美国硬壳蛤人工育苗技术研究(二)

美国硬壳蛤为中科院海洋所从美国引进的新贝类养殖品种,在国内尚无大规模育苗与养殖.我们于2003年进行了室内规模化人工育苗与室外保苗的自选课题研究工作,通过对硬壳蛤亲贝的性腺促熟培育,了解和掌握美国硬壳蛤的性腺成熟规律.通过对受精卵的孵化和幼体的发育进行探索,初步掌握了幼体发育的一般规律,为以后进行大规模生产提供可行性借鉴.     

硬壳蛤土池养殖技术

硬壳蛤（Mercenaria mercenaria Linnaeus）又称小圆蛤、北方帘蛤或美洲帘蛤。原分布于美国东海岸，是美国大西洋沿岸浅海和滩涂主要的经济双壳贝类之一。硬壳蛤为广温、广盐性贝类，对低盐和高温的耐受力均较强，同时具有较快的生长速度，一年即可达到性成熟。硬壳蛤对环境耐性强，对底质无特殊要求，能适应不同的底质养殖，在沙底、沙泥底、泥底和海岸床等多种底质的滩涂和浅海都可以正常生长、发育。我国的纬度与硬壳蛤自然分布的地理纬度相同，自然条件能满足其生长需要，因此适合在我国开展增养殖。本项目把硬壳蛤从我国北方引入福建，     

硬壳蛤的生物学特性及养殖技术初探

硬壳蛤（Mercenaria）原产地在美洲东海岸，是美国大西洋沿岸和滩涂的主要养殖贝类，营养和经济价值较高，贝壳可作为高级工艺品、装饰品的原料，从硬壳蛤中提取的蛤素能够抑制肿瘤的生长。硬壳蛤对低盐和高温的耐受力较强，为广温、广盐性贝类，生长速度较快，一年即可达到性成熟。对底质无特殊要求，在沙底、沙泥底、泥底和海岸床等多种底质的滩涂和浅海都可以正常生长发育。2004年7月中旬，丹东市从大连金州引进该蛤进行试养。试养获得了成功，说明硬壳蛤在丹东地区完全可以人工养殖。     

硬壳蛤与中国对虾池塘混养技术

硬壳蛤又称美洲帘蛤，原产于美国东海岸，是美国大西洋沿岸浅海和滩涂主要的养殖贝类。其味道鲜美，营养丰富，贝壳又是高级工艺品、装饰品的原料，提取的蛤素能够抑制肿瘤的生长，因此具有较高的经济价值和药用价值。辽宁锦州地区地处辽东湾北部，滩涂底质和水质等自然环境十分适宜美国硬壳蛤的生长。2006年初我们去大连丹东等地考察学习，     

美国硬壳蛤生物学特性及池塘养殖技术

美国硬壳蛤(Mercenaria)原分布于美国东海岸，是美国大西洋沿岸和滩涂的主要养殖对象，对低盐和高温的耐受力均较强，为广温、广盐性贝类，生长速度快，一年即可达到性成熟。对底质无特殊要求，在沙底、泥底和海岸床等多种底质的滩涂和浅海，都可以正常生长。美国硬壳蛤营养价值较高，贝壳又可作为高级工     

硬壳蛤与日本对虾池塘混养技术

硬壳蛤隶属瓣鳃纲、真瓣鳃目、帘蛤科，又称小圆蛤、北方帘蛤或美洲帘蛤。原分布于美国东海岸，是美国大西洋沿岸浅海和滩涂主要的经济双壳贝类之一。它个体大、肉质鲜美、营养丰富。硬壳蛤为广温、广盐性贝类，能在沙底、沙泥底、泥底和海岸床等多种底质的滩涂和浅海上正常生长、发育，具有较快的生长速度，一年即可达到性成熟。我国与硬壳蛤自然分布的地理纬度相近，自然条件能满足其生长发育需要，因此适合在我国开展增养殖。莆田市水产科学研究所2005年12月从山东引进硬壳蛤，在莆田市秀屿区北江围垦开展规模化土池人工育苗及养殖技术开发研究，     

台湾海峡

美国硬壳蛤(Mercenaria)原分布于美国东海岸,是美国大西洋沿岸和滩涂的主要养殖贝类,营养和经济价值较高,贝壳又可作为高级工艺品、装饰品的原料,由硬壳蛤提取的蛤素能够抑制肿瘤的生长.美国硬壳蛤为广温、广盐贝类,对低盐和高温的耐受力均较强,具有较快的生长速度,一年即可达到性成熟.其对底质无特殊要求,在沙底、沙泥底、泥底和海岸床等多种底质的滩涂和浅海,都可以正常生长、发育.2004年丹东市水产技术推广总站从大连金州引进该蛤进行池塘养殖试验,经三个月的试养获得成功.     

