鱼类麻醉研究综述

为提高四川华吸鳅 (Sinogastromyzon szechuanensis) 生产选育与运输中的成活率,文章采用密闭静水法,研究了在水温 (18±0.5) ℃下不同质量浓度MS-222和丁香酚对体质量为 (2.029±0.26) g的四川华吸鳅的麻醉效果,探讨了MS-222和丁香酚这2种麻醉剂对其耗氧率、排氨率及氧氮比 (Oxygen-nitrogen ratio, O/N) 的影响。结果显示,1.5 mg·L⁻¹的MS-222或24 mg·L⁻¹的丁香酚可显著降低四川华吸鳅的耗氧率和排氨率 (P<0.05),耗氧率和排氨率均随MS-222浓度升高而降低,随丁香酚浓度升高而先升后降。在这2种麻醉剂胁迫下,当水温为14~26 ℃时,四川华吸鳅的耗氧率和O/N 均随温度的升高而上升,O/N为8.0−19.4,不同温度组间的耗氧率和排氨率差异极显著 (P<0.01)。结果表明,MS-222质量浓度为1.5 mg·L⁻¹或丁香酚质量浓度为24 mg·L⁻¹时可使四川华吸鳅进入麻醉剂Ⅱ期 (镇静期),可推荐为活鱼运输麻醉剂量,且以低温为宜。

     

Efficacy of tricaine methanesulphonate and clove oil as anaesthetics for juvenile cobia Rachycentron canadum

Six experiments were designed to determine the optimal anaesthetic dosage of tricaine methanesulphonate (TMS) and clove oil that could be used safely on juvenile cobia Rachycentron canadum of two sizes [G1=4.9±0.8 g; G2=13.9±3.1 g]. We documented the stage of anaesthesia and the acute toxicity as 96 h LC₅₀ (lethal concentration 50% population) at various exposure times of the two anaesthetics. At 10 min induction time, the TMS 96 h LC₅₀ was 93.9 mg L⁻¹ in G1 and 97.0 mg L⁻¹ in G2. Compared with clove oil, the 96 h LC₅₀ was 60.0 mg L⁻¹ in G1 and 69.8 mg L⁻¹ in G2. The difference between the two groups (G1, G2) did not influence anaesthesia safety ( P >0.05). Rachycentron canadum achieved stage 3 anaesthesia more rapidly at a lower clove oil concentration level (40 mg L⁻¹, 10 min) than TMS (60 mg L⁻¹, 10 min), but the recovery period of clove oil, was significantly longer. Clove oil was the most effective in reducing the short-term stress induced by routine biometry (20 mg L⁻¹, 10 min) and also by transporting (1 mg L⁻¹, 8 h). Whereas, for long-term exposure, 40 mg L⁻¹ TMS was found to be safe.     

Effects of clove oil and MS-222 on blood hormone profiles in rainbow trout Oncorhynchus mykiss, Walbaum

Clove oil has been demonstrated to be an effective, inexpensive anaesthetic and euthanizing agent for a number of fish species, including rainbow trout, used in aquaculture and fisheries research. However, the potential for clove oil to cause perturbations in important plasma hormone concentrations has not been investigated. The effect of anaesthesia and euthanasia in trout with eugenol (the active ingredient in clove oil) on plasma cortisol, glucose, growth hormone (GH) and two thyroid hormones [tri‐iodothyronine (T₃) and thyroxine (T₄)] was compared with tricaine methanesulfonate (MS‐222) anaesthesia, and stunning by cranial concussion in two experiments. Effects on blood chemistry were different when comparing the particular anaesthetic method being used. Stunning fish significantly increased plasma cortisol and glucose levels (both P<0.05), while euthanizing fish using either clove oil or MS‐222 had no effect on these hormone levels. In contrast, the levels of GH, T₃ and T₄ hormones were unaffected regardless of whether fish were euthanized by stunning, MS‐222 or clove oil. Variation in effects between hormones were observed using clove oil eugenol. In fish sampled 10 min after anaesthetizing with 150 mg L^?1 of eugenol, cortisol levels were significantly decreased (P<0.03), while there were no differences in either glucose or GH levels. Tri‐iodothyronine and T₄ also showed significantly elevated levels (P<0.05) after 10‐min exposure to eugenol. These results highlight the importance of investigating the potential effects of any new anaesthetic or euthanizing compounds on blood plasma parameters, prior to using them in a research setting, or when comparing results to other studies which have utilized alternative anaesthetic compounds.     

