Effects of intra‐ and interspecific competition and hydropeaking on growth of juvenile Atlantic salmon (Salmo salar)          下载免费PDF全文

Michael Puffer  Ole K. Berg  Ari Huusko  Teppo Vehanen  Sigurd Einum 《Ecology of Freshwater Fish》2017,26(1):99-107

The effects of hydropeaking and intra‐ and interspecific competition on the growth performance (growth in length, mass and lipid content) of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta were studied in six experimental channels (three experiencing hydropeaking and three controls with a stable discharge of water). Changes in the water‐covered area in the hydropeaking channels were small to avoid fish stranding. Each channel was divided into three similar‐sized sections and stocked with either low or high density of Atlantic salmon, or a mix of Atlantic salmon and brown trout, with the density of the latter equalling the high‐density treatment of Atlantic salmon. A marked effect of competition was visible as salmon in the low‐density treatment were significantly larger (27–33%) and had a higher mass (30–38%) than salmon in both the high‐density salmon treatment and the high‐density salmon and trout treatment. Hydropeaking had only minor and insignificant effects on the growth performance: overall final length, mass and body lipid content in the salmon experiencing hydropeaking differed by ?9%, ?7% and +2% compared with controls. Furthermore, there was no indication that the competitive regime influenced hydropeaking effects. The increase in both intra‐ and interspecific competition among the juvenile salmon had a pronounced and significant effect on growth. Our study adds to the growing evidence that energetic consequences of hydropeaking are likely to be small for Atlantic salmon and that stress and mortality associated with stranding represent the main source of population impact.  相似文献   

Effects of Tank Wall Color and Up-welling Water Flow on Growth and Survival of Eurasian Perch Larvae (Perca fluviatilis)     

Sissel  Jentoft Sigurd  Øxnevad Are H.  Aastveit Øivind  Andersen 《Journal of the World Aquaculture Society》2006,37(3):313-317

The influence of tank wall color and up‐welling water flow on growth and survival of Eurasian perch larvae (Perca fluviatilis) was tested in an intensive culture system. Newly hatched larvae were fed Artemia nauplii, later combined with dry feed, and reared for 5 wk in either black tanks with up‐welling water flow or in gray tanks with or without up‐welling water flow. The perch larvae grew significantly faster in black tanks than in gray tanks regardless of water flow. Two weeks after hatching, a significantly higher mean weight was shown in larvae reared in black tanks compared to larvae reared in gray tanks with up‐welling water flow, and after 4 wk, the mean weight was significantly higher than in both of the other treatments. The difference in growth was further enhanced during the last week of the experiment, and the final mean weights were 51.1 ± 1.9 mg in black tanks with up‐welling water flow, 23.8 ± 2.1 mg in gray tanks with up‐welling water flow, and 23.7 ± 2.2 mg in gray tanks without up‐welling water flow. The cumulative mortality at the end of the experiment averaged 75% in all treatment groups. Taken together, the enhanced growth of Eurasian perch larvae in black tanks could be explained by high prey contrast and increased prey consumption. Up‐welling water flow had no impact on growth and survival of the perch larvae in gray tanks, indicating that the availability and consumption of the prey were independent of water movement.  相似文献   

Growth, feed conversion efficiency and growth heterogeneity in Atlantic halibut (Hippoglossus hippoglossus) reared at three different photoperiods     

Albert K Imsland  Atle Foss  Sigurd O Stefansson  Ian Mayer  Birgitta Norberg  Bjørn Roth  & Mads D Jenssen 《Aquaculture Research》2006,37(11):1099-1106

Juvenile Atlantic halibut, Hippoglossus hippoglossus (initial weight (SD) 191.3 (±44.7)) g, were reared for 99 days at a constant temperature of 11°C and subjected to three different light regimes from 13 September to 21 December: continuous light (LD24:0), simulated natural photoperiod of Bergen (60°25′N, LDN) and constant 20 h light:4 h dark (LD20:4). The fish reared on the different photoperiod regimes differed in their growth patterns as juveniles exposed to long days, i.e. LD20:4 and LD24:0, exhibited faster growth than those experiencing a natural photoperiod. The LD20:4 group showed the highest average specific growth rate (0.72% body weight day^?1), whereas fish on LDN displayed the lowest average specific growth rate (0.60% body weight day^?1). The final mean weights of the LD20:4 and the LD24:0 groups were 15% and 12% higher than those of the LDN group. Dividing the duration of the experiment into three time periods shows that the LD20:4 and LD24:0 had a higher feed conversion efficiency (FCE) as compared with the LDN group during the first and the last period, while a reversed situation was observed in the second period. Our data indicate a larger variation in growth rates among individuals in the best‐performing groups (here LD20:4 and LD24:0). This may indicate that formation of size hierarchies is more pronounced in groups with more homogenous growth (here LDN). Overall, our findings indicate that extended light regimes result in faster growth and better feed conversion in juvenile Atlantic halibut. In line with findings on other flatfish species, this supports the concept that constant long day:short night or continuous light regimes should be used by the farmer in order to maximize growth and improve feed conversion in Atlantic halibut.  相似文献   