硬壳蛤虾池生态养殖技术

<正>硬壳蛤又称小圆蛤、北方帘蛤、美洲帘蛤,是美国大西洋沿岸浅海和滩涂主要的经济双壳贝类之一,其肉质细嫩,味道鲜美,营养丰富,富含蛋白质,其贝壳具有很高的工艺价值和药物价值,同时硬壳蛤还具有生长速度快、适应性强等特点。为了进一步优化我市养殖品种结构,提高养殖经济效益,丰富老百姓的菜篮子,2012年7月~2013年8月,     

贝类育苗技术之一美国硬壳蛤人工育苗技术总结

美国硬壳蛤(Mercenaria mercenaria)又称小圆蛤、北方帘蛤或美洲帘蛤。该贝属广温、广盐性种类,对环境耐性强,适应于不同底质养殖,生长速度较我国产的文蛤快,2周年即可达到壳长50mm以上的商品规格。为增加南通市海洋贝类养殖品种,挖掘广阔的浅海与滩涂潜力,同时也为发展规模化硬壳蛤增养殖提供种苗资源,笔者与浙江省海洋水产研究所合作,引进美国硬壳蛤亲贝,在江苏省如东县大豫镇某育苗基地,进行人工育苗试验。现将有关具体技术工作情况总结如下:     

美国硬壳蛤工厂化人工育苗技术

美国硬壳蛤（Mercenaria）属双壳类，帘蛤科，为广盐性贝类，生长速度快，一年即可达到性成熟。其营养丰富，市场价值高。由硬壳蛤提取的蛤素具有很高的医用价值，深受世界各地消费者的欢迎。2004年我站引进该蛤进行池塘养殖试验获得成功，2005～2006年开始进行工厂化人工育苗试验，现将其人工育苗的主要技术介绍如下，供参考。     

Mesocosm: A Reliable Technology for Larval Rearing of Diplodus puntazzo and Diplodus sargus sargus

Species diversification is today considered as a major issue for the sustainable development of the Mediterranean aquaculture. For successful propagation of any species however, larval rearing is considered a bottleneck and therefore the development of appropriate tools is essential. Mesocosm is a semi-intensive technology that facilitates larval rearing of several species integrating principles of both intensive and extensive aquaculture, which solves biological problems and many of their technical, human and economical consequences. The extensive (and now even the semi-extensive) strategy is used in the most critical segments of the rearing process during the early developmental stages, when larvae are still extremely weak, sensitive to intensive environment, easily stressed and difficult to feed. The intensive strategy is used as soon as larvae are considered mature enough to be reared easily using classical methods. The technology was used for the rearing of two species, with potential for aquaculture, the sharpsnout seabream (Diplodus puntazzo) and the white seabream (Diplodus sargus sargus). Three groups of each species were monitored for a period of 50–70 days post hatching. Survival for both species was about 54% at the end of the trials. Sharpsnout seabream larvae reached 19.6 ± 0.9 mm total length and 107.2 ± 31.9 mg body weight 50 days post hatching. White seabream larvae 60 days post hatching reached 32.7 ± 2.7 mm total length and 450 ± 70 mg body weight. In order to verify the economical viability of the technology, the individual production cost for each species was estimated and reached ¢0.027 for white seabream and ¢0.043 for sharpsnout seabream. Results indicate the reliability of the technology for the larval rearing of the two species.     

The effect of density in larval rearing of the pullet carpet shell Venerupis corrugata (Gmelin, 1791) in a recirculating aquaculture system

The pullet carpet shell Venerupis corrugata is an economically valuable species in several European countries, however, nowadays stocks are under high fishing pressure. Hatchery production of juveniles for release is a major contributor to strengthen the stock and consequently improve the sustainability of the natural stocks. This study aimed to determine the feasibility of rearing V. corrugata larvae with different larval densities (10, 40 and 200 larvae per mL) in a recirculating aquaculture system (RAS), compared with the traditional larval rearing methodology (Batch). The mean survival, growth and metamorphic rate of V. corrugata larvae in RAS was higher (11.1%; 71.3 μm; 21.6% respectively) than in the Batch system, in all tested densities. The larval growth was not affected by the initial density until 40 larvae per mL, however, 200 larvae per mL decreased the larval growth in length nearly 54 μm. The larval rearing time was shortened in 2 days in the RAS system. The physical, chemical and microbiologic parameters suggested that the tested densities were not excessive to disturb the biofilter stability of RAS. The V. corrugata larval rearing performed at high larval stocking densities in RAS system present a reduction in the operating costs to produce this species.     