Identification of bacteria from the normal flora of perch, Perca fluviatilis L., and evaluation of their inhibitory potential towards Aeromonas species

Pathogenic Aeromonas sobria has been identified as a causative agent of ulcerative disease in farmed European perch, Perca fluviatilis L. To study the effect of the normal intestinal bacterial flora of perch against A. sobria, we sampled 193 bacterial isolates from the perch digestive tract. The isolates were identified by sequence analysis of the 16S rRNA gene and their inhibitory potential against A. sobria was evaluated in vitro. Nineteen of the strains isolated showed inhibition and were also tested against other aeromonad and non-aeromonad fish pathogens including Yersinia ruckeri and Vibrio anguillarum. Isolates showing inhibition were primarily Pseudomonas spp.; however, inhibitory Shewanella spp., and Delftia sp. were also identified. A Pseudomonas chlororaphis isolate showed inhibition against all fish pathogens tested.     

Effects of salinity on growth and mortality of migratory and resident forms of Eurasian perch in the Baltic Sea

Abstract – In the coastal areas of the Baltic Sea, there are two forms of perch (Perca fluviatilis). One of the forms is migratory and spawns in streams entering the Baltic Sea. The other form is resident and spawns in brackish water. Both forms utilise the coastal habitat for foraging. We examined the spawning success of the two forms in fresh and brackish water (7‰, equal to salinity in the south Baltic Sea). The experiments showed that hatching success was equally high in freshwater and in brackish water despite female origin. The survival of yellow‐sac and free swimming fry was significantly reduced in brackish water, which was independent if the fish was of migratory or brackish resident origin. Further, growth rate of perch fry was severely reduced in brackish water. The results indicate that perch has not developed any tolerance to brackish water in the young life stages. The migratory life strategy of perch can thus be explained by higher survival of fry in freshwater.     

Salinity tolerance of cultured Eurasian perch, Perca fluviatilis L.: Effects on growth and on survival as a function of temperature

Eurasian perch is generally only considered to be a candidate for freshwater aquaculture even though wild populations are found in estuarine and brackish water habitats. Little knowledge exists on two issues a) the effect of temperature on the salinity tolerance of perch and b) the long-term effects of brackish water on their overall growth performance. The present study addresses these two questions.

Firstly, the effect of temperature (12, 15, 20 and 25°C) on perch survival of a salinity challenge at either 13 or 18‰ was determined. Survival was unaffected by 13‰ at the two lowest temperatures whereas higher temperature and higher salinities had a dramatic detrimental effect (at 25°C, 50% mortality was reach at 62h and 39h for 13‰ and 18‰, respectively). Secondly, we examined the effect of salinity on growth, which was assessed by measuring standard length and body weight at regular intervals for 130days. In addition, Specific growth rate (SGR), Fulton's condition factor (K) and food conversion ratio (FCR) were also calculated as was the effect of salinity on plasma osmolality, blood ion content (Na⁺, Cl⁻, K⁺) and muscle water content at the termination of the experiment. The optimum growth for this study was seen in the lowest salinities at 0 and 4‰. Surprisingly, even small increases in salinity were detrimental to perch growth. At 10‰, growth in terms of body weight was reduced by about 50% after 130days compared to perch reared in freshwater.

Interest in brackish water production of perch would be most likely served best by selecting a strain of perch that is adapted to saline conditions, as found in the lower Baltic region. Further studies are required to understand the potential for brackish water perch production.     