Growth and parr-smolt transformation of Atlantic salmon (Salmo salar L.) under different light intensities and subsequent survival and growth in seawater     

Sigurd O. Stefansson  Tom J. Hansen  G. Lasse Taranger 《Aquacultural Engineering》1993,12(4):231-243

Groups of potential Atlantic salmon (Salmo salar L.) smolts were reared under a simulated natural photoperiod from November 1987 to May 1988. Three different light intensities were used: 27, 335 or 715 lux. Growth rate was not significantly influenced by differences in light intensity. All groups developed the silvery external appearance, increased hypo-osmoregulatory ability and decreased condition coefficient associated with smolting. Smolts from all groups were successfully acclimatized to seawater in early May. The subsequent seven months of rearing in seawater did not reveal any differences in post-smolt performance of the groups. The incidence of early maturation during the first autumn was similar in all groups. We conclude that within the limits of the light sources used in the present experiment, light intensity had no significant effect on the growth and smolting in juvenile Atlantic salmon.  相似文献   

Gastrointestinal parasites in an isolated Norwegian population of wild red deer (Cervus elaphus)     

Rebecca K Davidson  Susan J Kutz  Knut Madslien  Eric Hoberg  Kjell Handeland 《Acta veterinaria Scandinavica》2014,56(1)

Background

Thirteen red deer (Cervus elaphus), culled from the isolated population at the Mongstad Oil Refinery, Norway, were investigated for gastrointestinal helminths. These animals, enclosed by the refinery fence, do not have contact with other ruminants and have a high population density considering the available browsing area (1 km²) within the refinery site (3 km²). The population was estimated to be 110-130 at the time of culling.

Results

The helminth fauna among these sampled red deer was enumerated and species were identified based on morphology. Ostertagia leptospicularis/O. kolchida was detected in 83% [CI 55 - 95%], Spiculopteragia spiculoptera/S. mathevossiani in 92% [CI 65 - 99%] and Trichostrongylus axei in 42%, [CI 19 - 68%] of the abomasa examined. Characterisation of the intestinal parasite fauna revealed Capillaria bovis, Cooperia oncophora, Oesophagostomum venulosum, Trichuris globulosa and tapeworm fragments (presumed anoplocephalids) in seven individuals. Only one calf had an infection with more than one intestinal helminth (tapeworm fragment and Trichuris globulosa). The remaining six deer had single species intestinal infections.No significant age related trends were seen, with the exception of higher intensity of infection of T. axei in yearlings relative to other age classes. Assessment of abomasal parasite burden and body condition revealed no significant trends. In calves, statistically non-significant correlation was seen between increased parasite burden and decreased slaughter weight, whilst the opposite was seen in adults with the heaviest adults exhibiting the higher burdens. Given the small sample size the trends that were seen need further investigation. The parasite burden was aggregated with three adult red deer harbouring 75% of the total abomasal parasite count.

Conclusion

This isolated population was parasitised by a reduced subset of gastrointestinal nematodes typical of this cervid across an extensive geographic range in Eurasia. The intensity and abundance of abomasal nematodes was higher in this isolated population than reported in similar studies of red deer populations across Europe.  相似文献   

Seasonal variation in flesh quality, comparison between large and small Atlantic salmon (Salmo salar) transferred into seawater as 0+ or 1+ smolts     

Bjorn Roth  Sten Johan Sverre Johansen  Jorma Suontama  Anders Kiessling  Odd Leknes  Bjorn Guldberg  Sigurd Handeland 《Aquaculture (Amsterdam, Netherlands)》2005,250(3-4):830-840

The aim of this study was to identify the effect of growth, size and season on the flesh quality of Atlantic salmon (Salmo salar). Following smoltification, two groups of size sorted 0+ and 1+ smolts (four treatment groups in all) were measured for body weight and length in January, June and October 2002. The fish were stored on ice for 4 days before filleted and samples taken for flesh colour, fat/dry content, end pH, gaping score and texture shear force. Large fish upon smoltification grew faster during the first year at sea, while smaller fish grew faster during the second year at sea, resulting in similar weight at slaughter. Season showed the main influence on quality, where fish slaughtered in October had harder texture, higher fat content and redder colour compared to previous samples (P < 0.05). There were only minor differences between the fish slaughtered in January and June (P > 0.15). No significant differences (P > 0.05) were detected as an effect of size or smoltification age when effects of season were accounted for in the statistical model. We conclude that the observed variation in quality was an effect of changes in growth with season. We recommend that actions aimed to halter growth prior to slaughter could be an effective control measure to reduce seasonal quality variations.  相似文献   

Intraspecific Differences in Physiological Efficiency of Juvenile Atlantic Halibut Hippoglossus hippoglossus L.     

