瓣结鱼生物学特性及生殖力的研究

对从皖南山区河流中采集到瓣结鱼活体样本进行体长、体重测定,通过鳞片鉴定其年龄,研究其性腺发育及繁殖力。结果表明:瓣结鱼体长与体重呈指数函数相关,W=0.0182L~b,b=2.9949;绝对怀卵量6680~38704粒,平均24543粒;雌鱼成熟系数0.74~31.47,平均20.31,雄鱼成熟系数0.18~7.43,平均2.17;体长的相对繁殖力:y=789.19x-918.15,经计算得出体长相对繁殖力(F_M)为760.9粒/cm。     

黄河上游极边扁咽齿鱼人工繁殖试验

采取干导法进行人工授精,2年累计孵化极边扁咽齿鱼受精卵14万粒,平均受精率87.5%,发眼率77.5%,上浮率72%.在孵化水温10～14 ℃条件下,从受精到发眼平均积温为2012.5 ℃·h;从发眼到破膜平均积温为575 ℃·h;从破膜到卵黄囊吸收完平均积温为3734 ℃·h;鱼苗全部发育平均积温为6321.5 ℃·h.     

黄河上游拉西瓦水库欧白鲑Coregonus albula个体繁殖力研究

2012年3月，从芬兰引进欧白鲑(Coregonus albula)发眼卵40万粒，孵出仔鱼培育出平均体质量2.0 g/尾的鱼种放入青海省拉西瓦水库网箱养殖。2018年，网箱养殖欧白鲑平均体质量3 kg以上。实验在2019年2月捕捞41尾雌鱼，11尾雄鱼,研究欧白鲑亲鱼在我国青藏高原东北部的形态特征、个体繁殖力特征及个体繁殖力与生物学指标的相关性。结果显示，欧白鲑个体绝对繁殖力平均为77 600粒，个体体长相对繁殖力平均值1 564 eggs·cm^-1，体质量相对繁殖力平均25.2 eggs·g^-1。雌亲鱼性腺成熟系数在14.8%～52.6%之间，平均为32.4%；肥满度为0.019 g·cm^-3～0.032 g·cm^-3之间，平均为0.025 g·cm^-3。欧白鲑雌性亲鱼卵巢重与体质量、体长和体高呈极显著的正相关性。欧白鲑的个体绝对繁殖力与卵巢重量、体质量、体长和体高呈极显著的相关性。性腺成熟指数、肥满度与体高呈极显著的相关性。欧白鲑亲鱼体高与其个体繁殖力具有很好的相关性，可...     

极边扁咽齿鱼人工驯化及亲鱼培育研究

在人工模拟微流水条件下驯养极边扁咽齿鱼,放养时平均体重700g,经过8年的驯化养殖,平均体重达到1400g,成活率55.4%.采用颗粒配合饲料喂食驯养的极边扁咽齿鱼亲鱼可以达到性成熟,首次产卵时间与野生条件下的基本一致,但产卵周期长,从4月下旬开始,到6月上旬结束.     

繁殖季节黄颡鱼的性腺特征

对繁殖季节的黄颡鱼性腺进行连续观察,结果表明黄颡鱼卵巢为黄色圆筒状,由大小不同的三 种卵粒组成,卵径分别为1． 2～1． 4mm、1． 5～1． 6mm 和1． 7～2． 0mm,直径较大的金黄色卵粒中有大量卵黄 沉积,成熟较好,较小的卵颜色发白。精巢为乳白色,饱满有光泽,靠近生殖孔的部分晶莹透亮。黄颡鱼雌 鱼性成熟系数为21． 48%,雄鱼性成熟系数为0． 60%。体重35～85g 时,雌性个体相对繁殖力为76． 81～ 94． 72粒/ g,平均为84． 35粒/g,绝对繁殖力(Y)与体重(W)、体长(L)的相关方程为：Y=84． 74W- 55． 69、 Y=1416． 92L-14847． 24。     

厚唇裸重唇鱼繁殖生物学

2001-2009年在黄河上游水系进行土著鱼类资源调查,对收集到的235尾厚唇裸重唇鱼开展繁殖生物学研究。研究发现,厚唇裸重唇鱼繁殖期为4-6月,盛期为5月,在繁殖季节可借第二性征辨别性别,雌鱼和雄鱼均于6龄达到性成熟,雌鱼最小性成熟体长30.8cm,体质量380.7g,成熟系数15.21%;雄鱼体长27.2cm,体质量335.7g,成熟系数10.18%。厚唇裸重唇鱼绝对怀卵量为3043～42 158粒,相对怀卵量为7.9～37.2粒/g。成熟卵径(2.1±0.1)mm,卵子数为134.9粒/g;测定了产卵场的理化因子,集群繁殖需要约8℃的水温及其他一些生态因子刺激(海拔、水流、饵料等)。     