Effects of intensive fishing on the perch population in a large oligotrophic lake in eastern Finland

The perch population in Lake Höytiäinen was intensively fished to reduce the density of the population and hence also the predation pressure by perch on vendace larvae. A hypothesis suggests that this predation can prevent recovery of commercially important vendace stock from a state of low-density. In the 1990s the density of the perch population in Lake Höytiäinen has increased, while the vendace stock has been sparse. Intensive fishing was conducted by professional fishermen with a paired bottom trawl, seine net, hoop net and small fish traps and by recreational fishermen with small fish traps. The size of perch population during the intensive fishing period was studied by test fishing with multi-mesh gillnets and the Leslie method in which trawl YPUE was regressed on the cumulative yield. The results suggest that the population size clearly diminished in the area where the fishing pressure was strongest. YPUE of test fishing decreased ca. 30% whereas the Leslie method gave almost a decrease twice as large as that of the former. Mean weight of perch increased in the trawl and test fishing catches during the intensive fishing period. The most effective fishing gear was trawl (62% of the total yield), but importance of trap net fishing by recreational fishermen was also high as they caught 22% of the total yield.     

Anaesthetic properties of Propiscin (Etomidaat) and 2-phenoxyethanol in the common carp (Cyprinus carpio L.), neural and behavioural measures

The objective of the study was to evaluate the anaesthetic effects of Propiscin (2% etomidate) and 2-phenoxyethanol on common carp ( Cyprinus carpio L.) by observing neural and behavioural measures. When exposed to the anaesthetic agent, the carp lost equilibrium after approximately 90 s of exposure. They did not breathe and the controls did not respond to tail pinch or prick or 6 V at the skin of the upper jaw. A shift to lower frequencies on the electroencephalogram (EEG) and computing fast Fourier transformation was observed when exposed to water containing Propiscin or 2-phenoxyethanol. Heart rate was reduced after placement in the water containing an anaesthetic agent. It may be concluded from our results that common carp were immobilized and sedated, when exposed to water containing 2 mL L⁻¹ Propiscin and immobilized and anaesthetized in water containing 0.5 mL L⁻¹ 2-phenoxyethanol. In addition, the use of EEG provides for a sound assessment of exposure of carp to these anaesthetics.     

The effect of depth on the interaction between perch (Perca fluviatilis) and minnow (Phoxinus phoxinus)

We tested the hypothesis that small fishes avoid piscivores by increasing their use of shallow water areas, thereby reducing the capture success of the piscivore. Experiments were conducted in 600-1 aquaria, using perch (Perca fluviatilis) as the piscivore and minnow (Phoxinus phoxinus) as the prey. Two size classes of minnows, presented alone and together, were placed together with perch in aquaria with and without shallow water areas. The capture success of perch and use of depth by minnows changed as predicted by our hypothesis. In addition, we observed a decrease in the shoal size of minnows when perch were present. Perch selected large minnows over small minnows when both size classes were present, probably because large minnows were a more energetically profitable prey size.     

Efficacy and effects of clove oil and MS‐222 on the immune‐biochemical responses of juvenile rohu Labeo rohita

The present study determined the effective concentrations of clove oil and MS‐222 in juvenile rohu Labeo rohita for quick induction and recovery. The immune‐biochemical responses due to 0, 1 and 24 hr exposure to those anaesthetics were also evaluated. Of four concentrations of the anaesthetics examined, the lowest effective concentration of clove oil and MS‐222 were 50 µl/L and 125 mg/L respectively. Clove oil and MS‐222 significantly increased the myeloperoxidase, total protein and alkaline phosphatase activity at some of the holding durations. However, superoxide anion production (after 0 and 1 hr) and antiprotease activity (after 24 hr) were significantly reduced in fish exposed to clove oil. Serum glucose content was significantly elevated in the MS‐222‐treated group. Furthermore, the clove oil‐treated group showed significantly higher levels of serum Na⁺ and K⁺, while the aspartate and alanine aminotransferase activities were significantly enhanced in the MS‐222 group. The use of both clove oil and MS‐222 is advised as an anaesthetic agent for rohu with a bias towards clove oil, considering its economic and operational feasibility.     

