文蛤的性腺发育和生殖周期

应用组织学方法对浙南池塘养殖的文蛤的性腺发育、生殖周期和肥满度进行了周年变化的研究。结果表明,文蛤的性腺发育具有典型双壳贝类特征,性腺发育过程可分为增殖期、生长期、成熟期、排放期、休止期5个时期,并对上述5期的宏观肉眼观察特征及微观切片观察特征进行了描述。浙南池塘养殖的文蛤性腺发育过程以1年为1个周期,成熟排放期在5月下旬至8月中旬,水温21.8～31.0℃,繁殖盛期为6月下旬至7月下旬,水温为25.0～30.0℃。月平均肥满度最高为6月份的8.84%,最低为1月份的3.21%。论文还讨论了1龄文蛤性腺发育、文蛤性腺成熟和排放与积温的关系。     

海湾扇贝性腺发育的生物学零度

性腺发育的生物学零度是生物的繁殖习性和生物积温研究中的一个重要指标。正如菊地省吾提出皱纹盘鲍性腺发育的生物学零度以后,人们已可以通过控制积温的方法有效地预报和控制鲍鱼的产卵。因此研究海湾扇贝性腺发育的生物学零度,在海湾扇贝的繁殖理论研究以及海湾扇贝的工厂化人     

黄海北部虾夷扇贝性腺发育及繁殖规律研究

通过性腺指数周年监测及性腺的组织切片观察,对黄海北部虾夷扇贝性腺发育及繁殖规律进行了研究。试验结果表明,虾夷扇贝性腺发育可划分为5期,即增殖期(Ⅰ期)、生长期(Ⅱ期)、成熟期(Ⅲ期)、排放期(Ⅳ)和休止期(Ⅴ期)。性腺周年变化规律是,11—12月为增殖期,1—2月为生长期,3月为成熟期、4—5月为排放期,6—10月为休止期。水温对性腺发育和产卵期的影响是,水温低性腺指数峰值高,产卵期相对滞后;水温高性腺指数峰值低,产卵期相对提早。     

长江蟹和辽河蟹性腺及肝脏指数的比较研究

统计分析了长江和辽河水系的河蟹在性成熟期其肝脏和性腺指数的变化规律。探讨了河蟹性腺指数和肝脏指数变化的相关关系。结果表明两水系河蟹在8～11月,肝脏指数越来越小。性腺指数越来越大。性腺指数的变化与肝脏脂数的变化密切相关,进一步证实了河蟹性腺发育的能量主要来源于肝脏。但两水系河蟹性腺和肝脏发育也有明显差异。辽河蟹性腺发育时间比长江蟹早1个月左右。     

鄱阳湖区雌鳝性成熟系数及肝指数的研究

统计分析了鄱阳湖区雌鳝在性成熟期其肝脏和性腺指数的变化规律,探讨雌鳝性腺指数和肝脏指数变化的相关关系。结果表明黄鳝在4月～7月,雌鳝性腺在Ⅲ期～Ⅳ期(6月以前),性腺指数与肝脏指数成一定的正相关。当雌鳝性腺发育到第Ⅳ期后,性成熟系数越来越大,肝脏指数却越来越小,进一步证实了黄鳝后期性腺发育及产卵时的能量主要来源于肝脏。     

梭子蟹胚胎发育与积温关系初步分析

通过对梭子蟹培育成抱卵和孵化出幼体所需积温的统计,分析梭子蟹人工育苗中的积温与其性腺发育的数量关系,根据三年的数据统计表明,梭子蟹抱卵积温和约为192℃.d;胚胎发育积温和约为319℃.d。     

人工诱导麦穗鱼亲鱼性腺同步发育技术研究

正本文研究了人工诱导麦穗鱼亲鱼性腺同步发育,雌鱼试验组的性腺指数明显大于对照组,已经达到了9.2±1.5a,而对照组为6.3±1.1b;雄鱼试验组的性腺指数明显大于对照组,其性腺指数达1.95±0.7a,而对照组性腺指数仅为0.46±0.3b。表明适宜的水温、光照及流水刺激利于亲鱼性腺发育,提高怀卵率和受精率。     

