Holding wild caught red king crab,Paralithodes camtschaticus: effects of stocking density and feeding on survival and meat content          下载免费PDF全文

Sten Ivar Siikavuopio  Philip James  Bjørn Ronald Olsen  Tor Evensen  Atle Mortensen 《Aquaculture Research》2016,47(3):870-874

In this study, the effects of different stocking densities on survival, injury and meat content of captive male red king crab (mean weight = 2.6 kg) were examined. The first experiment was carried out in square plastic tanks with stocking densities of 100, 150 and 200 kg m^?3 for 56 days. In a second experiment, king crabs were kept at a stocking density of 60 kg m^?3 and were either fed or not fed. Both mortality and occurrence of injuries increased significantly with increasing stocking density. In the highest density groups, mortality and frequency of injury was 17% and 14% respectively, compared with 5% and 4% in the 150 kg m^?3 group. The percentage meat content was significantly lower at the final census compared with the initial census in all stocking density groups. In Experiment 2, there were no mortalities or injuries in either the fed or unfed treatments. The average percentage meat content increased in the fed treatment and decreased in the starved treatments. The results show that adult male king crab can maintain high survival rates at stocking densities up to 150 kg m^?3 in holding facilities of the design used in the present study for periods up to 2 months. However, to reduce mortality and frequency of injury over this period densities as low as 60 kg m^?3 and a holding system with a large bottom surface area are recommended.  相似文献   

Influence of Dietary Lipid and Protein Sources on the Sensory Quality of Organic Rainbow Trout (Oncorhynchus mykiss) After Ice Storage     

Ditte Green-Petersen  Charlotte Jacobsen  Caroline P. Baron  Ivar Lund  Henrik Hauch Nielsen 《Journal Of Aquatic Food Product Technology》2013,22(4):333-346

The influence of dietary protein and lipid sources on the quality of organic rainbow trout (Oncorhynchus mykiss) was studied. The protein and oil sources were fishmeal, fish oil, and organic vegetable protein and oils. Sensory profiling was performed during 3 to 14 days of ice storage along with lipid analyses of the fillet. Overall, the results showed that the sensory characteristics of the trout were affected in different ways during ice storage. The source of lipid seemed to affect the sensory quality at the beginning of the storage period, while the protein source seemed to have a more pronounced impact at the end of the storage period.  相似文献   

Growth performance of European whitefish [Coregonus lavaretus (L.)] under a constant light and temperature regime     

Sten I. Siikavuopio  Rune Knudsen  Per‐Arne Amundsen  Bjørn Steinar Sæther 《Aquaculture Research》2012,43(11):1592-1598

Growth, feed intake and maturation were monitored in a fast‐growing benthivore morph of European whitefish [Coregonus lavaretus (L.)] held under constant light (LD 24:0) and temperature conditions (10°C) for 415 days. Their growth was best described by polynomial regression model and no indication of seasonal patterns (e.g. winter depression) in growth rates was found. There was no significant difference in food conversion ratio (FCR) between periods during the experiment and the FCR was favourable (0.84). Furthermore, there were no differences in growth between males and females. None of the fish became sexually mature by the time the experiment was terminated, although they had reached a mean size of about 444 g. The European whitefish seems to be a promising aquaculture species as the growth rate was relatively high with a remarkable homogenous growth performance between individual fish within each experimental unit, a relatively favourable FCR, a low degree of agonistic behaviour and negligible growth depression due to internal biological rhythms or gonad maturation. These results were obtained at relatively low temperatures that should be beneficial for sustainable cost‐effective farming conditions in cold climate condition in northern Scandinavia.  相似文献   

The use of at‐sea‐sampling data to dissociate environmental variability in Norway lobster (Nephrops norvegicus) catches to improve resource exploitation efficiency within the Skagerrak/Kattegat trawl fishery          下载免费PDF全文