Long-term effects and interactions of dietary vitamins C and E on growth and reproduction of yellow perch, Perca flavescens

This study was conducted to examine the effects of dietary vitamin C and/or E and their interaction on growth and reproductive performance in yellow perch. Yellow perch juveniles were divided into four treatments with triplicate groups and fed with one of four semi-purified diets for 32 weeks. The experimental diets were formulated to contain no or high vitamin E levels (160 mg/kg) without or with vitamin C supplementation (250 mg/kg) designated as diets −C−E, −C+E, +C−E, or +C+E, respectively. The growth rates and survival of yellow perch fed with +C−E and +C+E diets were significantly higher than the fish fed with −C−E diet. Total- and dehydro-ascorbate concentrations in liver and testis increased in response to its dietary supplementation. The -tocopherol concentration in sperm was significantly affected by dietary supplementation of vitamin C. Gonadosomatic index of males was lower in the fish fed with −C−E diet compared to that of fish fed with other diets. Hatching rates of embryos obtained from testing sperm viability was significantly improved in fish fed with the diets sufficient in vitamin C (82±7%) compared to the fish fed with the −C−E diet (59±7). This study indicates that supplementation of dietary vitamin C and E increase growth rate, and semen quality can be improved by dietary vitamin C supplementation within one maturation cycle, and vitamin C may spare sperm vitamin E depending on vitamin E stores in tissues.     

Simultaneous effect of sex and dose on efficacy of clove oil,tricaine methanesulfonate, 2‐phenoxyethanol and propofol as anaesthetics in guppies,Poecilia reticulata (Peters)

We studied the simultaneous effect of sex and dose on anaesthesia efficacy to estimate, if possible, the lowest effective dose (LED) for clove oil, tricaine methanesulphonate (MS‐222), 2‐phenoxyethanol (2‐PE) and propofol in mature guppies. LED is the lowest dose needed to reach A5 stage in a mean time of 3 min, with mean recovery (R5) time of 5 min. We used four doses/anaesthetic: 25, 50, 75 and 100 mg/L for clove oil; 120,140,160 and 180 mg/L for MS‐222; 800, 1,000, 1,200 and 1,400 mg/L for 2‐PE, and 7.50, 8.25, 10.00 and 11.25 mg/L for propofol. Each dose was tested on 10 females and 10 males. Morbidity, mortality and behavioural changes were checked on two control groups (10 males and 10 females/group). Sedation (A3), A5 and R5 times were recorded. Significant interactive effect dose*sex on A5 time was found for each anaesthetic agent (p_dose*sex < .05). Except for MS‐222 (p_dose*sex = .284), significant interactive effect dose * sex on R5 time was found (p_dose*sex < .05). A5 time in females tended to be greater than in males, but, in general, R5 times were longer in males. Body size differences between males and females could explain these differences in MS‐222 on A5 time and for clove oil, 2‐PE and propofol on R5 time. No dose simultaneous meet LED′s conditions relating to both A5 and R5 times; therefore the lowest doses inducing A5 in a mean time of 3 min could be a safe guideline for anaesthetic procedure in both male and females.     

饲料脂肪水平对锦鲤幼鱼生长和血液生化指标的影响

本实验以初始体重为(5.85±0.19)g红白锦鲤(Cyprinus carpio L)幼鱼为实验对象,研究在螺旋藻添加量为12%时,饲料脂肪水平对锦鲤生长、饲料表观消化率、肠道消化酶和血液生化指标的影响。实验设5.36%、7.74%、10.52%、12.85%、15.45%5个脂肪梯度,每组设3个重复,每个重复10尾鱼,表观饱食投喂60 d。结果显示:脂肪水平为5.36%～10.52%,锦鲤增重率(BWG)、特定生长率(SGR)随脂肪水平的升高而升高,均在脂肪水平为10.52%时,达到最大值。实验鱼血清谷丙转氨酶(ALT)随脂肪添加比例呈现先下降再升高的趋势,脂肪水平为12.85%后,血清ALT显著升高(P<0.05),脂肪水平为15.45%时,血清GLU浓度显著升高(P<0.05),而甘油三酯(TG)、总胆固醇(CHOL)随脂肪水平的升高各实验组间无显著性差异(P>0.05)。结果表明,螺旋藻添加量一定时,锦鲤适宜脂肪添加水平为10.52%。     

Effects of water temperature and body weight on anaesthetic efficiency in marbled rabbitfish (Siganus rivulatus)

