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1.
Advanced walleye (Sander vitreus) and yellow perch (Perca flavescens) fingerlings are produced by habituating pond-reared fingerlings to commercial feed. Success of the habituation phase depends on many variables. Among these, diet contrast/visibility is an important variable for habituation success. The objective of this study was to compare the effect of turbid water (≥100 nephelometric turbidity unit, NTU) and clear water culture conditions during the habituation phase for these two species. In 2005, 12 150 L black-cuboidal tanks with in-tank lighting were stocked at a rate of 2 g/L age 0 of either walleye or yellow perch fingerlings with half of the tanks receiving turbidity (clay slurry) and cultured for 28 d. All fish were fed a commercial diet every 5 min during a 16 h daylight interval at 10%?body weight/d. Walleye in the clear treatment had higher survival (83?±?2.0%) than the turbid treatment (57?±?6.0%). The yellow perch exhibited opposite survival results: turbid treatment rates at 79?±?2.1%?and clear treatment rates at 54?±?9.2%. These results demonstrate that the addition of clay may enhance the contrast of the feed and thus improve the habituation phase for yellow perch.  相似文献   

2.
The purpose of this study was to investigate variations of glucose content, activities of enzymes involved in glycolysis and HSP70 in Litopenaeus vannamei subjected to one constant temperature (25°C) and four daily cyclical temperature change regimes (25 ± 1°C, 25 ± 2°C, 25 ± 3°C and 25 ± 4°C; max 12 am min 12 pm ). Both the glucose and HSP70 in treatment 25°C had a day/night rhythm city (L14:D10), but it gradually disappeared with the increase in temperature fluctuating amplitude. The PK activities varied more and more acutely with the increasing temperature fluctuating amplitude, especially, that in treatment 25 ± 4°C. HK activities were affected by the flux of glucose and the process of glycolysis, which tended to be stable with the increasing temperature fluctuating amplitude. Besides, the variations of PK activities were very abrupt at 25 ± 4°C, which might be unfavourable to the growth of shrimps. The temperature fluctuations affect metabolic adjustments and change the day/night rhythmicity of some physiological indicators.  相似文献   

3.
The influence of water levels on population characteristics of yellow perch, Perca flavescens (Mitchill), and walleye, Sander vitreus (Mitchill), was evaluated across a range of glacial lakes in north‐eastern South Dakota, USA. Results showed that natural variation in water levels had an important influence on frequently measured fish population characteristics. Yellow perch abundance was significantly (P < 0.10) greater during elevated water levels. Yellow perch size structure, as indexed by the proportional size distribution of quality‐ and preferred‐length fish (PSD and PSD‐P), was significantly greater during low‐water years, as was walleye PSD. Mean relative weight of walleye increased significantly during high‐water periods. The dynamic and unpredictable nature of water‐level fluctuations in glacial lakes ultimately adds complexity to management of these systems.  相似文献   

4.
This study evaluated the status of native and stocked fish species in 13 prairie lakes in central Canada over eight years (2007–14) using three metrics: resource-use (benthic versus pelagic carbon via stable isotopes); body condition (relative weight index Wr); and parasite load (cestode gut enumerations). Analyses included game and non-game fishes, like naturally occurring northern pike, Esox lucius L., and yellow perch, Perca flavescens Mitchill, but focused on stocked walleye, Sander vitreus (Mitchill) because it supports a robust recreational fishery. Walleye and northern pike were significantly more reliant on benthic carbon than yellow perch or forage fishes (p < 0.05), but this reliance was not associated with any measured environmental variables for any species. In lakes with game fishes, forage fishes exhibited higher reliance on benthic energy, possibly due to predator avoidance strategy, particularly yellow perch. Walleye body condition index was consistently lower (<95–105) than values exhibited by the other two game fishes (81–139), and parasites were only common in walleye and associated with lake-water salinity (r2 = 0.93, p < 0.05) and sex (p < 0.05). Based on the results, the most desirable game fish, walleye, appears less resilient to environmental variability than northern pike and yellow perch, making this species more susceptible to impacts of future climate change.  相似文献   

