新疆乌伦古湖河鲈食性变化的研究

2007年4月25～30日,对乌伦古湖河鲈的食性进行了调查研究.与1987年比较乌伦古湖河鲈食物组成发生了明显的变化;主要食物由20年前的摇蚊幼虫变为易得的池沼公鱼,适口饵料生物的减少使得河鲈选择了替代食物.推断了乌伦古湖河鲈食物的制约是影响种群补充的重要原因.     

Digestibility of microbial and mussel meal for Arctic charr (Salvelinus alpinus) and Eurasian perch (Perca fluviatilis)

Apparent digestibility coefficients (ADCs) for four protein‐rich alternative feed ingredients, intact baker's yeast (Saccharomyces cerevisiae), extracted baker's yeast (S. cerevisiae), zygomycetes (Rhizopus oryzae) and blue mussel (Mytilus edulis), were determined for Arctic charr (Salvelinus alpinus) and Eurasian perch (Perca fluviatilis). Diets contained 30% of test ingredients, and ADCs were compared to a reference diet containing fish meal. For Arctic charr, ADCs for dry matter (DM, 71–99%), sum of amino acids (SAA, 84–99%) and gross energy (70–99%) were significantly lower for intact S. cerevisiae than for extracted S. cerevisiae, R. oryzae and M. edulis. The ADCs for the indispensable amino acids (IAA) in Arctic charr varied between 84% and 99%. Significant differences were found in ADCs for IAA between the test ingredients for Arctic charr, with higher values for extracted S. cerevisiae and M. edulis. The ADCs in Eurasian perch varied between 83% and 95% for DM, 89% and 98% for CP, 92% and 100% for SAA, 81% and 96% for gross energy. No significant differences were found for ADCs between the test ingredients in Eurasian perch, indicating a species effect on digestibility. Furthermore, the absence of intact cell walls had a positive effect on digestibility of S. cerevisiae for Arctic charr.     

Effect of Culture Temperature on Growth, Survival, and Biochemical Composition of Yellow Perch Perca fiavescens

Juvenile yellow perch Perca fiavescens were evaluated under controlled conditions in tanks for 13 wk to determine the effect of temperature on growth to advanced sizes under intensive culture conditions. Yellow perch weighing 6.6 ± 1.5 g were stocked into nine 4,755-L tanks at 131 fish/m³ (625 perch/tank). There were three replicate tanks per temperature (20, 24, and 28 C). Perch were fed to apparent satiation twice daily using a 45% crude protein diet with 16% crude fat. After 93 d the perch in the 24 C treatment were significantly larger ( P < 0.05) than those in the 20 C and 28 C treatments, which were not significantly different (P < 0.05) from each other. Yellow perch raised at 28 C had significantly higher ( P < 0.05) feed conversion ratios and significantly lower ( P < 0.05) survival and net protein utilization than perch raised at 20 C or 24 C. Whole body moisture was significantly higher in ( P < 0.05) yellow perch raised at 20 C which also had significantly higher levels of arachidonic acid (20:4 n-6) and docosohexaenoic acid (22:6 n-3). The ratio of palmitic acid (16:0) and palmitoleic acid (16:1 n-6) had a positive correlation ( P < 0.05) with culture temperature. These data indicate that 24 C may be an optimum temperature for yellow perch. At 20 C survival and feed conversion are good but growth rates are reduced. Temperatures near 28 C appear sufficient to represent chronic stress conditions.     

The energy requirements of Eurasian perch (Perca fluviatilis L.) in intensive culture

Fish feed constitutes one of the largest costs in aquaculture, therefore inefficient feed management will have a negative impact on fish farm economics. Eurasian perch (Perca fluviatilis L.) is a relatively new candidate for freshwater aquaculture, however little is known about the energy requirements of this species. The aim of this study was to develop an energy requirement model for intensive culture of Eurasian perch reared at rational temperatures. Data on growth (the thermal unit growth coefficient, TGC, ³√g · (°C · days)^?1) and digestible energy need (DEN, kJ DE · g^?1) of Eurasian perch at a size range of 20–180 g and at temperatures of 17–23 °C were used. Regression analysis revealed that both TGC and DEN were affected significantly by fish size (P < 0.001) but not by temperature (P > 0.05). Two models including body size of the fish were developed: (i) an inverse TGC model for evaluation of the daily theoretical weight increment (TWi, g · day^?1) and (ii) a linear DEN model. The TGC model was validated by comparing theoretical data with data obtained from a commercial growth trial. By combining the TWi and the DEN, a model describing the daily theoretical energy requirement (TER, kJ · day^?1) at different temperatures and for Eurasian perch of different sizes was successfully developed.     

