首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
人工养殖条件下岩原鲤幼鱼排空率与摄食量   总被引:1,自引:0,他引:1  
在室内微流水养殖条件下,以水蚯蚓(Limnodrilus sp.)为饵料,应用现场胃含物法,研究岩原鲤[Procypris rabaudi(Tchang)]幼鱼的排空率和日摄食量。结果表明:岩原鲤幼鱼摄食强度具有明显的昼夜节律,呈现较典型的单峰分布特征,其摄食强度高峰时间在0:30到6:30;在实验水温18.6℃时,用湿重表示胃含物质量,线性、指数和平方根3种常用模型均可较好拟合岩原鲤幼鱼[体质量(3.30±0.94)g]的排空率实验数据(df=18,P<0.001),综合评价结果进一步表明,其中指数模型拟合度最好,所得模型为St=0.139e-0.169t(r2=0.952,P<0.001);同时得到岩原鲤幼鱼的排空率(以湿重计)为0.169 g/(100g.h)。实验得到养殖岩原鲤幼鱼的日摄食量(湿重)为24.91 g/(100g.d);应用Elliott-Persson模型评估得到自然环境中岩原鲤幼鱼日摄食量(以湿重计)Cd=14.309 g/(100g.d)。研究建立的岩原鲤幼鱼空消化道重(EDW)-体长(BL)-体质量(BW)经验关系式为EDW=0.24(BW/BL)1.547-0.139(n=83,r2=0.89)。研究表明,指数模型最适于描述岩原鲤幼鱼胃排空特征,Flliott-Persson模型在野外环境中岩原鲤幼鱼摄食评估上具有较大适用性。这些结果可为岩原鲤幼鱼摄食生态的定量研究及环境容纳量评估提供基础资料。  相似文献   

2.
Groups of 3–4 g African catfish (Clarias gariepinus Burchell, 1822; Family: Clariidae) were offered feeds of two types in three combinations: feed with a radio-opaque marker (Ballotini, 0.16–0.25 mm), feed without marker and a 50:50 mixture of marked and unmarked feeds. Stomach contents were estimated by X-radiography and gastrectomy just after meal termination and at different time intervals (4, 8, 12, 16, 20, 24, 32, 40 and 48 h). There were no significant differences among treatment groups confirming that there was no effect of the marker on feed preference and evacuation rate. Estimations of gastric evacuation rate calculated from gastrectomy and by X-ray sampling were not significantly different. Therefore, gastric evacuation rate of African catfish can be accurately estimated by feeding marked feed and then using X-radiography to monitor feed passage through the gut. © Rapid Science Ltd. 1998  相似文献   

3.
Threatened obligatory riverine fishes in human-modified Polish rivers   总被引:4,自引:0,他引:4  
Abstract – The fate of obligatory riverine fish species (rheophils), which are the objects of anglers' exploitation (chub – Leuciscus cephalus , nase – Chondrostoma nasus , barbel – Barbus barbus , gudgeon – Gobio gobio ), and brown trout ( Salmo trutta m. fario ) and grayling ( Thymallus thymallus ) (in the Gwda River basin only), were investigated in large alluvial rivers (Pilica and Warta) and in the medium-sized Gwda River basin. The Pilica (1973) and the Warta (1986–1987) were divided by large dams without fish ladders in their middle courses. The Gwda River was divided by only a few dams along its course, but its tributaries carrying pure water had numerous small dams that supplied water for fish farms. Other stresses influencing fish populations in these rivers were: pollution, overfishing, hydroelectric plants and bank revetments. Because the listed stresses occurred alternately and at various periods of time in these rivers, this enabled attributing the cause for extinction and reduction of the abundance and distribution. In the salmon Gwda River basin, a drastic decrease in spatial distribution and reduction of occurrence ranges of brown trout, grayling and barbel was evident in respect to the first study period (1980s) in the 1990s. In the large, alluvial Pilica River, nase, barbel and dace are on the edge of extinction and chub and gudgeon are vulnerable. In the Warta's tailwater, barbel is an extinct species, and chub, dace and gudgeon are vulnerable ones. In a site in the backwater, none of the above mentioned species became extinct, but their abundance and occurrence frequency decreased a bit in respect to the pre-impoundment period. Roach-generalist, which was used in this research as a "control" species, increased in abundance in all 3 rivers. These investigations univocally proved that the dams cause catastrophic stress for obligatory riverine species. NOTE  相似文献   