5.
Abstract Predation is an important force structuring aquatic communities, but predator–prey interactions are complex and regulated by multiple factors. Invasive fishes may interact with native fishes to alter predator–prey preferences and community dynamics. For example, common carp, Cyprinus carpio L., is an invasive species that can become abundant and negatively affect aquatic ecosystems. Juvenile common carp are occasionally found in predator diets, but predator preferences for common carp compared with alternative prey remains unknown. Prey selection and feeding behaviour of five piscivores (flathead catfish, Pylodictis olivaris (Rafinesque); largemouth bass, Micropterus salmoides (Lacepède); smallmouth bass, M. dolomieu Lacepède; walleye, Sander vitreus (Mitchill); and northern pike, Esox lucius L.) foraging on juvenile common carp and two alternative prey (fathead minnow, Pimephales promelas Rafinesque, and yellow perch, Perca flavescens Mitchill) at variable densities and habitats were evaluated. Common carp and fathead minnow were generally selected for or neutrally selected across predator species, habitat types and prey assemblages. By contrast, yellow perch was generally selected against. Common carp were easily captured but difficult to manipulate and ingest compared with other prey. These results reveal that common carp are vulnerable to a variety of predators, suggesting control of this detrimental invader may be possible through biomanipulation.  相似文献   

6.
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7.
As a preliminary investigation into the effects of environmental factors on gonadal development using adaptive physiological characteristics, we examined the involvement of photoperiod and water temperature in the ovarian development of the red‐spotted grouper, Epinephelus akaara. During October 2014 (non‐breeding season), the photoperiod and water temperature were adjusted to 12L:12D and 18°C respectively. Every 3 weeks, daylight was increased as follows a 13L:11D and 14L:10D in the photo‐thermal treatment group, and the control group was maintained under natural conditions. After 9 weeks, water temperature was increased to 23°C in the photo‐thermal treatment group. In photo‐thermal treatment group, GSI increased significantly after 9 weeks (1.36 ± 0.19) and 12 weeks (3.31 ± 0.20) compared with the control group. At 12 weeks after photo‐thermal treatment, all fishes matured into ovaries containing late vitellogenic oocytes. The expression of FSHβ and LHβ mRNAs also increased significantly. However, in the control group, the ovarian development was maintained at an immature stage. Based on these results, we demonstrate that exposure to long photoperiod and high water temperature can induce the sexual maturation of immature red‐spotted grouper during the non‐breeding season.  相似文献   

8.
The movement of adult muskellunge, Esox masquinongy Mitchill, has been investigated in a variety of systems, but temperature selection by muskellunge has not been examined where well‐oxygenated waters were available over a range of temperatures for much of the year. Thirty subadult and adult muskellunge tagged internally with temperature‐sensing radio tags were tracked from March 2010 to March 2011 in a Tennessee reservoir. Mean tag temperatures were 18.9 °C in spring (March to May), 22.1 °C in summer (June to August), 16.5 °C in autumn and 9.8 °C in winter (December to February). When the greatest range in water temperatures was available (7.1–33.3 °C; May to early August 2010), their realised thermal niche (mean ± 1 SD) was 22.3 °C ± 1.8; the realised thermal niche was affected by fish size (smaller fish selected slightly warmer temperatures) but not sex. An electric generating steam plant discharging warm water resumed operation in January 2011, and most (86%) tagged fish occupied the plume where temperatures were ≈10 °C warmer than ambient water temperatures. No mortalities were observed 15 days later when plant operations ceased. Their affinity for the heated plume prompted concerns that muskellunge will be too easily exploited when the plant operates during winter.  相似文献   

9.
The effect of incubation temperature on embryonic development and yolk‐sac larva of the Pacific red snapper Lutjanus peru were evaluated by testing the effect of 26, 28 and 30°C, as this is the natural thermal interval reported during the spawning season of Pacific red snapper in the Gulf of California, Mexico. Sixteen developmental stages were observed. The incubation temperature affected the rate of development and time to hatching, being shorter at 30 than at 26°C, but no significant effect (P < 0.05) on larval length at hatching was registered. The depletion rate of yolk sac and oil globule was affected by incubation temperature particularly during the first 12 h post hatching (hph). At the end of the experiment (48 hph), significantly (P < 0.05) larger larvae were recorded at 26°C (TL = 3.22 ± 0.01 mm) than at 28° (TL = 3.01 ± 0.02 mm) and 30°C (TL = 2.97 ± 0.05 mm). Incubation of newly fertilized eggs at 26°C produces larger larvae, which may help to improve feeding efficiency and survival during first feeding.  相似文献   