仿洄游培育美洲鲥亲本的性腺发育

为解决美洲鲥(Alosa sapidissima)人工培育亲本性腺发育不佳的问题,开展了美洲鲥亲本仿洄游的培育,研究观察了美洲鲥亲本卵巢和精巢不同发育阶段(II^V期)的形态特征及相关参数,确定了仿洄游培育美洲鲥亲本性腺初次发育的特征。结果显示:在美洲鲥仿洄游培育过程中,在卵巢、精巢发育前期(II期),雌雄亲本生长迅速;而性腺发育到III期后,雌雄亲本的生长滞缓,雌鱼亲本甚至出现负生长。仿洄游培育美洲鲥性腺初次发育(II^V期)过程中,雌雄亲本均有较高的肥满度,分别为1.55~2.07和1.56~1.71;卵巢发育Ⅴ期雌鱼亲本的肥满度(2.07)显著高于在卵巢II^IV期亲本(1.55~1.67);而雄鱼亲本肥满度在精巢发育各阶段(II^V期)均无显著性差异。仿洄游培育美洲鲥性腺发育良好,雌雄亲本的性腺指数均较高,性腺发育Ⅴ期雌雄亲本的性腺指数(GSI)分别为(26.10±6.46)(18.88~33.62)和(5.18±0.68)(4.49~6.11)。研究表明,仿洄游培育的水温(10.8~30.8℃)和盐度(1~15)的周年变化符合美洲鲥亲本性腺发育的要求。     

人工养殖条件下云南盘鮈成鱼性腺发育及周年变化

采用常规解剖学和组织学方法,研究人工养殖条件下云南盘鮈（Discogobio yunnanensis）成鱼性腺发育及周年变化情况,为云南盘鮈全人工化繁殖提供基础资料。实验时间为2016年6月至2017年6月,每月中旬解剖成鱼取性腺,雌雄各5～8尾,活体状态下测量常规生物学数据,解剖后肉眼观察性别及性腺发育情况,并记录色泽等其他外形特征。取性腺称重并测量其长度和宽度,计算其性腺成熟系数（GSI）,观察其性腺发育状况。结果表明,云南盘鮈在人工养殖条件下可以性成熟,并能繁殖后代。卵巢发育可分为Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ期,Ⅱ期卵巢持续时间最长（6-11月）,11月开始出现Ⅲ期卵巢,12月主要为Ⅱ、Ⅲ期卵巢,次年1-3月主要为Ⅲ期卵巢,4-5月主要为Ⅳ期卵巢,5月底到达Ⅴ期即成熟期,排卵后,进入短暂的Ⅵ期,后迅速退化至Ⅱ期。本实验没有观察到Ⅰ期性腺。云南盘鮈精巢发育也可分为5期。6-12月主要为Ⅱ期精巢,12月开始出现Ⅲ期精巢,以Ⅱ、Ⅲ期精巢过冬;次年1-3月主要为Ⅲ期精巢,含少量Ⅱ、Ⅳ期精巢,4月主要为Ⅳ、Ⅴ期精巢,5月全为Ⅴ期精巢,6月则以Ⅱ期精巢为主,含少量Ⅴ、Ⅵ期精巢。云南盘鮈卵巢成熟系数为1%~18%,最大成熟系数18%;精巢成熟系数为0.2%~8.0%,最大成熟系数为8.0%;性腺成熟系数在4-6月出现一次高峰,成熟系数变化趋势与周年变化一致,说明云南盘鮈为一次产卵类型鱼类,且繁殖期集中在5月底至6月初。     

浅析刺参工厂化育苗的关键技术

1亲参的选择 1．1亲参的选择 池塘养殖的刺参与自然野生刺参质量并不相同，最好选择池塘养刺参，因为它发育较同步，比较肥满。首先皮肤无损伤，未排脏，其次个体大小在250～350g2．间。性腺指数是刺参性腺发育程度的主要指标，占体重15％以上；体壁指数是亲参肥度的主要指标，占体重50％以上。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.