Jordan Feekings  Asbjørn Christensen  Patrik Jonsson  Rikke Frandsen  Mats Ulmestrand  Sten Munch‐Petersen  Bo Andersen 《Fisheries Oceanography》2015,24(4):383-392

Research into the influence of environmental variables on the behaviour of Norway lobster (Nephrops norvegicus), and hence catch rates, dates back to the 1960s (e.g., Höglund and Dybern, Diurnal and seasonal variations in the catch‐composition of Nephrops norvegicus (L.) at the Swedish west coast. ICES CM 1965/I46; Simpson, Variations in the catches of Nephrops norvegicus at different times of day and night. Rapport et Proés‐verbaux des Réunions Conseil permanent international pour 1'Exploration de la Mer 156:186). However, the use of fishery‐dependent data in identifying influential factors is relatively limited and only includes a number of papers on a limited dataset (e.g., Redant and De Clark, Diurnal variations in CPUE and length composition of the catches in a Nephrops directed fishery in the Central North Sea. ICES CM 1984/K:3; Maynou and Sardà, Influence of environmental factors on commercial trawl catches of Nephrops norvegicus (L.). ICES J. Mar. Sci. 58:1318). Here, we aimed to dissociate environmental variability in Norway lobster catches to improve resource exploitation efficiency within the Skagerrak and Kattegat trawl fisheries by utilising data collected as part of an extensive at‐sea‐sampling programme spanning 16 years. Catch rates were modelled using Generalized Additive Mixed Models (GAMMs) and considered a range of response variables, including depth, temperature, current speed, season, moon phase and time of day. The results obtained herein showed that time of day, season, depth, temperature, year, trawl type and location all significantly affect catch rates of Nephrops.  相似文献   

Yersinia enterocolitica in sheep - a high frequency of biotype 1A     

Karin S?derqvist  Sofia Boqvist  Georges Wauters  Ivar V?gsholm  Susanne Thisted-Lambertz 《Acta veterinaria Scandinavica》2012,54(1):39

Background

Pigs are regarded as the main reservoir for human pathogenic Yersinia enterocolitica, which is dominated by bioserotype 4/O:3. Other animals, including sheep, have occasionally been reported as carriers of pathogenic strains of Y. enterocolitica. To our knowledge, this is the first study performed in the Nordic countries in which the presence of Y. enterocolitica in sheep is investigated.

Methods

Tonsils and faecal samples collected from sheep slaughtered on the island Gotland (Sweden) from September 2010 through January 2011 were analysed for presence of Y. enterocolitica. In an attempt to maximize recovery, several cultural strategies were applied. Various non-selective media were used and different temperatures and durations of the enrichment were applied before subculturing on Cefsulodin Irgasan Novobiocin (CIN) agar. Presumptive Y. enterocolitica colonies were subjected to urease, API 20E and agglutination test. Yersinia enterocolitica isolates were biotyped, serotyped, and tested for pathogenicity using a TaqMan PCR directed towards the ail-gene that is associated with human pathogenic strains of Y. enterocolitica.

Results

The samples collected from 99 sheep yielded 567 presumptive Y. enterocolitica colonies. Eighty urease positive isolates, from 35 sheep, were identified as Y. enterocolitica by API 20E. Thirty-four of 35 further subtyped Y. enterocolitica isolates, all from faecal samples, belonged to biotype 1A serotype O:5, O:6. O:13,7 and O:10. One strain was Yersinia mollaretii serotype O:62. No human pathogenic strains of Y. enterocolitica were found in the investigated sheep. Other species identified were Y. kristensenii (n = 4), Y. frederiksenii/intermedia (n = 3), Providencia rettgeri (n = 2), Serratia marcescens (n = 1) and Raoultella ornithinolytica (n = 1).

