四川裂腹鱼摄食习性与资源保护

对采自乌江上游的190尾四川裂腹鱼（Schizothorax kozlovi）进行了食性分析。结果表明,天然水域中四川裂腹鱼以水生昆虫、藻类、水生植物、环节动物、软体动物和原生动物等为食,其营养级为1.72级,属于底栖杂食性鱼类。主要饵料为水生昆虫,出现频率和重量比分别为76.30%和53.22%;其次为藻类,出现频率...     

珠江斑鱯的食性

根据对珠江斑鱯的资源调查结果,从饵料生物种类组成、出现频率、不同体长斑鱯的食物组成差异、食性的季节变化等方面研究了珠江斑鱯食性特点。表明天然水域中斑鱯主要以甲壳类、昆虫类、鱼类、环节动物、植物碎屑等为食,其中甲壳类的出现频率高达78．6％,水生昆虫的出现频率为45．8％。其食物类群的季节变化明显,但没有出现停止摄食的时期,斑鲼在春季的摄食强度最大,各类食物在春季出现的频率均高于其它季节,斑鱯摄食率和充塞度的季节变化是一致的。不同体长斑鱯的饵料有一定的转化或更替阶段,约170mm体长时为主要饵料转化的第一阶段,约240mm体长时为主要饵料转化的第二阶段,随着斑鱯体长的增长,其摄食饵料的个体变大,但种类减少。     

瓣结鱼食性的研究

以采自贵州境内清水江、都柳江的318尾瓣结鱼(Tor(Foliter)brevifilis brevifilis)为研究对象,从食物组成、摄食强度和摄食形态学等方面研究了瓣结鱼食性的特点。结果表明:瓣结鱼的食物由双翅目昆虫幼虫等17类饵料生物组成,并以双翅目昆虫幼虫的出现率最高。瓣结鱼的充塞度按春、夏、秋、冬季逐渐增高,季节性变化明显。充塞指数随体长生长显著减少,而摄食率则随体长生长逐渐增加。充塞指数和摄食率均以V期性腺个体为最低。瓣结鱼为底层杂食性鱼类。     

珠江水系大眼鳜的食性研究

根据对珠江大眼鳜的资源调查结果,从饵料生物种类组成、出现频率、不同体长大眼鳜的食物组成差异、食性的季节变化等方面研究了珠江大眼鳜食性特点.表明天然水域中大眼鳜主要以鱼类、昆虫类、植物碎屑等为食,其中鱼类的出现频率高达79.1%,虾的出现频率为53.97%.其食物类群的季节变化明显,但没有出现停止摄食的时期,大眼鳜在春季的摄食强度最大,大眼鳜摄食率和充塞度的季节变化皂一致的.不同体长大眼鳜的饵料有一定的转化或更替阶段,约140 mm体长时为主要饵料转化的第一阶段,约199 mm体长时为主要饵料转化的第二阶段,随着大眼鳜体长的增长,其摄食饵料的个体变大,但种类减少.     

元江越鳠的食性研究

研究了越鳠的食物组成、摄食强度和摄食形态学。样本251尾,2008年6月~2009年5月采自云南元江。结果表明：越鳠的食物由水生昆虫幼虫和小型鱼类等15类组成,水生昆虫幼虫和小型鱼类的出现率分别为73.8%和64.2%,所占比重分别为40.0%和46.9%,小型鱼类和水生昆虫幼虫为越鳠的主要食物。随着体长增加,食物类别减少,摄食强度降低;水生昆虫幼虫的出现率降低,成虫出现率增加;体长160 mm以上个体胃中出现陆生昆虫且其出现率持续上升。食物组成的季节变化明显,摄食强度的季节变化不明显。越鳠是一种偏肉食性的杂食性鱼类,主要摄食底层小型鱼类和水生昆虫幼虫。     

黑龙江黑斑狗鱼的食性及其随体长和空间的变化

为了解黑斑狗鱼（Esox reicherti Dybowski）的食性及其随体长和空间的变化，2022年10—11月用网目2～8 cm的流刺网和网目0.9～3.5 cm的定置刺网在黑龙江抚远和呼玛江段采集到138尾黑斑狗鱼，鉴定和测量其体长和体质量及胃含物种类与重量，研究摄食习性及其随体长和空间的变化。结果表明：这些黑斑狗鱼的饵料生物共有27种（包含未鉴定种），分为5个类群：鱼类、两栖类、甲壳类、水生昆虫和其他饵料，其中鱼类为黑斑狗鱼最主要的食物类群，数量在食物中占90.17%,然后依次为两栖类、水生昆虫和甲壳类。食物类群随着黑斑狗鱼的体长增加存在不显著的差异。体长350～450 mm组黑斑狗鱼主要摄食幼鱼；体长450～550 mm之间时开始摄食的饵料鱼个体增大，还摄食两栖类和少量水生昆虫；550～650 mm体长组的黑斑狗鱼则全部以鱼类为食。不同空间的黑斑狗鱼食物组成无明显差异。平均饱满指数和空胃率结果显示，黑斑狗鱼的摄食强度随着其体长的增长显著变化，摄食的高峰期在450～550 mm体长组之间，摄食强度无明显的空间差异。     

巨须裂腹鱼的亲鱼驯化

正巨须裂腹鱼(Schizothorax macropogon Regan)属于硬骨鱼纲、骨鳔鱼次亚纲、鲤形目、鲤科、裂腹鱼亚科、裂腹鱼属、巨须裂腹鱼科,地方名巨须弓鱼。主要摄食水中底栖生物、无脊椎动物、水生昆虫,同时也兼食着生硅藻类,喜栖息于河流入口交汇,水生一般在1米左右,底质一般为砾石或砂质的滩地。巨须裂腹鱼生活在雅鲁藏布江水系,是雅鲁藏布江水系中典型的单属性裂腹鱼种类,具有较     