The effects of four anaesthetic agents, tricaine methanesulphonate (MS‐222) (112.5 mg L^?1), 2‐phenoxyethanol (400 μL L^?1), clove oil (70 mg L^?1) and benzocaine (65 mg L^?1) on juvenile marbled spinefoot (Siganus rivulatus) of three mean body weights (7.3 g, 19.1 g, 55.5 g) and at three temperatures (20, 25, 30°C) were evaluated. In addition, the relationship between body lipid content and efficacy of the four anaesthetic agents was evaluated in juvenile S. rivulatus. Times necessary for induction and recovery were recorded. Significant effects of temperature on induction and recovery times were observed. Induction and recovery times decreased with increasing water temperature. No uniform relationship between body weight of juvenile marbled spinefoot and anaesthetic efficacy was observed. Body fat content was positively correlated with induction time only when MS‐222 was used but did not affect induction times of fish exposed to 2‐phenoxyethanol, clove oil or benzocaine. Recovery times were generally longer for all fish containing more body fat. Results of the study show that anaesthetic efficiency increases with increasing water temperature but is not strongly affected by body weight for juvenile marbled spinefoot. In addition, body fat in fish affected the efficacy of the various anaesthetic agents tested in this study, generally slowing down recovery.     

Comparison of the effects of six stunning/killing procedures on flesh quality of sea bass (Dicentrarchus labrax,Linnaeus 1758) and evaluation of clove oil anaesthesia followed by chilling on ice/water slurry for potential implementation in aquaculture

The effects of different stunning/killing procedures on flesh quality of European sea bass were investigated: (1) anaesthesia with clove oil, (2) anaesthesia with 2‐phenoxyethanol, (3) percussive stunning, (4) immersion in ice/water slurry, (5) chilling on ice and (6) anaesthesia with clove oil followed by immersion in ice/water slurry. Muscle pH values were significantly lower in sea bass anaesthetized or stunned by a blow to the head compared with fish immersed in ice/water slurry, chilled on ice or immersed in ice/water slurry after clove oil anaesthesia. Lightness was highest in sea bass anaesthetized by 2‐phenoxyethanol or percussively stunned and lowest in ice‐chilled fish. Redness and yellowness were highest in fish chilled on ice and lowest in fish anaesthetized with clove oil. Liquid loss, fat loss and shear values were not significantly different among the procedures. In general, lipid oxidation values during refrigerated or frozen storage did not significantly differ among treatment groups. Combination of clove oil anaesthesia followed by chilling on ice/water slurry appears to improve both flesh quality and welfare of sea bass, although the implementation of further studies is warranted to consolidate this finding.     

Comparison of L‐lysine·HCl and L‐lysine sulphate in the feed of Penaeus monodon and re‐evaluation of dietary lysine requirement for P. monodon

Two trials were conducted to compare L‐lysine HCl and L‐lysine sulphate regarding its availability to Penaeus monodon, and further evaluate the optimum dietary lysine requirement. In experiment 1, five experimental diets were formulated (D1, D2, D3, D4 and D5), a basal diet (D1), aimed at a low‐lysine concentration (2.22% dry matter), with lysine concentration of the other four diets increasing in two 0.25% L‐lysine intervals from either L‐lysine HCl (D2 and D3) or L‐lysine sulphate (D4 and D5). Each diet was fed at a restricted rate to three groups of 40 shrimp for 74 days. The highest values of growth performance (weight gain, WG; specific growth rate, SGR) and survival were observed with shrimp fed the L‐lysine HCl diet. Feed efficiency (FE) of shrimp fed D2 was significantly higher than that of shrimp fed D1 and D5 (P < 0.05), but without significant difference with shrimp fed D3 and D4 (P > 0.05). In experiment 2, six diets (d1, d2, d3, d4, d5 and d6) were formulated with six graded levels of lysine (2.21%, 2.41%, 2.59%, 2.87%, 3.11% and 3.29% of diet). Each diet was randomly assigned to triplicate groups of 40 shrimp for 74 days. WG, SGR and survival increased increasing levels of lysine up to 2.41% of diet and reached an apparent plateau. Broken‐line model analysis on WG and SGR indicated that the optimum dietary lysine level for optimal growth of shrimp was 2.37% of diet, corresponding to 5.78% of dietary protein. In conclusion, results of this trial suggest that L‐lysine HCl is superior to L‐lysine sulphate when fed to Penaeus monodon and optimal growth can be obtained at lysine levels corresponding to 2.37% of diet, or 5.78% of dietary protein in this specie.     