4.
5.
Approximately 5000 young of the year (0+) cyprinids comprising roach, chub, dace, minnow, bleak, bream, barbel and gudgeon were examined histologically for the presence of myxozoan infections. Thirteen myxozoans were identified to species, the majority being Myxobolus spp. In addition, two species of Myxidium and of Sphaerospora were recorded. All organs were examined, with the majority of infections being found in the gills, musculature and kidney. However, isolated spores were occasionally found in other tissues. Whilst roach contained the highest number of myxozoan species, it was chub that showed the greatest host response to sporogonic forms. Data are provided on spore morphology, pathogenic responses and tissue and host specificity of the myxozoans recorded.  相似文献   

6.
Abstract –  We examined the diel feeding pattern, gastric evacuation and daily ration of a lentic, endemic Tasmanian galaxiid fish, Galaxias auratus . Analysis of stomach contents and consumption estimates based on collections of fish every 3 h over three 24-h periods in summer 2002/2003 revealed that feeding always occurred during both day and night, with no obvious peaks. We also estimated the gastric evacuation rate of G. auratus in a laboratory experiment using the two prey species found to be dominant in stomachs of field-sampled fish. The relationship was best described by an exponential model, with rate parameters ( R ) of 0.104 and 0.081 for the evacuation of the amphipod, Austrochiltonia australis , and the cladoceran, Daphnia carinata , at water temperatures of 11.5 and 16.5 °C, respectively. Daily ration of G. auratus in summer was estimated to be approximately 3% (dry body weight) using the models of Elliot & Persson and Eggers. Galaxias auratus appears to be unusual in that its feeding pattern cannot be classified as nocturnal, diurnal or crepuscular, but its gastric evacuation and daily ration estimates are still similar to other comparable Northern Hemisphere freshwater fishes.  相似文献   

7.
Environmental variability and growth‐rate histories from hatching to capture were investigated for larval Japanese sardine (Sardinops melanostictus) and Japanese anchovy (Engraulis japonicus). Larvae collected around the front of the Kuroshio Current were examined using otolith microstructure analysis, and their movement was estimated from numerical particle‐tracking experiments. Sardine larvae collected inshore of the Kuroshio front originated from a coastal area near the sampling site, while those collected in the offshore area originated from an area 500–800 km west‐southwest of the sampling site. Anchovy larvae collected both inshore and offshore had been transported from widely distributed spawning areas located west of the sampling area. At the age of 13–14 days for sardine and 19–20 days for anchovy, the offshore group exhibited significantly higher mean growth rates than did the inshore group. Although the offshore area was generally warmer than the inshore area, temporal variations in growth rate are not attributable solely to fluctuations in environmental temperature. While previous studies have examined the relationship between larval growth rates and environment based solely on data at capture, the methods used in the present study, combining otolith analysis and numerical particle‐tracking experiments, utilize data up until hatching. Although the relationship between growth rate and environment was not fully confirmed, this approach will greatly advance our understanding of fish population dynamics.  相似文献   

8.
This study evaluated efficacy and toxicity of the pyrazinoisoquinoline anthelmintic praziquantel (PZQ) in barbel infected with metacercariae of Diplostomum spathaceum and adult Pomphorhynchus laevis, and assessed antioxidant biomarkers and the lipid peroxidation response in juvenile barbel post‐treatment. The estimated 96‐hr LC50 of PZQ was 28.6 mg/L. For evaluation of efficacy, barbel naturally infected with D. spathaceum were exposed to a 10 and 20 mg/L PZQ 4‐day bath treatment. Both concentrations were 100% effective against D. spathaceum and significantly (< .01) affected the activity of catalase, superoxide dismutase, glutathione reductase and glutathione‐S‐transferase as well as levels of reduced glutathione in liver and muscle. The efficacy of orally administered PZQ was assessed in adult barbel naturally infected with P. laevis. Fish were administered 10, 30 and 50 mg/kg of body weight and examined via gut dissection after 6 days. The 50 mg/kg dose significantly decreased the intensity of infection. Praziquantel is a feasible bath treatment for barbel infected with D. spathaceum and has potential for oral treatment of broodfish infected with P. laevis.  相似文献   

