达赉湖的餐条鱼生物学

本文报道了达赉湖的餐条鱼生物学，内容包括年龄和生长、食性、繁殖、群体结构及渔业利用。达赉湖的　条鱼一龄平均体长（到尾叉的体长，后同）９０毫米，体重８．５克；二龄体长１０２毫米，体重１２．９克；三龄体长１０９毫米，体重１５．４克；四龄体长１２５毫米，体重１８４克；五龄体长１５６毫米，体重２３．３５克。体长体重关系式：Ｗ＝０．０３１０Ｌ２．５１７１。是以浮游动物为主要饵料的杂食性鱼类。一龄即达性成熟；性比为１．０♀：１．３６♂；个体繁殖力３５５２～１６４２０粒，平均９９４４粒。６～７月在湖的岸边产卵，卵属粘性。群体由１～５个龄组组成，１２００尾样品平均年龄为２．６５；８０．１～１００毫米体长组的个体为主要渔获对象，占整个渔获物的７５．５％，条鱼目前是这赉湖第一位的经济鱼类，９０～９２年条鱼平均产量为８２８万公斤，占总鱼产量的９０．２％。     

赤鼻棱鳀的摄食与生态转换效率

１９９８年９月利用对虾养殖土池中的赤鼻ＬｅｎｇＬｉ进行了摄食与生态转换率的观察研究。结果显示，赤鼻ＬｅｎｇＬｉ是典型的浮游动物食性鱼类，偏食大型桡足类和介形类，无明显摄食节律性；消化道日均食物含量１．２１９６ｇ（１００ｇ）＾－１．ｄ＾－１，排空率０．３１４１ｇ（１００ｇ）＾－１．ｈ＾－２，日摄食量１０．８１３５ｇ．（１００ｇ）＾－１．ｄ＾－１；食物转换效率３５．０８％，能量转换效率３９．３０％。渤海赤鼻ＬｅｎｇＬｉ的年饵料需求量约为８７０００ｔ。研究结果表明，较高的生态转换效率保证了赤鼻ＬｅｎｇＬｉ较高的生长率，因此较低的浮游动物生物量可支持这一鱼种较高的生产力，这被认为是渤浮游动物生物量大幅下降的同时赤鼻ＬｅｎｇＬｉ资源量却迅速增加的原因之一。     

洪门水库渔业资源调查报告

洪门水库为江西第二大水库，可养鱼面积７．６５万亩，消落区面积２－３万亩，浮游植物生物量４．４０６ｍｇ／Ｌ，浮游动物生物量２．４５ｍｇ／Ｌ。初步估算，水库鱼产力在３１．３６ｋｇ／亩，而目前单产水平保持在１６．６ｋｇ／亩上下。渔获量以镛鱼为方，鲢鱼次之。全库鱼类９６种，经济鱼类占８５％，如适度开发，水库鱼产力将明显提高。     

渤海主要生物种间关系及食物网的研究↑（*）

根据１９９２年－１９９３年渤海增殖生态基础调查大面定点底拖网试捕的渔获物，对渤海２７种鱼类和１０种虾蟹类的３８０１个胃含物样品进行了分析，并与１０年前渤海鱼类的食性进行了比较。结果表明：蓝点马鲛、小黄鱼和白姑鱼等主要捕食鱼类胃含物中鱼的比例较１０年前明显增加，鱼类的食性类型无明显变化。渤海低级肉食性鱼类的营养级由１９８２－１９８３年的平均２．４上升为２．５，中、高级肉食性鱼类的营养级分别由原来的平均３．２和３．８降为２．８和３．３。渤海主要鱼类之间饵料重叠系数大于０．６的占１５％。鱼为渤海多数中、高级肉食性鱼类的主要摄食对象。     

