, soak time, trap design, trap size, species body shape. Given the variety of growth rates and maturity schedules of reef fish commonly taken in fish traps in the Caribbean, no single mesh size will optimise the yield or protect against recruitment overfishing for the entire range of exploited species. Preliminary data suggest that the fishing power of traps may decrease with increased mesh size. This would reduce the effective fishing effort and thus mortality on fully recruited size classes. Studies indicate that the mesh sizes currently in use in most Caribbean countries are too small, and that a minimum mesh size of at least 3.8–5.1 cm would be required to optimise yields for local consumption. Comparative fishing experiments indicate that an increase in mesh size in areas of high fishing mortality typically results in a reduction in catch per trap. Thus increasing trap mesh size can be expected to result in short‐term loss in revenue for fishers. However, no studies have examined the times that would be required for catches to return to the levels prevailing before the increase of mesh size, and thereafter, for fishers to recover the losses incurred during the transition period. To provide managers with an estimate of the impacts that mesh‐size regulation could have on fishers, the recovery time of catches and the financial recovery times for fishers should be modelled for a hypothetical assemblage of 10–15 reef fishes using available information. These studies would enable managers to plan for the implementation of mesh‐size increases and to communicate the potential benefits to fishers in quantitative terms.     

Horizontal and vertical distribution patterns of larval myctophid fishes in the Kuroshio Current region

The horizontal and vertical distribution of myctophid fish larvae is described based on discrete depth sampling from the surface down to 200 m at seven stations on a transect crossing the Kuroshio Current on 6–9 July 1977. A total of 7819 larvae was collected. Myctophid larvae accounted for 72% of the total fish larvae and included 18 species or types belonging to 12 genera. Based on horizontal distribution patterns these species (or types) were categorized into three groups, i.e. Kuroshio-axis group ( Myctophum asperum , M. orientale , Lampadena luminosa and Symbolophorus evermanni ), Kuroshio east group ( Hygophum reinhardtii , Lampanyctus alatus , Diogenichthys atlanticus , Lobianchia gemellarii , M. nitidulum , Benthosema suborbitale , Lampadena sp. and Ceratoscopelus warmingii ) and Pan- Kuroshio group [ Diaphus stubby type (mostly D. garmani ) and D. kuroshio ]. Larvae of the subfamily Lampanyctinae were distributed in shallower (0–30 m) waters than those of the subfamily Myctophinae (50–150 m), while this relationship was opposite of the night-time depth distribution of adults of the two subfamilies.     

Population prioritization for conservation of imperilled warmwater fishes in an arid‐region drainage

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Issues for the conservation and management of Falkland Islands freshwater fishes

• 1. The Falkland Islands, in the cool‐temperate south‐western Atlantic Ocean, have an impoverished freshwater fish fauna, with only two indigenous species certainly present there: the Falklands minnow, Galaxias maculatus, and the zebra trout, Aplochiton zebra. Additional species whose presence there is uncertain are the southern pouched lamprey, Geotria australis, and the Patagonian puyen, Galaxias platei. Brown trout, Salmo trutta, were introduced in the mid‐20th century, and sea‐migratory (diadromous) populations are widespread.
• 2. Distributions of zebra trout and brown trout, particularly, are complementary, suggesting that brown trout are having detrimental impacts on zebra trout. Zebra trout have suffered massive decline over the past few decades and remain largely in restricted areas that brown trout have not yet invaded.
• 3. Owing to their sea‐migratory habits, it can be expected that brown trout will eventually invade all significant streams on the Falkland Islands. This raises issues of serious concern since zebra trout are also probably sea‐migratory, and therefore need access to and from the sea to complete their life cycles. Therefore, any streams accessible to zebra trout are potentially accessible also to brown trout, raising the spectre that eventually brown trout will invade all the streams where zebra trout persist.
• 4. The existence of landlocked populations of zebra trout provides some form of protection from brown trout invasion, though a landlocked stock does not represent the full behavioural and genetic diversity of zebra trout in Falkland's waters, and must be regarded as a last resort means for conservation.

Copyright © 2001 John Wiley & Sons, Ltd.