9.
A combined optical particle counter (OPC) and multiple opening and closing net and environmental sensing system (MOCNESS) was used to obtain simultaneous measurements of the fine‐scale distribution of ‘prey‐sized’ particles and the vertical distribution of larvae of Pacific hake (Merluccius productus). Physical properties were also measured. The data were used to describe the feeding ecology of Pacific hake larvae, and to explore the effects of prey abundance, time of day, temperature and depth on feeding. Pacific hake larvae consumed a wide variety of prey including copepod eggs, nauplii, copepodites, and euphausiid metanauplii. Calanoid copepodites comprised > 75% of the ingested prey volume. First‐feeding larvae were 2.5–3.0 mm SL. These larvae consumed prey 40–200 μm wide. Larvae 3.0–6.5 mm long ingested prey 40–400 μm wide and larvae > 6.5 mm long ingested prey 400–700 μm wide. There were clear diel patterns in feeding incidence and prey volume ingested. Feeding commenced between 06:01 and 08:00 hours PST and continued until ~ 16:00 hours. Ingested prey items remained in the gut until complete gut evacuation occurred near dawn. The volume of food ingested was estimated using two indices, the cube root of the prey volume (CRPV) and the cube root of the stomach volume (CRSV). Standard length, log elapsed time since gut evacuation, depth and particle biovolume contributed significantly to variation in both indices. Temperature did not contribute to variability in either CRPV or CRSV.  相似文献   

10.
《水生生物资源》1998,11(5):325-334
Patterns in fish taxa composition were examined in Portuguese reservoirs to assess whether distinct types of assemblages exist. Furthermore, the environmental variables most tightly associated with assemblage-level patterns were identified. Classification of the fish taxa-by-reservoirs matrix revealed four major groups. Groups were separated by means of canonical correspondence analysis according to (by decreasing correlation with canonical axis): air temperature, annual rainfall, surface elevation, trophic state, mean depth and reservoir placement within the basin. In addition to these variables, stocking practices and predation likely contributed to assemblage composition. Assemblages in group A were distinguished by the permanent presence of largemouth bass (Micropterus salmoides) and the absence of trout (Salmo trutta and/or Oncorhynchus mykiss), nase (Chondrostoma sp.) and barbel (Barbus sp.). Group B assemblages invariably included bass, barbel and nase, while pumpkinseed (Lepomis gibbosus) was frequent and trout was extremely rare. Assemblages in group C were also characterised by nase and barbel, but in contrast to group B, trout was frequent, whereas bass was rare and pumpkinseed was absent. Group D assemblages consisted exclusively of trout and chub (Leuciscus sp.). The relationships observed parallel patterns detected in natural lakes to a certain extent, despite the critical human influence and the probable instability of some of the patterns detected.  相似文献   

11.
Several published models exist for simulating vertical profiles of pelagic fish eggs, but no one has rigorously assessed their capacity to explain observed variability. In this study, we applied a steady‐state model, with four different formulations for vertical diffusivity, to northern anchovy (Engraulis mordax) and Pacific sardine (Sardinops sagax) eggs in the California Current region. Vertical mixing profiles, based on wind speed and hydrography, were combined with estimated terminal ascent velocities of the eggs based on measurements of egg buoyancy and size, to simulate the vertical profiles of the eggs. We evaluated model performance with two data sets: (1) vertically stratified tows for both species and (2) paired samples for sardine eggs from 3‐m depth and in vertically integrated tows. We used two criteria: whether the model predicted individual observed vertical profiles (1) as well as the observed mean and (2) better than the observed mean. Model predictions made with the formulation producing the most gradual profile of vertical diffusivity provided the best match to observations from both data sets and for both species. Addition of a random error term to the terminal ascent velocity further improved prediction for anchovy eggs, but not sardine. For the paired data, model prediction of integrated abundance from abundance at 3‐m depth had significantly lower mean square error than prediction based on a linear regression of 3 m on integrated abundance. Our results support the feasibility of using data from the Continuous Underway Fish Egg Sampler quantitatively as well as qualitatively in stock assessments.  相似文献   