Conclusions

This study does not support the hypothesis that sheep play an important role in transmission of the known human pathogenic Y. enterocolitica in the studied geographical region. However, because there are studies indicating that some strains of Y. enterocolitica biotype 1A may cause disease in humans, the relative importance of sheep as carriers of human pathogenic strains of Y. enterocolitica remains unclear. Tonsils do not appear to be favourable sites for Y. enterocolitica biotype 1A in sheep.  相似文献   

Invasive Acacia longifolia induce changes in the microbial catabolic diversity of sand dunes     

Elizabete Marchante  Annelise Kjøller  Sten Struwe  Helena Freitas 《Soil biology & biochemistry》2008,40(10):2563-2568

Acacia longifolia is one of the main plant species invading Portuguese dune ecosystems. Areas invaded by this exotic tree have reduced plant diversity and altered soil microbial processes and nutrient pools, but the impacts on microbial functional diversity in the soil have been little explored. Soil samples were collected in areas invaded by A. longifolia for more than 20 years, in areas invaded after 1995 and in non-invaded areas. Respiration responses to 20 different substrates were analysed, in order to assess the catabolic response profile (CRP) as a measure of microbial functional diversity. Five substrate groups were tested: amino acids, carbohydrates, carboxylic acids, plant litters, and plant polymers. CRP clearly discriminated between the three different areas. Respiratory responses to the individual substrates α-ketoglutaric acid, oxalic acid, starch, citric acid, and xylose and to the groups of amino acids and plant polymers were similar in both invaded areas and different in the non-invaded. The responses to tartaric acid, gallic acid, fumaric acid, Cistus litter, and Acacia litter were the same in long- and non-invaded areas, but different from recently invaded areas. The duration of invasion, carbon (C) content, nitrogen (N) content, C/N ratio, pH, and litter quantity explained 39.6% of the variance of catabolic responses. It is concluded that invasion by A. longifolia has substantial effects on the catabolic diversity of the soil microbial communities. These effects may have wider implications for nutrient cycling and ecosystem-level processes and for the invasibility of the system.  相似文献   

Combined effects of a simulated marine heatwave and an algal toxin on a tropical marine aquaculture fish cobia (Rachycentron canadum)     

Minh‐Hoang Le  Khuong V. Dinh  Minh V. Nguyen  Ivar Rnnestad 《Aquaculture Research》2020,51(6):2535-2544

Ongoing global warming is one of the major challenges for the development of aquaculture in the tropical regions where species are already cultured in the water temperature close to their upper physiological thresholds. Furthermore, warming can trigger blooms of toxic algae, yet we do not know how extreme warming such as a marine heatwave (MHW) and algal toxins may affect marine aquaculture species. To address this issue, we investigated the effects of a simulated MHW in combination with exposure to trans‐4‐trans‐decadienal (PUA), a diatom‐derived toxin, on survival, growth, development and biochemical composition of cobia larvae and juveniles. Cobia larvae were exposed for 48 hr to one of two temperatures (29 vs. 34°C) and two PUA treatments (0 vs. 0.5 µM). Surviving larvae from each treatment were divided into two subsets: three replicates were used for the feeding test and five replicates were used for the recovery test in a non‐contaminated environment at the respective temperatures of 29 or 34°C. Survival of cobia larvae was reduced by 16% in either MHW or PUA, but it dropped by 60% when both stressors were present, indicating a synergistic effect. MHW, but not PUA, reduced the feeding of cobia larvae. PUA had no delayed effects on growth rate and biochemical composition of the fish. MHW strongly reduced specific growth rate, body protein and lipid contents in cobia. Our results provide the first empirical evidence of how MHW and toxic algae may interact and challenge cobia and marine aquaculture production in tropical countries.  相似文献   

Ecology, history and silviculture of Scots pine (Pinus sylvestris L.) in western Norway - a literature review     

Oyen  Bernt-Havard; Blom  Hans H.; Gjerde  Ivar; Myking  Tor; Saetersdal  Magne; Thunes  Karl H. 《Forestry》2006,79(3):319-329

