紫贻贝和厚壳贻贝杂交及F1代杂交优势初探

2005-2007年对紫贻贝(Mytilus gallo provincialis)和厚壳贻贝(Mytilus coruscus)种间进行了杂交生产性试验,通过亲贝强化培育、确认雌雄亲贝、改革育苗水体交换方法、投喂混合单细胞藻类、流水培养附着稚贝等技术,获得F1代.结果表明,正交F1代幼虫的成活率明显高于反交F1代和厚壳贻贝,在幼虫培育前期与紫贻贝的成活率相当,但随着幼虫的发育有高于紫贻贝的趋势.正交F1代幼虫的壳长和壳高在培育阶段的前期生长与紫贻贝相当,低于厚壳贻贝,高于反交F1代;但后期的生长明显增快,并高于反交F1代和其他两种贻贝.各试验组贻贝海区养殖的成活率在90%以上,正交F1代最高,显著高于反交F1代.各试验组生长特性,正交F1代紫贻贝厚壳贻贝反交F1代.其中正交F1代获附着稚贝3.77×109 ind.正交F1除在孵化率上低于紫贻贝、厚壳贻贝外,在壳长、壳高、成活率等方面指标具有一定杂交优势,而反交F1代的杂交优势不明显.     

中国蛤蜊生产性人工育苗试验

2016～2017年,对中国蛤蜊(Mactra chinensis)生产性人工育苗技术进行了试验研究,2016年培育出平均壳长3.5mm幼贝0.46亿粒;2017年培育出平均壳长3.8mm幼贝0.14亿粒。试验发现,中国蛤蜊在丹东近海自然海区繁殖盛期在5月中旬～6月中旬,雌雄性比约1∶1;壳长5cm左右的亲贝产卵量50万～75万粒/个,受精卵为沉性卵,卵径55μm;在水温23～24℃,盐度26‰、pH值8.0的条件下,受精卵经18h发育为D型幼虫,壳长75μm;幼虫经13～14d培育,壳长280～300μm时开始附着变态为稚贝,日生长量15.9～16.5μm;稚贝经30d培育,平均壳长可达35～38mm,平均日生长107～117μm。     

施氏獭蛤稚贝中间培育与海区养殖试验

施氏獭蛤稚贝中间培育和海区养养殖试验在雷州市覃斗镇英岭村海区进行,结果显示:经过35d的中间培育,稚贝壳长、壳高、壳厚平均值分别为23.1、11.2、6.2mm,平均重量1.8g,成活率达53%。经过一年的海区养殖试验,壳长、壳高、壳厚平均值分别为68.2mm、33.5mm、19.3mm,体重达40g以上。     

皱肋文蛤规模化人工育苗技术初步研究

为促进皱肋文蛤养殖业健康持续发展,提供批量优质苗种,研究开展了皱肋文蛤规模化人工育苗试验,育苗全程投喂人工培育的单胞藻。结果表明:分六批次催产皱肋文蛤亲贝580 kg,共获受精卵40.336×10~8粒,孵出D形幼虫总量为28.437×10~8只,受精卵孵化率为70.5%;浮游幼虫培育7 d后开始变态附着,获初附稚贝15.157×10~8粒,幼虫变态附着率为53.3%;再经约33 d培育,共培育出平均壳长916.17μm的皱肋文蛤稚贝8.986×10~8粒,育苗成活率为31.6%,平均单位出苗量为249.6×10~4粒/m~2。     