The Spawning of Perch (Perca fluviatilis L.) in Loch Leven, Kinross, Scotland

Investigations were carried out in 1979 and 1980 into the location of spawning grounds of perch in Loch Leven, the comparative intensity of their use and the duration of the spawning period. Spawning was found to take place in depths of 1–5 m and there was an indication that depths around 3 m are preferred. Silt and mud apparently inhibit spawning on exposed shores down to 2.5 m although natural shelter probably ameliorates this. Macrophytic vegetation is rarely present at the preferred depths, therefore, artefacts and artificial substrates must be most frequently used. Spawning started about 25 April in a ‘mild’ spring and about 9 May in a ‘cold’ spring. The duration of the spawning period was 4–5 weeks. A double peak in spawning intensity was found in 1979 and, if valid, could indicate a division of spawning fish into two groups, possibly by age as the peaks were not associated with the location of spawning sites. Although spawning tended to be more intense on the southern shore and around one of the islands almost any part of the loch down to 5 m may be used.     

Effects of dietary fat levels on growth, feed efficiency and biochemical compositions of Eurasian perch Perca fluviatilis

A feeding experiment was conducted for 10 weeks with Eurasian perchPerca fluviatilis juveniles (33.1–35.9ginitial body weight) using three dietary fat levels (11.7, 15 and 19.3%). Theresults showed that increasing dietary fat content increased growth, feedefficiency and protein utilization of perch (P < 0.05) but did not affectmortality. Lipid analysis showed that the composition of some perch tissueswerealso significantly affected by increasing dietary fat content, with an increaseof lipid deposition in the viscera (from 64.9% in fish fed 11.7 % fat to 78.8%in fish fed 19.3% fat) and liver (from 12.4 to 23.8%) (P < 0.05), while themuscle composition was not affected by the dietary treament. Highdocosahexaenoic acid (22:6n-3, DHA) and high docosahexaenoicacid/eicosapentoenoic acid (20:5n-3, EPA) ratios were found in the liver andmuscle lipids as compared to the dietary fatty acid compositions, suggestingthat Eurasian perch might possess a high capability of converting the longchainhighly unsaturated fatty acids, especially DHA from its dietary precursors.     

Effects of dietary fat levels on growth, feed efficiency and biochemical compositions of Eurasian perch Perca fluviatilis

A feeding experiment was conducted for 10 weeks with Eurasian perchPerca fluviatilis juveniles (33.1–35.9ginitial body weight) using three dietary fat levels (11.7, 15 and 19.3%). Theresults showed that increasing dietary fat content increased growth, feedefficiency and protein utilization of perch (P < 0.05) but did not affectmortality. Lipid analysis showed that the composition of some perch tissueswerealso significantly affected by increasing dietary fat content, with an increaseof lipid deposition in the viscera (from 64.9% in fish fed 11.7 % fat to 78.8%in fish fed 19.3% fat) and liver (from 12.4 to 23.8%) (P < 0.05), while themuscle composition was not affected by the dietary treament. Highdocosahexaenoic acid (22:6n-3, DHA) and high docosahexaenoicacid/eicosapentoenoic acid (20:5n-3, EPA) ratios were found in the liver andmuscle lipids as compared to the dietary fatty acid compositions, suggestingthat Eurasian perch might possess a high capability of converting the longchainhighly unsaturated fatty acids, especially DHA from its dietary precursors.     