12.
This study aimed to investigate the feeding behaviour (particularly gut fullness and evacuation, preying on rotifers and feeding preference in the water column) of the calanoid copepod, Pseudodiaptomus hessei, as a potential live feed species for aquaculture. Fed and starved, male and female P. hessei were fed rotifers (Brachionus plicatilis) in the presence and absence of microalgae for 24 hr. Starved copepods consumed more rotifers (11.31 ± 1.01, individual rotifers) than fed (8.06 ± 1.01, individual rotifers) while the number of rotifers consumed in the presence of microalgae was similar when fed or starved. Gut fullness and evacuation was determined by feeding copepods two different cell size microalgae species (Tetraselmis suecica and Isochrysis galbana). Gut fullness and evacuation percentage were observed under the dissecting microscope (as 0, 25, 50, 75 and 100%). Copepods fed on T. suecica (large cell) filled their guts more rapidly, while those fed on I. galbana (small cell) evacuated their guts faster. Feeding preference was determined using a multifactorial experiment where copepods were fed two microalgae species, T. suecica and I. galbana, each presented as benthic and planktonic food sources. P. hessei preferred to feed on planktonic microalgae first regardless of microalgae choice species for ±80 min, before shifting to benthic food source. This information can be used as baseline information for aquaculturists to rear the species as live feed for marine fish larvae.  相似文献   

13.
Abstract – In 1997 and 1998, sampling was conducted on the Missouri and Yellowstone rivers, North Dakota, to obtain information on the distribution, abundance, and habitat use of the flathead chub (Platygobio gracilis Richardson), sicklefin chub (Macrhybopsis meeki Jordan & Evermann), sturgeon chub (Macrhybopsis gelida Girard), and western silvery minnow (Hybognathus argyritis Girard), four declining fish species (family Cyprinidae) native to the Missouri River basin, USA. The study area consisted of four distinct river segments near the confluence of the Missouri and Yellowstone rivers – three moderately altered segments that were influenced by a main‐stem dam and one quasi‐natural segment. One moderately altered segment was located at the confluence of the two rivers (mixing‐zone segment (MZS)). The other two moderately altered segments were in the Missouri River adjacent to the MZS and extended up‐river (above‐confluence segment (ACS)) and down‐river (below‐confluence segment (BCS)) from this segment. The quasi‐natural segment (Yellowstone River segment (YRS)) extended up‐river from the MZS in the Yellowstone River. Catch rates with the trawl for sicklefin chub and sturgeon chub and catch rates with the bag seine for flathead chub and western silvery minnow were highest in the BCS and YRS. Most sicklefin and sturgeon chubs were captured in the deep, high‐velocity main channel habitat with the trawl (sicklefin chub, 97%; sturgeon chub, 85%), whereas most flathead chub and western silvery minnow were captured in the shallow, low‐velocity channel border habitat with the bag seine (flathead chub, 99%; western silvery minnow, 98%). Best‐fit regression models correctly predicted the presence or absence of sicklefin chub, flathead chub, and western silvery minnow more than 80% of the time. Sturgeon chub presence and absence were predicted correctly 55% of the time. Best‐fit regression models fit to fish number data for flathead chub, sicklefin chub, and sturgeon chub and fish catch‐per‐unit‐effort (CPUE) data for flathead chub also provided good fits, with R2 values ranging from 0.32 to 0.55 (P < 0.0001). The higher density and catch of the four native minnows in the YRS and BCS suggest that these two segments are better habitat than the ACS and MZS.  相似文献   