10.
This study sought to determine the optimal temperature(s) for aquaculture of juvenile red‐spotted grouper Epinephelus akaara (Temminck & Schlegel) (mean initial BW: 3.1 g). Growth performance, insulin‐like growth factor 1 (IGF‐1) expression and thermal stress responses (plasma cortisol, glucose, and hepatic heat shock protein 60 expression) were evaluated at three constant temperatures (24°C, 26°C and 28°C) in a 2‐week trial. At the end of the trial, final BW was significantly higher at 26°C and 28°C than at 24°C (p < 0.05); a quadratic regression analysis of final BW showed the optimum temperature for growth was 27.5°C (p < 0.05, R2 = 0.806). The highest hepatic IGF‐1 expression was observed at 26°C (p < 0.05). On the other hand, hepatic heat shock protein 60 expression was highest at 28°C (p < 0.05), suggesting thermal stress. In conclusion, temperature optima, which support excellent growth but induce minimal thermal stress, was 26°C. This fine information within a narrow temperature range is expected to give empirical information for red‐spotted grouper farmers to sustain maximal production efficiency with avoiding thermal stress and to determine the future location of production, especially in consideration of arising seawater temperatures.  相似文献   

11.
A cell line, WE-cfin11f, with a fibroblast-like morphology was developed from a walleye caudal fin and used to study the intersection of thermobiology of walleye, Sander vitreus (Mitchill), with the thermal requirements for replication of viral haemorrhagic septicaemia virus (VHSV) IVb. WE-cfin11f proliferated from 10 to 32 °C and endured as a monolayer for at least a week at 1–34 °C. WE-cfin11f adopted an epithelial shape and did not proliferate at 4 °C. Adding VHSV IVb to cultures at 4 and 14 °C but not 26 °C led to cytopathic effects (CPE) and virus production. At 4 °C, virus production developed more slowly, but Western blotting showed more N protein accumulation. Infecting monolayer cultures at 4 °C for 7 days and then shifting them to 26 °C resulted in the monolayers being broken in small areas by CPE, but with time at 26 °C, the monolayers were restored. These results suggest that at 26 °C, the VHSV IVb life cycle stages responsible for CPE can be completed, but the production of virus and the initiation of infections cannot be accomplished.  相似文献   

12.
The ontogeny of the cortisol stress response in yellow perch (Perca flavescens) was documented by measuring resting and stress-induced whole-body cortisol levels in fish at several early development stages. In newly fertilized eggs resting cortisol levels averaged 41.0 ± 3.0 pg/embryo, and decreased to 8.0 ± 3.0 pg/embryo by day 6 where they remained constant until hatch on day 10. Acute stress challenge tests (30 sec cold shock) conducted on embryonic (days 6 and 8 post-fertilization) and larval (hatch and 2 days post-hatch) yellow perch revealed no differences in whole-body cortisol levels between stressed and unstressed individuals. In acute stress challenge tests (30 sec net confinement) conducted on post-hatch yellow perch, differences in cortisol levels between stressed (30 min post-stress) and unstressed fish were detected one week after hatching (12.3 ± 1.6 ng/g and 7.0 ± 1.3 ng/g, respectively). The magnitude of the stress response was greater in 2- to 5-week-old fish than in one-week-old fish. Changes in post-stress cortisol levels were closely associated with changes in interrenal morphology. Cumulatively, these results indicate that cortisol biosynthesis, integration and maturation of the hypothalamic-pituitary-interrenal (HPI) axis can be observed in yellow perch as early as one week after hatching. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

13.
Calanoid copepods, including species of the genus Acartia, are commonly used as larval diets for marine finfish. This study aimed to determine the separate effects of water temperature (18, 22, 24, 28° ± 0.5°C) and photoperiod (24L:0D; 18L:6D; 12L:12D; 8L:18D; 0L:24D) on Acartia grani egg production (EP), hatching rate (EHR) and population growth. Egg production rate was not affected by the two abiotic parameters. A. grani eggs incubated at T24°C and T28°C were the first to achieve 50% hatching rate (23–25 hr), with significant differences at the end of the experiment (48 hr) between T28°C treatment (EHR 88 ± 5%) and T18°C treatment (EHR 65 ± 2%). However, different temperature regimes did not affect final number of individuals in population growth experiment. Still, when eggs were excluded from data, population at lower temperatures (18°C) was mainly composed by the nauplii stage (72%), while at higher temperatures (24°C and 28°C) more than 60% of the population was composed by copepodites and adults. A. grani subjected to long‐day photoperiods had significantly lower EHR (16.7% at 24L:0D; 20.8% at 18L:6D) than at short‐day photoperiods (52.6% at 6L:18D; 50.0% at 0L:24D). In population growth experiment, eggs were the most common life stage after 12‐day culture. Lowest population number was found at constant light conditions (665.0 ± 197.1), suggesting higher metabolic rates and depletion of energy reserves in long‐day conditions. This study expanded knowledge on the biological response of A. grani to separate temperature and photoperiod regimes, and provided ground to improve the culture of this potential life feed species for hatcheries.  相似文献   