Reproductive cycle and plasma levels of steroids in male Eurasian perch Perca fluviatilis

From April 1995 to April 1996, the annual reproductive cycle of male Eurasian perch Perca fluviatilis was studied at the Lindre Center (Moselle, France). At monthly intervals, five males (mean body weight of 133 ± 43 g and total length of 175 ± 9 mm) were caught. From sampled organs, the gonadosomatic (GSI), hepatosomatic (HSI) and viscerosomatic indexes (VSI) were calculated and plasma testosterone (T) and 11-ketotestosterone (11KT) levels were measured. After the spawning period in mid-April, GSI and HSI dropped and VSI increased to 3.8 ± 0.1 %. In September, GSI reached its maximum (8.5 ± 1.8 %). At this time, spermatocytes, spermatids and spermatozoa were abundant, whereas in June only spermatogonia were observed. During winter, GSI was stable at approximately 5 %, HSI reached its maximum (1.9 ± 0.3 %) and VSI was low (2.6 ± 0.2 %). From April to November 1995, plasma T and 11KT concentrations were low (< 0.5 ng·mL^–1). Plasma T levels increased significantly in December and reached peak levels (12.3 ± 2.1 ng·mL^–1) in January, then decreased in February and increased again until spawning in April (6.8 ± 2.1 ng·mL^–1). This second elevation could be related to the beginning of a new spermatogenic cycle. Plasma levels of 11KT increased significantly from October to February 1996 (4.9 ± 1.1 ng·mL^–1). From February to the spawning period (April 1996), plasma 11KT decreased significantly, but values were significantly higher than those measured in fall. Males were spermiating from January to spawning in April.     

Dynamics of total lipids and fatty acids during embryogenesis and larval development of Eurasian perch (Perca fluviatilis)

Total lipid and fatty acid compositions were determined during embryogenesis and larval development in Eurasian perch (Perca fluviatilis). During embryonic development, perch did not catabolize lipids and fatty acids as an energy source. However, during larval development, there was an exponential relationship between the decrease in total lipids and the duration of starving (r²=0.9957) and feeding (r²=1). The duration of the starving period (10 days post hatching) was shorter than the feeding period (35 days post hatching). In both starved and fed larvae, there is an apparent preference in utilization of polyunsaturated fatty acids followed by monounsaturated fatty acids. Saturated fatty acids were utilized by neither fed perch larvae nor by starved perch larvae. In starved larvae, palmitoleic 16:1(n-7) and oleic 18:1(n-9) acids were the preferentially monounsaturated fatty acids catabolized and their contribution as energy source from total fatty acids catabolized over the first week was 37.6%. In fed larvae, these 2 nutrients were also the most monounsaturated fatty acids utilized as energy source and possibly also as precursors for others monounsaturated fatty acids biosynthesis. During the same period and among (n-6) polyunsaturated fatty acids, starved perch utilized less linoleic 18:2(n-6) and arachidonic 20:4(n-6) acids than fed larvae despite the fact that the starved perch were in more unfavorable nutritional conditions. In the case of (n-3) fatty acids, starved larvae utilized more linolenic acid 18:3(n-3) and less eicosapentaenoic 20:5(n-3) acid and docosahexaenoic 22:6(n-3) acid than fed perch. Starved larvae probably spared 20:5(n-3) and 22:6(n-3) for physiological functions.     

Growth of 0+ perch (Perca fluviatilis) predating on 0+ bream (Abramis brama)

Abstract – Larvae and juveniles of perch Perca fluviatilis and bream Abramis brama of Lake Speldrop, a highly eutrophicated gravel-pit lake in the floodplain of the Lower Rhine, were used in laboratory experiments to study predation of perch on bream. In the first series of experiments (control), 0+ perch of 30 mm total length (TL) did not prey on 0+ roach of about 24 mm TL. The perch fed only on zooplankton, resulting in low growth rates of 0.17 mm  ·  day⁻¹. In the second series of experiments, perch (30 mm TL) were combined with 0+ bream with an average TL of 14 and 19 mm at different ratios. As in the first series, even a nine-fold higher amount of zooplankton food had no significant influence on the growth rate of perch, regardless of the perch:bream ratio. At a perch: bream ratio of 7:1 and 4:4 all bream were eaten by the perch and restocked twice daily. At the end of the experiment, the TL of perch at a perch:bream ratio of 7:1 was significantly lower compared to a perch:bream ratio of 4:4 (mean growth rates at 7:1 of 0.16 mm  ·  day⁻¹ and at 4:4 of 0.35 mm  ·  day⁻¹). At the perch:bream ratio of 1:7, perch fed on bream in varying amounts, averaging between 3 and 12 bream per day and per individual. After 20 days, the final length of these fish was always significantly higher than the TL of perch at other perch:bream ratios and increased in correlation to number of bream eaten per day (mean growth rate 1.13 mm  ·  day⁻¹). The results are discussed with respect to the piscivore-dominated fish community of the eutrophied Lake Speldrop. ^Note     