14.
为研究斑点叉尾(鱼回)[体质量(115.55±7.54)g]对全植物蛋白饲料的胃排空,实验比较了3种常用数学模型对其排空曲线的拟合程度,同时探究了摄食过程中消化道内容物的水分、pH和消化酶的变化规律.结果发现,3种数学模型均可较好地描述斑点叉尾(鱼回)胃排空曲线,平方根模型最适于定量描述,指数模型次之,线性模型较差.根据平方根模型分别计算得到斑点叉尾(鱼回)胃50%排空时间为12.8 h(以干重计),完全排空约36 h.在摄食后0~36 h内,内容物水分含量在后肠保持不变,在胃部呈缓慢上升趋势,而在前肠和中肠则呈先上升后下降趋势.消化道各段内容物pH在摄食后3h内均显著下降,3~30 h间总体保持平稳状态,在30 h后又呈显著上升趋势.消化道各段蛋白酶、脂肪酶和淀粉酶比活力在摄食3h内显著上升,并在3~30 h内保持相对稳定水平,摄食30 h后呈显著下降趋势.整个摄食过程中,消化道各段消化酶比活力大小依次为前肠>中肠>后肠>胃.研究表明,斑点叉尾(鱼回)在摄食过程中,消化道各段内容物的水分、pH和消化酶比活力均随时间呈现相应的规律性变化.而这些内环境参数的相互作用,综合影响了特定胃排空时间的形成.  相似文献   

15.
Rheophilic cyprinid populations are in decline in many European rivers and have become target species of conservation and river restoration. This is especially true for the European nase (Chondrostoma nasus), a lithophilic species for which the early life stages pose the first bottlenecks in successful population development. In this study, egg dispersal at the substrate surface as well as within the stream interstitial was evaluated and the development of nase eggs was tested at three spawning grounds in the German Alpine Foreland. New incubation systems for cyprinid eggs as well as reference incubation boxes were developed. A significantly higher number of nase eggs (95.5%) were deposited within the stream interstitial compared to eggs sticking to the substrate surface (4.5%). Most eggs successfully developed within the stream interstitial, and hatched larvae moved deeper into the stream substrate. Higher fine sediment accumulation rates in incubation systems had a negative impact on hatching rates. Our results suggest that a permeable, well‐oxygenated stream interstitial at spawning grounds can greatly enhance hatching rates and successful development of nase, as previously found for other taxa such as salmonids. Furthermore, movements of hatched larvae into deeper layers of the stream interstitial underline its importance not only for egg development, but also as shelter for early life stages. Future conservation and restoration efforts should thus consider more intensively stream interstitial conditions on spawning grounds, including evaluating physical characteristics, fine sediment accumulation as well as bioindication with suitable incubation systems for cyprinids.  相似文献   

16.
Temporary accumulation of ascorbic acid 2-sulfate (AAS) was measured to estimate food intake and gut evacuation in larvae of African catfish. Fish larvae were fed decapsulated cysts of Artemia containing AAS. In a first experiment it was found that no biosynthesis of AAS occurs in the larvae of this species. In a second experiment, the gut contents of the fish larvae fed were calculated as they changed during development. In a third experiment, the gut evacuation rate of fish larvae was determined during continuous and discontinuous feeding regimes in the first five days after the start of exogenous feeding. Food consumption by catfish larvae increased from 46.5% of their body dry weight (BDW) on day 1 after the start of exogenous feeding to 53.8% BDW on day 3. Thereafter, food consumption decreased to 27.8% BDW on day 5. A similar pattern was observed for gut evacuation, which increased during the first days of exogenous feeding and decreased as fish growth continued. The rate of gut evacuation in a continuous feeding regime was significantly higher (P < 0.05) than that under discontinuous feeding. On day 1 post-hatch and 7 h after first food ingestion the fish larvae evacuated 87% of the food in continuous feeding compared with 43% under discontinuous feeding. It was found that gut emptying differs during larval development. Under continuous feeding, on days 1 and 3 post-hatch and 11 h after the first meal 90% of the food was evacuated compared with 71% evacuated on day 5. The advantages and limitations of the AAS method for estimation of food consumption by fish larvae are discussed.  相似文献   