14.
Megalocytiviruses cause high mortality diseases that have seriously impacted aquaculture, with the most frequent outbreaks occurring in East and South‐East Asia. The international trade of juvenile fish for food and ornamental aquaculture has aided the spread of these viruses, which have spread to Europe and Australia and other regions. Australian freshwater fishes were examined for susceptibility to infection with the exotic megalocytivirus, dwarf gourami iridovirus (DGIV), which belongs to a group with the type species, Infectious spleen and kidney necrosis virus (ISKNV). Fish were held at 23 ± 1 °C and challenged by intraperitoneal (IP) injection or by cohabitation with Murray cod, Maccullochella peelii (Mitchell) infected with DGIV. A species was deemed to be susceptible to DGIV based on evidence of viral replication, as determined by qPCR, and megalocytic inclusion bodies observed histologically. Horizontal transmission occurred between infected Murray cod and golden perch, Macquaria ambigua (Richardson), Macquarie perch, Macquaria australasica (Cuvier) and Murray cod. This indicated that DGIV shed from infected fish held at 23 °C can survive in fresh water and subsequently infect these naïve fish. Further, DGIV administered IP was highly pathogenic to golden perch, Macquarie perch and Murray cod. Compared to these species, the susceptibility of southern pygmy perch, Nannoperca australis (Gunther) was lower. Freshwater catfish (dewfish), Tandanus tandanus (Mitchell), were not susceptible under the experimental conditions based on the absence of clinical disease, mortality and virus replication. This study showed the potential risks associated with naïve and DGIV‐infected fish sharing a common water source.  相似文献   

15.
Determining the factors that influence recruitment to sequential ontogenetic stages is critical for understanding recruitment dynamics of fish and for effective management of sportfish, particularly in dynamic and unpredictable environments. We sampled walleye (Sander vitreus) and white bass (Morone chrysops) at 3 ontogenetic stages (age 0 during spring: ‘age‐0 larval’; age 0 during autumn: ‘age‐0 juvenile’; and age 1 during autumn: ‘age‐1 juvenile’) from 3 reservoirs. We developed multiple linear regression models to describe factors influencing age‐0 larval, age‐0 juvenile and age‐1 juvenile walleye and white bass abundance indices. Our models explained 40–80% (68 ± 9%; mean ± SE) and 71%–97% (81 ± 6%) of the variability in catch for walleye and white bass respectively. For walleye, gizzard shad were present in the candidate model sets for all three ontogenetic stages we assessed. For white bass, there was no unifying variable in all three stage‐specific candidate model sets, although walleye abundance was present in two of the three white bass candidate model sets. We were able to determine several factors affecting walleye and white bass year‐class strength at multiple ontogenetic stages; comprehensive analyses of factors influencing recruitment to multiple early ontogenetic stages are seemingly rare in the literature. Our models demonstrate the interdependency among early ontogenetic stages and the complexities involved with sportfish recruitment.  相似文献   

16.
We carried out an experiment to determine how rapidly the early incubation temperature of Atlantic cod eggs can be increased without affecting normal embryonic development and hatching. Atlantic cod eggs were incubated at a constant low temperature (4.5 ± 0.5°C; T5 – control) and four temperature increment treatments where the temperatures were increased stepwise from 4.5°C at zygote stage to 9.5 ± 05°C (T1‐8 h, T2‐32 h, T3‐64 h and T4‐96 h). Embryonic cell symmetry, embryonic mortality, hatching success and larval skeletal abnormalities, length and yolk sac volume were recorded. Larval samples were also taken at hatch for histological analysis. Except for higher egg mortality and lower hatching success in the T1, the differences among experimental groups were minor. Cell asymmetries and embryo mortalities were not significantly different between the control and T2–T4 treatment groups. Control larvae were significantly longer and had smaller yolk reserves at hatch than T1–T4 larvae and larvae from T2 had the largest yolk reserves. Tissue and organ histology of hatched larvae were similar. Considering embryonic cleavage pattern, hatching success and larval morphology and histology, a gradual increment of temperature in 32 h seems to be the better choice for future developmental programming studies in Atlantic cod.  相似文献   