Perch (Perca fluviatilis) as an indicator species for structural degradation in regulated rivers and canals in the lowlands of Germany

Abstract— Simple morphological characteristics and fish assemblage data were collected in representative numbers from 12 inland waterways in the northeastern lowlands of Germany between 1992 and 1995. Fish abundance data were pooled and classified into three main groups: perch Perca fluviatilis (L.), roach Rutilus rutilus (L.) and other species. Spearman rank correlations between fish abundance and type of embankment revealed that perch showed a statistically significant numerical dominance in waterways consisting predominately of an artificial shoreline, suggesting that perch may be used as an indicator of the structural degradation of watercourses.     

Rates of oxygen consumption and ammonia excretion of juvenile Eurasian perch Perca fluviatilis L.

The impact of feeding, fish size (body weight from 18.5 to 56.5 g) and water temperature (20 and 23 °C) on oxygen consumption (OC, mg O₂ kg^–1 h^–1) and ammonia excretion (AE, mg TAN kg^–1 h^–1) was studied in Eurasian perch held in recirculation systems. OC for both fed and feed-deprived (3 days) fish was higher at 23 °C (278.5 and 150.1 mg O₂ kg^–1 h^–1) than at 20 °C (249.3 and 135.0 mg O₂ kg^–1 h^–1; P < 0.01). AEs for both fed and feed-deprived fish were also significantly higher at 23 °C than at 20 °C (P < 0.001). Water temperature and fish size had a significant impact on the oxygen:feed ratio (OFR, kg O₂ kg^–1 feed fed day^–1) and ammonia:feed ratio (AFR, kg TAN kg^–1 feed fed day^–1; P < 0.001). Their average values at temperatures of 20 and 23 °C were 0.17 and 0.19 kg O₂ kg^–1 feed fed day^–1 and 0.009 and 0.011 kg TAN kg^–1 feed fed day^–1, respectively.     

Effects of Lighting Spectrum and Disturbance Level on the Growth and Stress Responses of Yellow Perch Perca flavescens

Abstract.— We evaluated the effects of different lighting spectra and routine disturbances on the growth and stress responses of yellow perch Perca, flavescens. Fish were reared in tanks under one of three different lighting spectra: blue (405–530 nm), red (600–750 nm). or full spectrum (380–750 nm). For each lighting spectrum, fish were reared under one of two disturbance levels: one in which the fish were exposed to 2–4 daily routine disturbances which typify intensive tank culture conditions (e.g., casting shadows over the tank, sham tank siphoning, and dissolved oxygen measurement: ‘disturbed’). or a second treatment in which such disturbances were minimized (‘undisturbed’). The fish were reared for 87 d under temperature, photoperiod. and feeding conditions near optimal for the growth of yellow perch. The cortisol stress response of the different fish groups was evaluated by measuring baseline serum cortisol levels on days 0, 1,3, and 21, and by measuring cortisol levels 30 min after the application of an acute handling stressor on days 0, 1, and 3. Treatment effects on growth were measured from days 21–86 of the study. On day 87, various organs and parameters were evaluated to compare the health and condition of fish reared under the different treatments. Disturbed fish gained less weight and length, and had a significantly lower condition factor than undisturbed fish. Additionally, the disturbed fish showed no signs of acclimation to the frequent disturbances. The fish under red and full spectrum light gained more length than those under blue light. Frequent disturbance had a greater negative effect on length gain in fish reared under red light than in those reared under the other light treatments. On day 21, but not on other days, baseline cortisol levels were higher in disturbed than in undisturbed fish. Undisturbed fish had higher levels of mesentery fat than disturbed fish. Our results demonstrate that yellow perch growth can be significantly affected by disturbance level and lighting conditions. These factors should be taken into consideration when developing culture strategies to maximize the growth of yellow perch reared under intensive culture conditions.     