天津地区台湾泥鳅人工繁殖

于2017年4月底至6月初,进行台湾泥鳅的人工繁殖。亲鱼为天津鸿腾水产科技发展有限公司于2014年春天从我国台湾省引进。共选用台湾泥鳅约2 500kg,其中雌鱼约1 800kg;雄鱼约700kg,雌雄比例约为2.5∶1,雌鱼、雄鱼平均体重分别为121.88g、126.98g。雄亲鱼平均"胸鳍长/体长比"为15.71%,显著大于雌亲鱼的10.08%(P<0.001),并且雌、雄鱼之间数据不重叠。雌鱼背部肌肉注射绒毛膜促性腺激素(HCG)加鲫鱼脑垂体催产,雄鱼不使用催产素。人工授精后,将受精卵均匀地洒在孵化池内的网框上进行孵化,孵化水温18.5~22.5℃,受精约48~52h后破膜孵化。雌鱼每尾产卵量28.7g,平均每克卵数2 061粒,受精率82.98%,平均孵化率97.4%。2017年获得水花约7亿尾。     

黄颡鱼亲鱼培育技术

亲鱼培育是黄颡鱼人工繁殖的关键环节,培育效果的好坏直接影响育苗的成败.河北省水产良种场在2002～2005连续四年进行了池塘培育黄颡鱼亲鱼试验,均取得了较好效果,2005年催产前经测量,雌鱼性腺成熟系数平均为22%,雄鱼性腺成熟系数平均为0.6%.现总结如下:     

白龙江上游黑体高原鳅生物学研究

对2006年5～10月和2007年7～8月采于白龙江上游的200尾黑体高原鳅进行生物学研究.体长40.3～117.26mm,体重1.20～20.19g.脊椎骨数4 35～41 1.年龄可分为5个龄组,1龄→5龄数量表现为逐渐减少趋势.体重与体长呈显著的幂函数相关:W♂ ♀=0.0136L2.993,(R2=0.92).Fulton肥满度雌体平均为1.37,雄体平均为1.33;Clark肥满度雌体平均为0.96,雄体平均为1.03.幼体主要摄食摇蚊幼虫;成体主要摄食钩虾,蜘蛛和昆虫幼虫.雄鱼最小性成熟个体体长和体重分别为80.89mm和8.32g,性成熟系数为1.26%;雌鱼最小成熟个体体长为64.03mm,体重为2.71g,绝对怀卵量为942粒.绝对繁殖力波动在942～9200粒/尾之间,平均为3652粒/尾.     

温台渔场日本鲭的繁殖生物学特征

利用2012年春季在温台渔场对日本鲭(Scomber japonicus)繁殖群体连续6批取样的生物学测定数据,对其繁殖生物学特征进行了研究。结果表明,叉长340 mm以下群体中,雌雄比基本符合1∶1的性比关系;叉长340 mm以上群体中,雌鱼显著多于雄鱼(P0.05)。GSI随时间的变化结果显示,温台渔场日本鲭的主要繁殖期为3月中旬至4月中旬;不同时间段的雌鱼和雄鱼GSI均总体表现为雌鱼大于雄鱼(P0.05)。不同性腺发育阶段的平均摄食强度总体表现为雄鱼大于雌鱼。不同性腺发育阶段的雌性和雄性的肝指数均雌性显著大于雄性(P0.05)。绝对繁殖力范围为44 017~734 684粒/尾,平均值为(173 867±15 719)粒/尾,优势组为(10~30)×104粒/尾,占70.37%;相对繁殖力范围为187~1 403粒/g,平均值为(538±31)粒/g,优势组为(390~700)粒/g,占66.67%。卵径范围为0.27~1.22 mm,平均值为(0.86±0.01)mm,优势组为0.7~1.1 mm。温台渔场日本鲭的绝对繁殖力低于黄海北部而高于台湾海峡,相对繁殖力高于历史水平,平均卵径小于20世纪80年代,雌雄鱼的最小性成熟叉长均有一定程度的降低。以上结果都说明日本鲭为应对高强度捕捞和环境胁迫压力而采取增加相对繁殖力、减小卵径、提早性成熟等繁殖策略来维持种群数量和保证种群的延续。     

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.     

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.     

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.     

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).