Rearing river lamprey <Emphasis Type="Italic">Lampetra fluviatilis</Emphasis> (L.) larvae under controlled conditions as a tool for restitution of endangered populations

A method for actively protecting river lamprey and increasing the number of river lamprey populations is presented as protocol of rearing stocking material. The objective of the study was to accommodate lamprey larvae during the most critical life period under controlled conditions until they reach a sufficient size, which will increase their chances to survive in the natural environment. The eggs obtained from wild breeders were incubated in Weiss’s jars at the water temperature of 12 °C. The larvae were reared in tanks set up in closed recirculating aquaculture systems. During the rearing period, the water temperature was 20 °C and the density of larvae was 150 individuals per 1 dm² of bottom. In the initial rearing phase, the main focus was on the type of feeds and the nourishment method. It was determined that the most suitable feed type was Artemia nauplii combined with Hikari dry food. Additionally, the type of substrate was tested under controlled conditions. In this case, the optimum one was composed of sand of the grain size between 0.3 and 0.5 mm. The experiment proved that it is possible to successfully conduct river lamprey larvae rearing under controlled conditions. The growth rates are comparable to or better than those achieved under natural conditions. After 30 days of the rearing period, the lamprey larvae were 25 mm long. The results create a possibility to develop a technology for the restitution of river lamprey and other lamprey species, which are endangered throughout the world.     

Larval Age at Stocking,Growth, and Survival During Fingerling Production of the Endangered Sun Catfish,Horabagrus brachysoma

An experiment was conducted to ascertain the initial rearing period required for Horabagrus brachysoma larvae before releasing them into the nursery tank for fingerling production. Hatchlings were reared for 7, 14, or 21 days in larval rearing tanks before stocking to nursery tanks. The 7-day-old larvae were significantly smaller at the end of the 2-week nursery rearing, but over the course of nursing, the 7-day-old larvae caught up to the 14- and 21-day larvae. The specific growth rate (SGR) of 7-day larvae was highest among the three treatments. However, mortality of 7-day larvae was the highest among the groups. Hence, it appears important to rear the larvae at least 2 weeks before stocking for fingerling production so as to increase survival rate.     

A spatiotemporal study of bacterial community profiles associated with Atlantic bluefin tuna larvae,Thunnus thynnus L., in three Mediterranean hatcheries

During the first 2 years of larval rearing trials with Atlantic bluefin tuna, survival was a challenging issue. As bacterial colonization of the gut has been shown to play a key role for other species, we studied the profiles of the microbiota associated with individual larvae at different stages in three distant hatcheries. The Bacterial Community Profile (BCP) was quantified based on PCR‐DGGE analyses of partial amplicons from 16S rDNA. Considerable individual variability in BCP was observed before onset of feeding, and the BCP did not show regular fluctuation during ontogenesis. Microalgae were added to the rearing tanks in two of the three hatcheries, but it was not possible to distinguish the effect of location from the effect of algal addition on BCP. In one hatchery, the larvae were reared either with algal addition or in mesocosm, but due to high individual variability, no significant difference in BCP was detected between the two groups. It was hypothesized that this variability was caused by differences in health, physiological status and developmental stage of the larvae. A practical conclusion from the study is the need to analyse a considerable number of individuals to reflect statistically significant differences between the microbial communities associated with rearing groups.     

Remarkably high survival rates under dim light conditions in sutchi catfish <Emphasis Type="Italic">Pangasianodon hypophthalmus</Emphasis> larvae

The sutchi catfish Pangasianodon hypophthalmus is an important species for aquaculture in Southeast Asia. However, larvae typically have low survival rates due to their predilection for cannibalism during rearing. This study investigated larval feeding behavior and rearing conditions. The former experiments were performed to elucidate the role of sensory organs in feeding, and the latter experiments examined the effect of dim light on larval rearing and survival rates. Neither lighting conditions (light and dark) nor blocking of free neuromasts by streptomycin had significant effects on feeding behavior. Therefore, the feeding behavior of sutchi catfish larvae most likely depends on chemosensing rather than visual sensing. In the later experiments, larval rearing at 0.1 l× yielded significantly higher survival rates than other lighting conditions (0.00, 1, 10, 100 l×). Survival in the 0.1 l× group was almost three times higher than in the 100 l× group. Moreover, larvae reared under 0.1 l× showed steady growth. Therefore, it is concluded that 0.1 l× is the optimum light intensity for sutchi catfish larval rearing.     

Estimation of flow in a rearing tank of marine fish larvae by simplified numerical computation—a case of two-dimensional flow

Marine fish larvae are fragile against physical stress. However, few studies have been conducted to evaluate the flow field in a rearing tank, which is assumed to provide a high degree of physical stress to marine fish larvae. The flow field in a rearing tank (volume of 1 m³) is generated by aerators, which are commonly used to provide oxygen.