Results from a literature review on pinewood ecology, silviculture,genetics, aspects of history and forest resources of Scots pine(Pinus sylvestris L.) in western Norway are presented. The pinewoodscover 40 per cent of the forested land, 0.31 million ha. Duringthe last 75 years, the area has increased by 17 per cent andthe growing stock has risen from 10 to 34 million m³. The impactof man in previous times was very marked, and has had a significantinfluence on the present forest conditions. The pronounced climaticgradients mixed with the topographic variation – fromthe coastal plains via the fjord systems to the high mountains– is reflected in rather steep gradients in the pine forestvegetation. Various floristic elements can be distinguished,from oceanic via the suboceanic in the outer islands to thethermophytic, boreonemoral and boreal elements in the innerfjord districts and valleys. The introduction of spruce (Piceaspp.) plantations on 10–15 per cent of former native pineforests has not negatively affected the bird fauna at the landscapescale. Although not particular species rich, the pine forestsharbour species usually not found in other forest types. Sofar, most work in the field of silviculture and forest ecologyin the pinewoods of West Norway has been in the form of casestudies. Implications of the results for forestry in the regionare briefly discussed.  相似文献   

Willingness to pay for compulsory deworming of pets entering Sweden to prevent introduction of Echinoccoccus multilocularis     

Höjgård S  Sundström K  Christensson D  Hallgren G  Hjertqvist M  Wallensten A  Vågsholm I  Wahlström H 《Preventive veterinary medicine》2012,106(1):9-23

To investigate if the Swedish entry rules for pets to prevent the introduction of Echinococcus multilocularis (EM) are proportional (i.e. that their costs do not exceed the value of their benefits), a dichotomous-choice contingent valuation study was conducted. The study was performed before the first case of EM was detected in Sweden in February 2011. About 5000, randomly selected, Swedish citizens were invited to participate and 2192 of them (44%) accepted to do so. Missing information on whether or not one would accept to pay for keeping the rules for 143 respondents resulted in 2049 observations (41%) available for the estimation of willingness to pay (WTP), and missing information on personal characteristics for another 274 respondents reduced the number of observations available for sensitivity analysis to 1775 (36%). Annual expected WTP for keeping the rules ranged between € 54.3 and € 99.0 depending on assumptions about compensations demanded by respondents not willing to pay. The estimates are conservative since only answers from respondents that were absolutely certain they would pay the suggested bid were regarded as yes-responses. That WTP is positive implies that Swedish citizens perceived the benefits of the rules to be larger than their costs.  相似文献   

Long‐term Growth Study of Male and Female Green Sea Urchins,Strongylocentrotus droebachiensis,under Constant Light and Temperature Regime     

Sten I. Siikavuopio  Philip James  Bjrn‐Steinar Sther 《Journal of the World Aquaculture Society》2014,45(4):481-486

Juvenile green sea urchins, Strongylocentrotus droebachiensis, with an initial mean test diameter of 9.5 mm (±1.2 SD) were held in the laboratory, in individual compartments and at constant temperatures (8.5 C) (n = 90) for a period of 99 wk. The animals were supplied with flow‐through sea water, and fed the Nofima sea urchin manufactured feed ad libitum. Growth, survival, feed intake, feed conversion ratio (FCR), and gonad index (GI) of the sea urchins were monitored during this period. The mortality was 11% throughout the experimental period. The test diameter (TD) increased significantly with time, best described by a polynomial equation (TD = 0.8756 + 0.584Time − 0.002Time², R² = 0.995). Sex was included as dummy variable, but did not contribute significantly; hence, there were no differences in growth trajectories between males and females. The study showed there were no significant differences in body wet weight or FCR between males and females. However at the end of the experiment the female urchins had a significantly higher GI of 31.1% (±4.4), compared with the male urchins which had an average GI of 26.8% (±5.4). In conclusion, the present study showed that male and female green sea urchins have the same growth capacity and feed convention ratio but by the end of the experiment the gonad index was significantly higher in female than male urchins.  相似文献