长江口中华绒螯蟹雌蟹的食性和摄食强度

2017年10月-2018年4月逐月采集长江口生殖洄游期中华绒螯蟹(Eriocheir sinensis)雌蟹,运用胃含物分析法分析雌蟹抱卵前后饵料组成、摄食强度以及营养级,探讨其在长江口抱卵繁殖期间的摄食规律。结果表明:雌蟹摄食率、食物饱满指数、平均胃饱满度系数等3项指标具有明显的月份变动,抱卵前雌蟹的摄食指标在10-11月份(秋季)最高,12-2月份(冬季)最低;抱卵后雌蟹的摄食指标在12-2月份(冬季)最低,3-4月份(春季)最高。洄游期的雌蟹抱卵前后饵料来源多样,包括水生植物、藻类、甲壳类、多毛类、鱼类、软体动物、棘皮动物、卵、颗粒碎屑等。其中,藻类、颗粒碎屑和甲壳类为抱卵前的主要饵料,出现频率分别为68.13%、54.76%和19.05%;藻类、颗粒碎屑和水生植物为抱卵后的主要饵料,出现频率分别为70.35%、73.91%和25.39%。雌蟹抱卵前后饵料组成存在显著差异(χ^2=21.57,P<0.05),对差异贡献最大的饵料组成是颗粒碎屑(χ^2=8.32)、甲壳类(χ^2=5.49)和水生植物(χ^2=4.02)。雌蟹抱卵前后的营养级分别为3.60和3.10,平均营养级为3.35,属于第三营养级动物。     

长江中游宜昌至嘉鱼江段鳊食性研究

研究鳊(Parabramispekinensis)的摄食特征,为长江中游鳊资源的保护提供基础数据支撑。2016年9月至2017年8月在长江中游宜昌、荆州和嘉鱼江段使用三层流刺网进行了季度采样,对鳊肠含物的种类组成及时空差异进行分析。共采集鳊样本213尾,体长14.5～38.0 cm、体重67.0～978.1 g,其中肠道有食物的样本182尾。结果显示:在宜昌、荆州和嘉鱼江段,鳊全年摄食,且摄食强度存在明显季节变化。鳊充塞度以夏季最高、冬季最低;其中夏季肠道充塞度最高为5级,2、3级占52.42%;冬季最高为3级,0、1级占58.82%;春季和秋季最高充塞度均为4级,分别以1级、2级为主;鳊夏季摄食率最高(92.23%),略高于秋季(88.37%),明显高于春季(78.79%)和冬季(67.65%)。饵料生物主要为水生植物和浮游植物,其中浮游植物以颗粒直链藻(Melosira granulata)、变异直链藻(Melosira varians)和粗壮双菱藻(Surirella robusta)为优势种群。饵料生物种类组成在不同江段无明显差异,但呈现明显的季节变化,冬季以浮游植物出现率最高(100.00%),其他季节均以水生植物碎片出现率最高。建议在航道整治等涉水工程建设时,注重保护水生维管束植物及浮游植物,以保护鳊等草食性鱼类的饵料生物来源。     

新疆克孜勒河5种土著鱼食性分析

为探究克孜勒河 5 种土著鱼食物组成及其营养级, 本研究选取采自于克孜勒河的塔里木裂腹鱼(Schizothorax biddulphi)、宽口裂腹鱼(Schizothorax eurystomus)、厚唇裂腹鱼(Schizothorax irregularis)、叶尔羌高原鳅(Triplophysa yarkandensis)和长身高原鳅(Triplophysa tenuis) 5 种鱼样品共 46 尾作为研究对象, 运用传统形态学方法, 对样品 5 个摄食器官形态性状进行分析, 通过高通量测序技术分析其肠道食物组成, 并测定了碳、氮稳定同位素以分析其营养级。研究结果显示, 3 种裂腹鱼属鱼类摄食器官形态较为相近, 2 种高原鳅摄食器官形态基本一致; 厚唇裂腹鱼肠长比约为 2.95, 主要食物来源于初级生产者, 包括刚毛柽柳(Tamarix hispida)、野大豆(Glycine soja)和白刺(Nitraria tangutorum)等; 宽口裂腹鱼肠长比较短, 约为 2.56, 食物以初级生产者为主, 如二穗短柄草(Brachypodium distachyon), 也会捕食一些小型鱼类; 塔里木裂腹鱼肠长比较短, 约为 2.38, 食物以裂腹鱼属鱼类为主, 其次为白柠檬(Citrus latifolia); 叶尔羌高原鳅与长身高原鳅比肠长均小于 1, 肠道中裂腹鱼属鱼类丰度达到 95%以上; 塔里木裂腹鱼、宽口裂腹鱼和厚唇裂腹鱼营养级分别为 3.19、2.78 和 2.52, 叶尔羌高原鳅与长身高原鳅营养级为 3.44 和 3.55; 综合判断厚唇裂腹鱼属植食性鱼类, 宽口裂腹鱼为杂食性偏植食性鱼类, 塔里木裂腹鱼为杂食性偏肉食性鱼类, 叶尔羌高原鳅和长身高原鳅为肉食性鱼类。本研究拓展了对克孜勒河食物网的认识, 探明克孜勒河鱼类食物关系和营养级, 为克孜勒河鱼类资源保护及合理利用提供基础数据。     

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.     

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.     

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.     

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.     

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.     

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.     

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.