大竹蛏生产性人工繁育试验

2007年对大竹蛏进行了生产性人工繁育试验。对亲本不同批次催产效果、不同规格亲本产卵差异、孵化密度进行了比较,研究了D形幼虫发育与温度的关系以及幼虫发育各阶段生长规律等,结果显示,大竹蛏属分批成熟、分批产卵的潜居性贝类,不同批次个体平均产卵量(36~118)×104cell,个体总产卵量294×104cell。壳长8~10 cm的亲贝产卵量大,催产效果好。受精卵适宜的孵化密度为5~10 cell/mL。在水温21~24.5℃条件下,D形幼虫经8~5 d生长,发育变态为附着稚贝。D形幼虫壳长日生长33.33±4.22μm,1 mm前的稚贝壳长日生长108.33±22.57μm,1~10 mm的稚贝平均旬生长量2.12 mm,10.4~30.6 mm的苗种平均旬生长量为2.02 mm。当水温下降到15℃后,大竹蛏苗种生长滞缓。2007年培育出壳长11.52±0.27 mm的稚贝2 165×104cfu,平均成活率12.1%。     

长肋日月贝个体发生观察及人工育苗初步试验

首次报道了长肋日月贝( Amusium pleuronectes )的诱导产卵及幼虫、稚贝培育.用阴干-流水刺激法,成功诱导亲贝产卵、排精.对胚胎和幼虫发生进行了观察.水温23.0～25.0℃,经诱导产卵的受精卵20 h可发育至D形幼虫.水温22.0～24.0℃时,D形幼虫经11 d培育到眼点幼虫期.投放附着基后,眼点幼虫在10 d内附着完毕.水温18.0～24.0℃时,稚贝经30 d培育平均壳长达(2.0±0.18)mm.此试验共培育壳长(2.93±1.15)mm稚贝49.6万粒.     

波纹巴非蛤人工育苗技术初探

2008年～2009年,对波纹巴非蛤人工繁殖、胚胎发育、幼体开口饵料、幼虫变态附着和稚贝培育技术等进行研究,人工育苗获得成功。结果表明,在自然水温29.6℃～23℃,盐度28～34,pH值7.8～8.4,溶解氧4～7mg/L的生境下,受精卵约17h发育成"D"形幼虫,第6～7d,幼虫个体大小180μm×165μm(壳长×壳高),开始变态附着。经约80d人工培育,共获得壳长3.4mm～15mm的波纹巴非蛤稚贝21.6万粒。     

不同花纹文蛤杂交育种初步研究

挑选不同花纹并且性腺成熟较好的文蛤亲贝进行阴干刺激,在水温约30 ℃,海水相对密度1.016～1.018,pH 7.9～8.1的条件下采用升温刺激、异性产物等诱导方法促使其产卵排精.共育出2组文蛤苗种.亲贝于2004年6月30日(即自交组)排放的精卵经过受精后,受精卵在底面积为0.1 m2、体积为60 L的水桶中,经过孵化、附着变态等生长发育过程, 至9月6日, 共得到平均壳长2.18 mm,壳高1.87 mm的稚贝8703个,共15.57 g;经过室内培养至12月8日,测量得到壳长8.32 mm, 壳高7.03 mm的幼贝1843个,共150 g.至2005年6月28日,得到壳长19.22 mm,壳高16.39 mm文蛤2.5 kg.亲贝于7月9日(即杂交组)排放的精卵受精后,经孵化、附着变态等生长发育过程,至9月6日,共得到平均壳长4.19 mm,壳高3.71 mm的稚贝12721个,共102.50 g.至12月8日,测量得到壳长15.32 mm,壳高12.93 mm的幼贝4999个,共4000 g.2005年6月28日,称量得到壳长28.06 mm,壳高22.73 mm文蛤30 kg.在文蛤幼虫培育及稚贝培育过程中,观察了文蛤稚贝生长状况及贝壳花纹的形成变化过程.试验中发现文蛤稚贝生长状况较好,并且稚贝在生长发育过程中贝壳出现不同形状的花纹.     