This paper is a report on the estimation of stationary flow in the rearing tank of marine fish larvae. The larvae are seven band grouper larvae of Epinephelus septemfasciatus, which have a very low survival rate immediately after the hatching of eggs. The experiments of rearing of seven band grouper larvae were carried out using rearing tanks with four aeration rates (1000, 200, 50 ml/min, and no aeration). The effects of aeration on the survival and floating death of seven band grouper larvae were examined. The experiments confirmed that the mass mortality of seven band grouper larvae depends on the flow rate in the rearing tank. Aeration at 200 ml/min resulted in the highest survival and growth rates of grouper larvae.

Larvae-rearing experiments provided evidence that the flow rates of the rearing tanks are very important design aspects of rearing tanks. The estimation of flow in a rearing tank for an aerating rate of 200 ml/min was carried out by numerical calculation. The computation was simplified by a two-dimensional flow based on experimental results. The calculated flow in the rearing tank was compared with the experimental one. The calculation of the stationary flow in the rearing tank showed good qualitative and quantitative agreement with the experimental results. The numerical estimation of the flow in a rearing tank of marine fish larvae was confirmed to be effective and satisfactory for the design of a tank that would provide optimum performance.     

罗氏沼虾早繁苗中间培育及商品虾两茬养殖技术探讨

在上海地区进行罗氏沼虾商品虾两茬养殖，关键是抓好早繁苗的中间培育和第二茬养殖用苗的囤养。采用温室保温、锅炉增温和气泵充气等技术措施对罗氏沼虾的早繁苗进行集约化中间培育，可以提前１个月，在５月１０日左右为商品虾的第一茬养殖培育出大规格虾苗。利用室外土池囤养晚苗，为第二茬养殖培育虾苗，重点应处理好饲料投喂与水质调节之间的矛盾。     

Tolerance response to water pH in larvae of two marine fish species, gilthead seabream, Sparus aurata (L.) and Senegal sole, Solea senegalensis (Kaup), during development

Gilthead seabream, Sparus aurata (L.) and Senegal sole, Solea senegalensis (Kaup) are two fish of primary importance in Mediterranean aquaculture. In the present study, the larvae of these species were exposed to different rearing‐water pH during 24 h to examine their tolerance. The 24‐h pHL50 values were calculated with low and high pH values at 7, 20 and 32 days after hatching (DAH) in S. senegalensis larvae, and 12, 20 and 52 DAH in S. aurata larvae. Low 24‐h pHL50 values ranged between 4.88 and 5.76, whereas high 24‐h pHL50 values ranged between 8.94 and 9.57 in S. senegalensis larvae. S. aurata larvae showed values of low 24‐h pHL50 that ranged between 4.82 and 5.55, whereas values of high 24‐h pHL50 ranged between 8.66 and 9.26. Both species showed similar tolerance response at all the tested ages. The high 24‐h pHL50 values found were close to pH values that eventually can be reached in the rearing tanks. The pH should be carefully controlled in rearing water during the first development stages of both species.     

UV treatment in RAS influences the rearing water microbiota and reduces the survival of European lobster larvae (Homarus gammarus)

The rearing environment is important for a stable production of good quality lobster juveniles. By providing an environment excluding pathogens and dominated by mutualistic bacteria, the probability of developing healthy host-microbe relationships and produce healthy juveniles is increased. Disinfection of water and sudden increase in the supply of organic matter in culture tanks are processes that open for uncontrolled microbial regrowth in the rearing water. This increase the variability in the development of the microbiota between replicate rearing tanks and promotes selection for potentially harmful opportunistic bacteria. In two start feeding experiments with European lobster (Homarus gammarus) we compared the bacterial environment in three types of rearing systems: a recirculating aquaculture system (RAS) with UV treatment directly in front of the rearing raceways, a RAS without disinfection, and a conventional flow through system (FTS). The RAS with no disinfection was hypothesised to stabilise the microbiota of the rearing water, select against opportunistic bacteria, and reduce variability in production outcome between replicate tanks compared to the other systems. As predicted, the three different systems developed significantly different compositions of the microbiota in the rearing water and the larvae. On average, the survival of larvae in RAS without disinfection increased with 43 and 275 %, in the first experiment, and 64 and 18 % in the second experiment, compared to RAS with UV and FTS, respectively. Also, the RAS without disinfection showed less variability in the survival of larvae between replicate tanks and batches compared to the other treatments. The results are promising for controlling the microbiota of the rearing water to improve, increase and stabilise the production of marine larvae by competent use of water treatment and selection regimes. Based on the presented and previous work, RAS is recommended over FTS, and in RAS it is recommended to avoid point-disinfection of the recirculating water, to provide a stable and beneficial microbial environment in the cultivation of marine larvae.