17.
Atlantic salmon populations have experienced strong declines in most large European rivers. In the Loire Basin, France, a major restocking effort has been carried out on the Allier River to reduce the wild population decline. This study aimed at investigating the trophic insertion of hatchery‐reared salmon parr and whether they compete for resources with native fish species. For this purpose, two riffles located in the upstream and downstream parts of the restocked area have been surveyed monthly following the initial 0+ salmon fry release. 0+ parr densities remained high upstream, with autumnal values greater than those recommended to maximise smolt production. In contrast, downstream densities declined to weak values despite a faster increase in size, probably mainly due to summer temperatures rising above the discomfort threshold. By analysing the vulnerability to predation of ingested invertebrate prey, we highlighted the role of habitat constraints in driving most of the different fish species to a likely opportunistic utilisation of available food resources. As a result, species such as stone loaches and barbel juveniles exhibited narrow trophic niches and high overlaps with 0+ parr. Nonetheless, both abundant prey resources and spatial or temporal habitat segregation have limited interspecific competition, enabling competitive coexistence of sympatric species, except for barbel juveniles in certain circumstances. Therefore, our findings suggest that future restocking programmes should carefully consider the thermal and hydraulic conditions regarding further smolt production as well as their general trophic context, according to the potential inconvenience of restocked salmon fry arrival relative to native species.  相似文献   

18.
Abstract– The effect of meal size on the gastric evacuation rate of burbot Lota lota (L.), was determined at a constant temperature of 1.5°C. Burbot were fed vendace Coregonus albula (L.), in varying amounts from 1.0% to 12.6% of burbot weight. Although gastric evacuation rate decreased exponentially with increasing meal size, the absolute amount of food evacuated per day (g. day−1 increased when meal size increased. The estimated maximum daily gastric evacuation rates were 0.8, 1.3 and 1.6 g/day with meal sizes 1%, 5% and 10% of burbot weight (200 g). No difference in gastric evacuation rate was observed between meals of the same size (8 g) but which consisted of either one or three vendace.  相似文献   

19.
We determined the habitat usage and habitat connectivity of juvenile Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon in continental shelf waters off Washington and Oregon, based on samples collected every June for 9 yr (1998–2006). Habitat usage and connectivity were evaluated using SeaWiFS satellite‐derived chlorophyll a data and water depth. Logistic regression models were developed for both species, and habitats were first classified using a threshold value estimated from a receiver operating characteristic curve. A Bernoulli random process using catch probabilities from observed data, i.e. the frequency of occurrence of a fish divided by the number of times a station was surveyed, was applied to reclassify stations. Zero‐catch probabilities of yearling Chinook and yearling coho salmon decreased with increases in chlorophyll a concentration, and with decreases in water depth. From 1998 to 2006, ~ 47% of stations surveyed were classified as unfavorable habitat for yearling Chinook salmon and ~ 53% for yearling coho salmon. Potentially favorable habitat varied among years and ranged from 9 856 to 15 120 km2 (Chinook) and from 14 800 to 16 736 km2 (coho). For both species, the smallest habitat area occurred in 1998, an El Niño year. Favorable habitats for yearling Chinook salmon were more isolated in 1998 and 2005 than in other years. Both species had larger and more continuous favorable habitat areas along the Washington coast than along the Oregon coast. The favorable habitats were also larger and more continuous nearshore than offshore for both species. Further investigations on large‐scale transport, mesoscale physical features, and prey and predator availability in the study area are necessary to explain the spatial arrangement of juvenile salmon habitats in continental shelf waters.  相似文献   

20.
In partial protection management areas such as Recreational Fishing Havens (RFHs) where commercial fishing is prohibited there are fewer sampling methods available for quantifying the relative abundance of species. Consequently, a framework is needed in such areas to decide whether sampling should be based on: (1) fishery‐independent techniques; (2) fishery‐dependent methods that rely on recreational fishery harvests; or (3) a combination of the two. This study compared fishery‐independent data derived from baited remote underwater video stations (BRUVS) and independent fishing surveys (IFS) with fishery‐dependent data based on recreational angler surveys (AS) to identify the fish species that were best enumerated by each method in two Australian RFHs. Each method captured/detected disparate species and each consistently showed correlations with the relative abundance of particular suites of species. The species that were correlated with and best enumerated by BRUVS were Microcanthus strigatus (Cuvier) and Pelates sexlineatus (Qouy & Gaimard); those correlated with IFS were Gerres subfasciatus Cuvier, Girella tricuspidata (Qouy & Gaimard), Mugil cephalus L. and Pomatomus saltatrix (L.); and those correlated with AS were Platycephalus fuscus Cuvier and Acanthopagrus australis (Owen). By identifying the species that were best quantified by each method, this study facilitates accurate monitoring of key species within RFHs.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号