Cascading effects of introduced Nile perch (Lates niloticus) on the foraging ecology of Nile tilapia (Oreochromis niloticus)

Abstract –  Nile tilapia ( Oreochromis niloticus L.) is the dominant of the introduced tilapiines in many East African lakes and has flourished in the presence of introduced Nile perch ( Lates niloticus L.). We explored the hypothesis that O. niloticus exhibits increased omnivory in response to a decline in abundance of haplochromine cichlids. First, we quantified variation in habitat use and diet of O. niloticus in Lake Nabugabo, Uganda. Second, we compared the diet of O. niloticus in lakes with (Nabugabo, Victoria) and without (Mburo, Wamala, Nyamusingiri, Kyasanduka) introduced Nile perch. In Lake Nabugabo, a higher level of phytoplanktivory was observed in small juveniles than in larger fish and in wetland ecotone areas where haplochromines were most abundant. An omnivorous diet dominated by detritus and invertebrates was recorded for O. niloticus in lakes Nabugabo and Victoria, while a predominantly herbivorous diet was characteristic of O. niloticus in lakes without Nile perch. Availability of a broad food base in lakes where inshore insectivores have been reduced may explain the increased omnivory recorded in lakes Nabugabo and Victoria.     

Comparison of effects of dietary‐specific fatty acids on growth and lipid metabolism in Nile tilapia

The dominant fatty acids (FAs) in oils are often used to explain different nutritional effects of dietary oils in fish. However, the amounts of dominant FAs among oils are different, and the nutritional roles of these important FAs in fish have not been precisely compared at similar levels in feeding trials. In the present study, different amounts of palmitic acid were added to safflower oil (SO), olive oil (OO) and fish oil (FO) to obtain comparable amounts (about 550 g/kg of total FAs) of 18:2n‐6, 18:1n‐9 and 20:5n‐3 + 22:6n‐3 and subsequently fed to Nile tilapia (11.1 ± 0.01 g) for 8 weeks. The results showed similar growth among groups but FO group obtained lower fat deposition, serum ALT and AST activities, compared to OO. Lipogenesis‐related gene expressions were higher in OO group than FO group in liver, muscle and adipose tissue, but there were only few differences in these genes between SO and FO groups. Lipid catabolism genes in FO group were higher than OO and SO groups in adipose tissue, but not in muscle, and the significantly higher expressions of CPT1b and PPARα were only observed in liver. Overall, dietary 18:2n‐6, 20:5n‐3 and 22:6n‐3 were beneficial to normal growth and lipid metabolism, whereas high amount of 18:1n‐9 induced lipid deposition and liver damage in Nile tilapia.     

中草药添加剂对鲁氏耶尔森菌感染虹鳟血液生化指标的影响

为研究复方中草药对鲁氏耶尔森菌(Yersinia ruckeri)感染虹鳟(Oncorhynchus mykiss)后其血液生化指标的影响,在虹鳟饲料中分别添加两种复方中草药(复方1组、复方2组),持续投喂28 d。在第28天感染鲁氏耶尔森菌,检测感染后72 h的血清生化指标,并统计各组存活率。结果显示:复方中草药组对虹鳟增重无抑制作用。添加复方中草药可提高虹鳟感染鲁氏耶尔森菌后的存活率,其中复方2组的保护效果最好。感染72 h后,复方2组总蛋白、白蛋白、球蛋白、甘油三酯、总胆固醇含量和碱性磷酸酶活性均高于对照组。复方2组谷丙转氨酶、谷草转氨酶活性低于对照组,乳酸脱氢酶活性显著低于对照组。复方1组和复方2组尿酸含量显著低于对照组。复方中草药组总胆红素、尿素氮、肌酐和血糖含量与对照组相比无显著性差异。结果表明,添加复方中草药能提高鲁氏耶尔森菌感染后虹鳟的存活率,其中复方2组的保护效果最好。