东海高营养层次鱼类功能群及其主要种类

在2000年秋季和2001年春季东海120°~126.75°N、25.75°~31°E范围内的两次大面积调查基础上,以占渔获量90%的鱼类为研究对象,分析东海春、秋两季2个鱼类群落的功能群。结果表明,东海高营养层次鱼类群落包括7个功能群,即鱼食性鱼类、虾/鱼食性鱼类、虾食性鱼类、虾蟹食性鱼类、底栖动物食性鱼类、浮游动物食性鱼类和广食性鱼类。其中东海近海春季鱼类种群由浮游动物食性鱼类、底栖动物食性鱼类、鱼食性鱼类和虾食性鱼类4个功能群组成,秋季鱼类种群由虾/鱼食性鱼类、虾食性鱼类、广食性鱼类、虾蟹食性鱼类、鱼食性鱼类和浮游动物食性鱼类6个功能群组成;东海外海春季鱼类种群由鱼食性鱼类、底栖动物食性鱼类、浮游动物食性鱼类和虾食性鱼类4个功能群组成,秋季鱼类种群由浮游动物食性鱼类、虾/鱼食性鱼类、鱼食性鱼类、虾食性鱼类和底栖动物食性鱼类5个功能群组成。从生物量组成上分析,在各鱼类群落中发挥主要作用的功能群不同,春季东海鱼类群落以浮游动物食性鱼类功能群为主,而秋季以鱼食性鱼类功能群为主。其中带鱼、白姑鱼、六丝矛尾■虎鱼、多棘腔吻鳕、龙头鱼、小黄鱼、细条天竺鱼、发光鲷、、花斑蛇鲻、短鳍红娘鱼、竹荚鱼、条尾绯鲤、黄鳍马面、黄条等15种鱼为各功能群的主要种类。群落种类组成的差异,同种类体长分布的差异,以及饵料基础的时空变化是导致东海各鱼类群落功能群组成差异的主要原因。     

长沙水产五十年

长沙水产业已历经了五十个春秋,同其它的经济行业和社会发展一样走过了一段艰难曲折、探索前进最后迈向健康发展之轨的历程。５０年来,全市的水产品总产量从１９４９年的０．４２４万ｔ,增加到１９９８年的７．７４万ｔ,增长了７．３２万ｔ;养殖水面由建国初期的１．４３万ｈｍ２,到１９９８年增长到３．１０万ｈｍ２,增长了１．６７万ｈｍ２;渔业总产值由１９４９的１９３万元,到１９９８年的３．６４亿元,增长３．６亿元。水产产值占农业总产值比重由１９４９年的１．１３%增加到１９９８年的４．６７%左右;水产品的人均占有量从１９４９…     

渤海渔业资源结构、数量分布及其变化↑（*）

通过１９８２年～１９８３年和１９９２年～１９９３年分季底拖网调查，分析了渤海渔业生物资源的结构、数量分布及其季节间和１０年间生物量的变动情况及原因。结果表明，渤海渔业生物优势种与１０年前相比发生了较大变化，鱼已代替黄鲫成为渤海鱼类资源最丰富的种类，斑的生物量亦有较大增加，而小黄鱼、蓝点马鲛的生物量则大幅度下降。中上层鱼类占总生物量的比例增加，底层鱼类则下降，软体动物除春季外都下降，甲壳动物各季都有不同程度的下降。渔业资源密集分布区由莱州湾－黄河口一带水域变为秦皇岛和龙口外海水域。总生物量各季都下降，降幅为９．７％～８４．２％。渔业资源质量较１０年前大为降低，经济价值低的小型中上层鱼类已成为渔业资源的主要成分。     

陆水水库的浮游甲壳动物

陆水水库是一座具有防洪、发电、航运、养殖等多功能的大型水库。为了合理开发利用陆水水库的渔业资源，于１９９１年１月、４月、７月、１０月共四次调查了陆水水库的浮游甲壳动物。陆水水库有浮游甲壳动物４３属９２种及亚种，其中枝角类２４属６１种及亚种，桡足类１９属３１种，浮游甲壳动物年平均数量为７６．２ｉｎｄ／Ｌ，年平均生物量为１．３７９ｍｇ／Ｌ，每年可提供浮游动物食性鱼类６．７×１０＾５ｋｇ。     

辽西海域日本对虾生产性移植放流试验

１９９８年５月 ２４～２９日，在辽宁省葫芦岛市连山湾近岸水域放流体长１０．６±１．１ｍｍ的日本对虾２ ７９８．８万尾。 ８月中旬～１０月中旬期间，沿岸作业的 ５３４只渔船兼捕到本种商品虾 ２４．５ ｔ，平均体长 １４７．３ｍｍ，平均体重 ４０．７ ｇ，相当于 ６０．３万尾，回捕率为 ２． １５％，放流投资与增殖虾产值的比例为 １：５．４，效果良好。     

长吻Wei生态对策的Bayes模式判别

选择生态对策从典型的－选择类型到典型的ｒ－选择类型的６组１３种鱼作参照物，以渐近体长，渐近体重，生长系数，初次性成成熟年龄，最大年龄，瞬时自然死亡率和种群繁殖力系数等７项生态学参数作指标，用Ｂａｙｅｓ判别法建立６组鱼类的判别函数估计式ｙｋ（ｘ）（ｋ＝１，２，．．６）     

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).