瓯江口海域夏秋季鱼类初步调查

2007年6月和9月对瓯江口海域通过拖网和张网捕获的鱼类进行初步调查。结果表明:渔获物中出现2纲12目33科55属72种鱼类,其中软骨鱼纲2目2科2属4种,占调查鱼类总种数的5.6%;硬骨鱼纲10目31科53属68种,占调查鱼类总种数的94.4%。根据其适温性类型可分为暖水性种、暖温性种和冷温性种,其中,暖水性鱼类有27种,占总种数的37.5%;暖温性鱼类有41种,占总种数的56.9%;冷温性鱼类有4种,占总种数的5.6%。渔获物中底层和近底层鱼类占多数,其中,底层鱼类共有27种,占总种数的37.5%;近底层鱼类共有30种,占总种数的41.7%;中上层鱼类共有15种,占总种数的20.8%。渔获物中海洋性鱼类占绝大多数,共有59种,占总种数的81.9%;河口性鱼类11种,占总种数的15.3%;洄游性鱼类2种,占总种数的2.8%。与相邻海区鱼类区系特征比较,瓯江口海域具有我国亚热带北部河口海湾的鱼类区系特征。     

秦岭黑河流域鱼类资源现状调查

为了解秦岭黑河流域鱼类资源现状,分别于2014年4、8、11月调查了黑河库区和上游水源地流域鱼类组成及其多样性。结果显示:调查共发现鱼类3目5科14属15种。其中鲤形目2科11属12种,占总种数80%;鲇形目2科2属2种,占总种数13.3%;鲑形目1科1属1种,占总种数6.7%。流域内优势种鱼类有拉氏(Phoxinus lagowskii)和秦岭细鳞鲑(Brachymystax lenok),稀有种有中华鳑鲏(Roodeus sinensis)、高体鳑鲏(Roodeus ocellatus)和黄颡鱼(Pelteobagrus fulvidraco)。黑河库区(海拔549 m)鱼类物种多样性高,群落结构稳定,而上游流域(海拔649~1 323 m)鱼类物种多样性急剧降低,群落结构脆弱。     

汝州市鱼类资源调查

2017年4月,我们对汝州市鱼类资源开展调查。本次调查共收集鱼标本37种,隶属于5目13科35属。其中鲤形目种类最多,占总种数的72.97%,其次是鲇形目和鲈形目均4种,占总种数的10.81%,其它目种类较少,只有1-2种。调查结果显示:汝州市鱼类在摄食、繁殖及栖息习性等方面呈现多样化特征。根据鱼类区系复合体学说,汝州市鱼类资源主要以江河平原区系复合体种类为主。     

南阳市社旗县鱼类资源调查

2016年12月对南阳市社旗县鱼类资源开展调查,共收集鱼标本34种,隶属于5目11科32属。其中鲤形目种类最多24种,占总种数的70.59%,其次是鲇形目和鲈形目,分别占总种数的11.76%和8.82%,合鳃目2种,占5.88%,鳉形目仅1种,占总种数的2.94%。社旗县鱼类物种较丰富,群落较复杂,鱼类在摄食、繁殖及栖息习性等方面呈现多样化特征。根据鱼类区系复合体学说,社旗县鱼类资源主要以江河平原区系复合体和南方平原区系复合体为主。     

碑坝河鱼类资源的调查及建设电站的影响

2016年4月和2017年4月,在已建和在建电站就近100m河段,用电捕器捕鱼和渔获物统计的方法,两次调查碑坝河鱼类资源,分析建设电站对鱼类资源的影响。结果共发现鱼类12种,隶属2目4科12属,其中鲤形目2科10属10种,占总种数83.3%;鲇形目2科2属2种,占总种数16.7%。鱼类群落优势种有棒花鮈Gobio rivuloides、短须颌须鮈Gnathopogon imberbis、宽鳍鱲Zacco platypus和马口鱼Opsariichthys bidens4种,稀有种有白甲鱼Onychostoma sima和齐口裂腹鱼Schizothorax prenanti 2种。鱼类的生态习性分析表明,大坝建设阻断河流,导致生境破碎化,运行的三座梯级电站造成碑坝河鱼类资源下降,在建和待建的两座电站运行后可能进一步带来不利影响。     

建阳市崇阳溪鱼类资源现状调查与保护对策

2007年10月至2012年2月对崇阳溪鱼类资源进行了调查,共设4个断面采样。结果共采集到鱼类75种,分属5目16科54属。种类组成以鲤形目鱼类为主,共4科39属51种,占总种数的68．0%,鲶形目次之,共4科6属11种,占14．7%;按科统计,鲤科鱼类最多,共40种,占总种数的53．3%,鮠科次之,共7种,占9．3%。4个断面渔获物的鱼类种类组成基本相同,但单种鱼类重量占总渔获物重量的百分比大于5%的主要种类组成差异较大。4个断面的单船（排）平均日捕捞量不同,回瑶断面的最高,芦上断面的最低。渔获物中个体小型化、低龄化现象严重。     