17.
Abstract

Temperature-dependent growth models were developed for juvenile yellow perch, Perca flavescens (Mitchell), in eastern South Dakota. Age-0 yellow perch were held in a circular culture tank for two months and trained to accept a pelleted diet. Five temperature treatments (16, 19, 22, 25, and 28°C) were randomly assigned in triplicate to 15, 38-L tanks containing 10 fish averaging 84±0.4 mm total length and 7.4±0.1g. Instantaneous growth rates (biweekly) for weight were highest for the 25°C treatment and lowest for the 16°C treatment. Mean length increases for the 84-day trial were 16.6, 33.3,41.1,45.1, and 40.5 mm at 16, 19,22,25, and 28°C, respectively. Mean weight increases at those respective temperatures were 4.0,11.6 15.3,17.3, and 16.6 g. Cubic polynomial equations were empirically derived to predict maximum growth rates for total length (AL, mm/day) and weight (AW, g/day) from temperature (T):

ΔL = -1.2299 + 0.1015·T + 5.566e?04·T2-7.206e?05·T3(r2 =0.99);and ΔW = -0.6052 + 0.0508 · T - 2.287e?04 · T2 - 2.028e?05 · T3 (r2 = 0.99).

Estimates derived from these analyses indicated that maximum growth under these conditions ranged from 23.4 to 25.4°C for length and 24.8 to 26.0°C for weight. The overlap temperature range (24.8 to 25.4°C) from these model predictions should be a desirable target range for maximizing growth performance in length and weight of South Dakota yellow perch fingerlings.  相似文献   

18.
The trade of live Cancer pagurus in Portugal is totally dependent on imports, mainly from UK. Animals are transported for 48–58 h in conditions that promote high mortalities (40–60%) due to cumulative stressors. The present work aimed to optimize transport, by comparing the physiological responses of edible crab during different simulated live shipment systems for 48 h and recovery conditions: (a) immersed crabs at 12°C; and (b) air‐exposed crabs at 4°C and subsequent recovery at 16°C with and without pre‐acclimation. Both simulated transport systems induced physiological stress, culminating in 25% mortality in immersed conditions and only 4% in air‐exposed conditions. Both systems elicited anaerobic responses marked by hyperglycaemia and increased l ‐lactate concentration in haemolymph. At the end of the recovery period only air‐exposed animals resumed to l ‐lactate and pH control values, the lowest mortality was achieved with crabs acclimated at the lowest temperature (from 6 to 16°C at 1.5°C/h). Overall, results showed that crabs can be transported in air‐exposed conditions at 4°C and acclimated from 6 to 16°C and reach similar physiological conditions than the traditional transport in immersed conditions at 12°C.  相似文献   

19.
Abstract – Piscivorous fish can affect prey growth in two ways: directly by reducing prey density and indirectly by inducing predator-avoidance behaviors. We investigated these two pathways in yellow perch ( Perca flavescens ) growth responses to walleye ( Stizostedion vitreum ) stocking in Canadarago Lake, New York (USA) using a 25-year time series. Before walleye stocking, yellow perch growth rate was low and independent of body size. As walleye abundance increased, yellow perch growth increased and became size-dependent. The switch to size-dependent growth occurred in 1 year, indicating a rapid behavioral response to predators. Mean growth rate increased more gradually and was linearly related to walleye density, indicating a slower numerical effect of walleye on yellow perch densities. Although the net effect was an increase in perch growth, small perch growth initially decreased as walleye became established. Therefore, the combination of numerical and behavioral effects produced a complex pattern of size-dependent changes in growth of yellow perch.  相似文献   

20.
One of the major problems involved in the controlled cultivation of Patagonian red octopus (Enteroctopus megalocyathus) is its long embryonic period ranging between 150–176 days, after which the hatching of planktonic paralarvae is achieved. The effect of temperature on the incubation of E. megalocyathus eggs was studied with the aim of establishing if a temperature higher than 12°C is effective to accelerate the embryonic development without altering their morphological and physiological conditions. Fertilized eggs obtained under controlled conditions at 11°C ± 0.1 were randomly distributed in 12 water baths of 30 L at 4 temperatures: 12, 14, 15 and 16°C ± 0.1°C. The experiment lasted until egg hatching occurred.The embryo growth rate was accelerated at 15–16°C, so the time spent in embryonic development can be reduced in 15% when compared with embryo development obtained from eggs incubated at 12°C. The embryos showed no significant differences in the final survival and were morphometrically similar in all stages of development at all temperatures. The increase in temperature from 12 to 16°C, even if it allowed a better growth, had high metabolic costs for embryos of E. megalocyathus. The activities of lipases and proteases were affected by interaction between temperature and the embryo stage, with high lipase activity observed in embryos of stage XV incubated at high temperatures and the highest levels of trypsin and chymotrypsin in stage XX at 14°C. The results suggest that 15°C could be the limit temperature to increase growth.  相似文献   

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