Spawning site selection by Eurasian perch (Perca fluviatilis L.) in relation to temperature and wave exposure

Abstract –  The selection of spawning depth by Eurasian perch Perca fluviatilis was investigated in an experiment using artificial substrata in Lake Constance during the spawning season of 2007. The experiment compared spawning behaviour at substrata between 0.5 and 15 m depth at two sites exposed to different regimes of ship-generated wave action. The total abundance of egg ribbons did not differ significantly between the two sites, but the preferred spawning depth was deeper at the wave exposed site (5 m) compared to the sheltered site (2 m). While water temperatures could not account for the observations, differences in wave exposure may explain the different spawning depth preferences. At both sites, large egg ribbons were generally found in deeper water, and large egg ribbons occurred more frequently at the sheltered site. Because the egg ribbons of perch are likely to have a size-dependent susceptibility to hydrodynamic stress, large females may be expected to select deeper spawning locations where the effects of surface waves are considerably attenuated.     

Effects of probiotic bacteria on growth parameters and immune defence in Eurasian perch Perca fluviatilis L. larvae under intensive culture conditions

Two experiments were conducted to examine whether a mixture of bacteria composed of Bacillus licheniformis, Bacillus subtilis and Bacillus pumilus has a beneficial impact on survival, growth, lysozyme activity and total immunoglobulins (Ig) in perch larvae. In experiment 1, control fish were compared with fish receiving bacteria (4.93 × 10⁷ CFU L⁻¹ day⁻¹) through tank water or both through tank water and Artemia metanauplii enriched with two bacteria doses (2 × 10¹⁰ or 4 × 10¹⁰ CFU L⁻¹). Treatments were performed in 40 L triplicate tanks of 200 fish [initial body weight (IBW)=2.3 mg] each, placed in separated recirculating water systems. Experiment 2 evaluated the combining effects of bacteria feeding and densities (10 vs. 20 fish L⁻¹, IBW=9.5 mg). In both experiments, the bacteria added to live food or both live food and water induced higher growth rate at the highest dietary dose and this was associated with higher Ig levels on days 14 and 28. In experiment 2, higher survival was associated to lower type‐2 cannibalism (ingestion of whole prey) at the two dietary bacteria doses, and such positive effect was observed for fish fed bacteria at high density. Bacteria administration through water had no effect on growth and survival. In conclusion, the results show that high dietary concentrations of the mixture of bacteria used have potential stimulating impact on growth, survival, lysozyme activity and total Ig. But, further investigations are needed to demonstrate the optimal doses for emphasizing immune defence status.     

Intra-cohort cannibalism among larval stages of perch (Perca fluviatilis)

Cohorts of perch larvae, hatched within 24 h, developed into a bimodal body size distribution as early as 6 days after commencement of external food uptake. At this development stage, intra-cohort cannibalism occurred among larval perch individuals of larval stage V (body size: 10.5±0.26 mm, 95% c. l.) on smaller siblings. In experimental trials the consumption rate (C: no. of prey/predator·hour) increased exponentially with size of predatory perch (L: mm) and at 21°C was expressed by the relationship log C=3.406·log L-3.848 (n=10, r²=0.98, P<0.001). For predatory perch in larval stage V, consumption rate was reduced when Daphnia pulex were added, while not in later stages. Perch larvae experimentally forced to live as true piscivores without additional food items developed from stage V to stage IX (15.8±1.34 mm) within the same time as those fed on Daphnia alone, but with increased mortality.     

不同驯化方式对哲罗鱼仔、稚鱼生长和存活的影响

在水温8．9～14．2℃下,在平列糟（长3m,宽0．4m,高0．2m）中采用A、B和C组三种投喂方式驯养刚开口摄食、体质量0．129±0．07g的哲罗鱼（Huchotaimen）苗60d,以探讨驯化方式对哲罗鱼仔、稚鱼生长、存活和种群变异系数的影响：A组以浮游动物开口,投喂浮游动物3d,投喂水蚯蚓15d后,改投人工饲料;B组以水蚯蚓开121,投喂水蚯蚓15d后,改投人工饲料;C组直接以人工饲料开口。结果表明：C组体质量特定生长率（3．577±0．78％／d）,明显大于A组（3．132±0．87％／d）和B组（3．024±0．91）;A、B、C组的成活率分别为75．67％、74．87％和84．36％,C组明显大于A、B组;A、B和c组鱼体质量变异系数依次为21．47％、22．59％和11．32％,实验表明,直接以人工饲料开口是哲罗鱼规模化养殖中合理的驯化投喂模式。