魁蚶增养殖技术试验

1魁蚶苗的中间暂养2004年4月自山东烟台购进苗种2 000万粒,稚贝壳长1 mm左右,首先经过浮筏式中间暂养培育成大规格苗种。中间育成要选择无风浪,水质清新,饵料生物丰富的海区,视稚贝的附着量多少,按一定稚贝数量(一     

栉孔扇贝春季升温育苗与保苗技术研究

栉孔扇贝Chlamys farreri在中国海水养殖业中占有十分重要的地位,但目前苗种来源仍多采用半人工采苗的方法,苗种数量和质量均无法保证,已经严重制约了产业的发展.2007年2～6月,笔者在红岛蛤原良种有限公司进行了春季升温育苗试验,采取在自然水温很低的情况下(6.9℃),逐步升温促熟,经过23 d室内亲贝暂养,在52 m3水体中共培养出库稚贝(壳长719.58±65.74 μm) 12.8×106粒,保苗后壳长4.923 mm×5.661 mm稚贝8.3×106粒.此次出库稚贝的中间培育采用改造后的虾池(5.33 hm2),在虾池中打桩拉浮绠,每隔1.5 m悬挂浮球一个,吊养保苗袋,虾池中水温适宜,饵料生物丰富,提高了稚贝成活率,平均保苗率高达65%.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

A novel approach to denitrification processes in a zero-discharge recirculating system for small-scale urban aquaculture

This paper presents an innovative process to solve the nitrate build-up problem in recirculating aquaculture systems (RAS). The novel aspects of the process lie in a denitrification bioreactor system that uses solid cotton wool as the primary carbon source and a unique degassing chamber. In the latter, the water is physically stripped of dissolved gaseous O₂ (by means of a Venturi vacuum tube), and the subsequent denitrification becomes more efficient due to elimination of the problems of oxygen inhibition of denitrification and aerobic consumption of cotton wool. The cotton wool medium also serves as a physical barrier that traps organic particles, which, in turn, act as an additional carbon source for denitrification. Operation in the proposed system gives an extremely low C/N ratio of 0.82 g of cotton wool/g of nitrate N, which contributes to a significant reduction of biofilter volume. The additional advantage of using solid cotton wool as the carbon source is that it does not release organic residuals into the liquid to be recycled. Operation of the system over a long period consistently produced effluents with low nitrate levels (below 10 mg N/l), and there was only a very small need to replace system water. The overall treatment scheme, also incorporating an aerobic nitrification biofilter and a granular filtration device, produced water of excellent quality, i.e., with near-zero levels of nitrite and ammonia, a sufficiently high pH for aquaculture, and low turbidity. The proposed system thus provides a solution for sustainable small-scale, urban aquaculture operation with a very high recovery of water (over 99%) and minimal waste disposal.     

Fertilization by refrigerator stored sperm of the Indian major carp, Labeo calbasu (Hamilton, 1822)

This study reports on the spermatological properties, and on the development of a protocol for refrigerator storage (4°C) of Labeo calbasu (Hamilton, 1822) sperm for artificial breeding. Volume, motility, concentration and pH of the freshly collected sperm were 2.21 ± 0.53 (μL g^?1 of fish weight) (mean ± SD), 95 ± 1 (%), 1.93 ± 0.44 × 10⁹ (cells mL^?1) and 7.56 ± 0.17 respectively. Sperm activation was evaluated at different osmolalities of NaCl solution, and motility ceased completely when osmolality of the extender was ≥287 mOsmol kg^?1. Sperm retained motility for 24, 72 and 108 h, after refrigerator storage when sperm were undiluted, suspended in Alsever's solution and suspended in Alsever's solution containing 5% methanol respectively. Fertilization rate of fresh eggs with sperm stored at 4°C in Alsever's solution and Alsever's solution containing 5% methanol was 77% and 60% with a hatching rate of 60% and 43% respectively. The fertilization and hatching success of the stored sperm suggests potential to use refrigeration for transporting genetic material to hatcheries for artificial breeding of L. calbasu in Bangladesh.     

Effects of metomidate anaesthesia or transfer to pur sea water on plasma parameters in ammonia-exposed Atlantic salmon (Salmo salar L) in sea water

Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l^–1 TA-N (total ammonia-N) in sea water in 1 m³ tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na^{+, Cl–, Ca2+ or Mg2+} levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).