Albert K.  Imsland Thor M.  Jonassen Sigurd O.  Stefansson Shusaku  Kadowaki Marl H. G.  Berntssen 《Journal of the World Aquaculture Society》2000,31(3):285-296

We compared growth efficiency, feeding consumption, metabolism, excretion, and energy allocation in populations of juvenile Atlantic halibut from Norway, Iceland, and Canada reared at low (8 C), medium (12 C, 15 C) and high (18 C) experimental temperatures. Our findings show that protein utilization and energy allocation in juvenile Atlantic halibut varies among different populations, as the Norwegian population displayed the highest protein efficiency ratio, protein production value, and energy conversion efficiency compared to the Canadian population, while the Icelandic population showed overall intermediate growth performance. The results do not conform to a simple thermal adaptation model but might represent an example of: 1) local adaptation of fish populations; or 2) countergradient variation where shorter growing season at higher latitudes is compensated with higher physiological efficiency. These findings have implications for halibut culture, particularly in selection work focusing on growth performance.  相似文献   

Comparisons of RNA/DNA Ratios, Growth, and Metabolism in Different Populations of Juvenile Turbot Scophthalmus maximus Reared at Four Temperatures     

Albert K.  Imsland  Atle  Foss  Bjørn  Sveinsbø  Thor M.  Jonassen  Sigurd O.  Stefansson 《Journal of the World Aquaculture Society》2001,32(1):1-10

We compared RNA/DNA ratios, growth and routine oxygen consumption in populations of juvenile turbot from Norway, Scotland, and France reared at low (10 C), medium (14 C, 18 C) and high (22 C) temperatures. The relationships between growth and RNA/DNA ratios differed between temperatures, although they were always positive. Growth and RNA/DNA of the Norwegian fish were higher than those of the other populations especially at the two highest temperatures (18 C and 22 Q. Minor differences were found between the Scottish and French populations. Fish from the Norwegian population displayed the lowest oxygen consumption at these temperatures (146 and 270, 182 and 310, 192 and 328 mg O₂/kg per d, for 18 and 22 C, and Norwegian, French, and Scottish populations, respectively). Growth differences did not conform to a simple thermal adaptation model, but might represent an example of countergradient variation in growth. The findings have implications for turbot culture, particularly in selection focusing on growth performance.  相似文献   

Experimental cerebrospinal elaphostrongylosis (Elaphostrongylus rangiferi) in goats: II. Pathological findings.     

K Handeland  A Skorping 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1992,39(10):713-722

Pathological findings in 17 goat kids inoculated with 100-1,000 infective larvae of Elaphostrongylus rangiferi and autopsied 21-154 days post inoculation (p.i.) are reported. The lungs, heart, diaphragm, liver and kidneys contained small foci of necrosis or fibroblastic scarring and interstitial infiltrates of inflammatory cells. The lungs also contained many parasitic granulomas. Infarcts were observed in the myocardium and kidneys. Accumulations of inflammatory cells and granulomas were seen in the peri- and epineurium of the spinal nerve roots, connective tissue of the spinal ganglia, dura and epidural tissue of the cord, choroid plexus of the brain and leptomeninges of the entire central nervous system (CNS). Within nerve fascicles there were endoneural cell infiltrates, axon and myelin sheath degenerations and granulomas. The CNS parenchyma contained foci of traumatic encephalomyelomalacia, microgliosis, secondary axon degeneration, perivascular cuffs and granulomas. Sections of intact nematodes were found in the subarachnoid spaces, brain ventricles, central canal of the spinal cord and CNS parenchyma. Pathological findings from individual animals are compared to the clinical signs described in a separate paper. The development, migration and pathogenesis of E. rangiferi in goats are discussed.  相似文献   

Cerebrospinal elaphostrongylosis in dairy goats in northern Norway.   总被引：2，自引：0，他引：2  

K Handeland  O Sparboe 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1991,38(10):755-763

Ten carcasses and three vertebral columns from north Norwegian dairy goats, which had been killed due to clinical signs of severe neurologic disease, were received for necropsy. Pathological examination revealed nematodes and nematode ova in the central nervous system (CNS) of nine goats. Worms found by gross examination were identified as Elaphostrongylus rangiferi Mitskevich, 1960. Focal traumatic encephalomyelomalacia, apparently caused by migrating worms, perivascular cuffing, eosinophilic leptomeningitis and perineural infiltrations and granulomas, could be demonstrated in CNS sections from all 13 animals examined. Clinical signs reported were initial pruritus followed by motor weakness, lameness, paresis, reduced vision, circling, abnormal head position, bulging eyes and scoliosis. The disease occurred from September to January in regions with a considerable migrant reindeer population. It was concluded that the reported outbreaks of neurologic disease represented seasonal occurrence of cerebrospinal elaphostrongylosis caused by Elaphostrongylus rangiferi, the elaphostrongyloid nematode of reindeer (Rangifer tarandus tarandus).  相似文献