博爱县鱼类资源调查

2016年4月16日-4月19日,我们对焦作市博爱县的鱼类资源开展调查。本次调查共收集鱼标本19种,隶属于4目7科18属。其中鲤形目种类最多,占总种数的68.42%,其次是鲈形目占总种数的15.79%,鲇形目占总种数的10.53%,合鳃目只有黄鳝一种占总数的5.26%。调查结果显示:博爱县鱼类在摄食、繁殖及栖息习性等方面多样化程度较低,根据鱼类区系复合体学说,博爱县鱼类资源主要以江河平原区系复合体种类为主。     

进贤湖泊鱼类区系组成

本文叙述了进贤湖泊鱼类区系。共采集到鱼类标本８０种,分别隶属于１０目１７科６９属。其中鲤科鱼类分布最广,种类最多,占总种数的６３．７５％。鲥鱼、鲟鱼等在内湖已未见。     

汤阴汤河国家湿地公园鱼类资源调查

2018年4月至2021年10月,对汤河国家湿地公园鱼类资源开展了调查。结果表明,收集到鱼类23种,隶属于4目7科22属。其中鲤形目16种,占总种数的69.56%,鲈形目4种,鲇形目2种,分别占总种数的17.39%和8.69%,合鳃目1种,占总种数的4.36%,以鲤科种属最多,14属15种,占比65.22%;鱼类可划分为中国平原区系复合体、晚第三纪早期区系复合体、南方平原区系复合体和北方平原区系复合体。对鱼类种群特征、影响鱼类资源的因素等进行了分析。提出,为了更好地保护恢复鱼类资源,应优化增殖种类;规范鱼类引种;打击非法捕鱼;截污,保证下游汤河生态流量;增放人工鱼巢,提高幼鱼种群量;科学动态监测,维护汤河国家湿地公园生态系统的多样性、稳定性和持续性。     

长江安庆段春季鱼类群落结构特征及多样性研究

为了解长江安庆段春季鱼类群落结构及物种多样性现状,于2015年4-6月对该江段鱼类进行调查,共采集鱼类36种,隶属于5目、11科、31属;其中鲤科鱼类占优势,占总种类数的52.78%。按生态习性划分,定居性鱼类占总种数的88.89%,江湖洄游鱼类占总种数的11.11%;按栖息空间划分,底栖鱼类最多,占总种数的50.00%;按摄食类型划分,杂食性鱼类最多,占总种数的44.44%。鱼类优势种为鲇(Silurus asotus)、鲫(Carassius auratus)和贝氏歺又鱼(Hemiculter bleekeri)。渔获物中小型鱼类占据较大比例,大型鱼类比例偏低、规格偏小。Shannon-Weiner多样性指数、Margalef丰富度指数、Simpson优势度指数和Pielou指数均值分别为2.114、3.476、0.248和0.670。与历史资料相比较,鱼类优势种的数量占比降低,群落多样性、丰富度较高,均匀度较为稳定,但个体小型化现象依然存在,渔业资源仍有衰退趋势。建议强化禁渔措施,确保安庆江段渔业资源的可持续利用。     

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.     

Metabolic responses of matrinxã, Brycon amazonicus (Spix & Agassiz, 1829), exposed to environmental nitrite

Nitrite is usually found in aquatic environments where nitrification process occurs. This ion can cause several injuries to aquatic species, particularly fish. Nitrite reacts with haemoglobin yielding the non‐functional methaemoglobin, which leads to many physiological consequences such as functional anaemia and supposed hypoxia. Metabolism of the freshwater teleost matrinxã, Brycon amazonicus, exposed to environmental 0.6 mg L^?1 of nitrite N‐NO₂^? for 96 h was studied, and the fermentative/oxidative preference was gauged. Concentrations of glycogen, glucose, lactate, pyruvate and ammonia, plus the activities of lactate, glutamate and malate dehydrogenase were assayed. The exposure resulted in a metabolic profile that allowed inferring the continuity of oxidative metabolism. Catabolism of amino acids prevailed or was apparently exacerbated by inferred branchial injury and consequent impairment of nitrogen excretion. Moreover, the studied enzymes glutamate dehydrogenase, lactate dehydrogenase and malate dehydrogenase from brain and heart were little affected by nitrite. The expected fermentative metabolism due to the high methaemoglobin formation was not observed.