Tagging experiments with salmonids

In order to find an efficient method for marking fish a tagging experiment has been carried out at the Fish Breeding Experimental Station, Sunndalsøra, Norway. Three different methods have been tried: jaw-tagging, cold-branding and tattooing with two different types of dye. During the winter 1972/1973 relatively large numbers of rainbow trout (12 602), sea trout (2 065) and salmon (13 141) were marked using the three marking methods mentioned. It was found that cold-branding with liquid nitrogen was the most rapid and inexpensive method for marking salmonids; after about one year between 87 and 92% of the fish can be identified.For cold-branding rainbow trout and sea trout an exposure time of 3 sec is too long.Tattooing with fluorescent pigments gave poor results in this experiment but could be a useful method for marking salmonids if a device could be constructed that tattoos bigger spots.Fast blue is not recommended for marking fast-growing salmonids.     

An Intensive Approach to Atlantic Halibut Fry Production

The larval stage is regarded to be the main bottleneck of halibut production. Halibut eggs were obtained from captive broodstock both by stripping and by natural spawning. Artificial photoperiods were used to increase the total spawning season. Yolk sac larvae are presently produced either in small stagnant units or in large flow through systems. A major consideration is to avoid stress of the larvae, caused by mechanical disturbances of the larvae and by high bacterial load or high ammonia levels in the water.
The experiments showed that halibut larvae began to ingest algae earlier than rotifers Brachionus sp. Supplementation of algae to first feeding tanks resulted in enhanced survival and growth rate of the larvae. Both rotifers and Artemia can be enriched with very high levels of highly unsaturated n-3 fatty acids (n-3 HUFA). Enriched live feed, containing high levels of n-3 HUFA and total lipids, enhanced both survival and growth of the halibut larvae. The highest growth rates were obtained with wild zooplankton and addition of algae, but enriched cultivated feed combined with algae resulted in growth of the same magnitude as with wild zooplankton.     

Evaluation of Old Potato Late Blight Forecasting Rules During 1994-1999 in Fields with the New Phytophthora infestans Population in Norway

Experiments were conducted to evaluate potato late blight forecasting models in Norway during 1994-1999. Various adjustments of the Førsund rules (FØR) and the NEGFRY model were compared with routine fungicide applications. In the small plot experiments ( n =25) only the fungicide fluazinam was used, but in the large plot experiments ( n =13) several fungicides were included according to farmers' practice. A total of seven cultivars were included in the experiments, Beate and Saturna being the principal ones. Generally, fungicide treatments applied in accordance with the straightforward FØR provided acceptable control of leaf and tuber blight. Using forecast techniques, the number of treatments was reduced by 25-50% compared to routine treatments without causing significantly more disease. There were no significant differences in late blight control and treatment frequency between forecasts based on FØR, using historical weather data, and NEGFRY, using historical weather data and weather prognoses. The implications of the new pathogen population, cultivar resistance and farmers' acceptance of fungicide application being related to use of forecasts are discussed.     

Focused identification of germplasm strategy (FIGS) detects wheat stem rust resistance linked to environmental variables

Recent studies have shown that novel genetic variation for resistance to pests and diseases can be detected in plant genetic resources originating from locations with an environmental profile similar to the collection sites of a reference set of accessions with known resistance, based on the Focused Identification of Germplasm Strategy (FIGS) approach. FIGS combines both the development of a priori information based on the quantification of the trait-environment relationship and the use of this information to define a best bet subset of accessions with a higher probability of containing new variation for the sought after trait(s). The present study investigates the development strategy of the a priori information using different modeling techniques including learning-based techniques as a follow up to previous work where parametric approaches were used to quantify the stem rust resistance and climate variables relationship. The results show that the predictive power, derived from the accuracy parameters and cross-validation, varies depending on whether the models are based on linear or non-linear approaches. The prediction based on learning techniques are relatively higher indicating that the non-linear approaches, in particular support vector machine and neural networks, outperform both principal component logistic regression and generalized partial least squares. Overall there are indications that the trait distribution of resistance to stem rust is confined to certain environments or areas, whereas the susceptible types appear to be limited to other areas with some degree of overlapping of the two classes. The results also point to a number of issues to consider for improving the predictive performance of the models.     

Assessing 3D point clouds from aerial photographs for species-specific forest inventories

In this study we assessed the potential of using photogrammetric data for species-specific forest inventories. The method is based on a combination of Dirichlet and ordinary linear regression models. This approach was used to predict species proportions, main tree species, total, and species-specific volume. Structural and spectral variables were used as predictors. The models were validated using 63 independent validation stands. The results from airborne laser scanning (ALS) data combined with spectral data and photogrammetric data obtained using aerial imagery with different forward overlaps of 80% and 60% were compared. The best photogrammetry-based models predicted species proportions with a relative root mean square error (RMSE) of 21.4%, classified dominant species with 79% accuracy, predicted total volume with relative RMSE of 13.4%, and predicted species-specific volume with relative RMSE of 36.6%, 46.5%, and 84.9% for spruce, pine, and deciduous species, respectively. The results were similar for the three point cloud datasets obtained from aerial imagery and ALS and the accuracies of the predictions were comparable to methods used in operational FMI. The study highlights the effectiveness of forest inventories carried out using photogrammetric data, which – differently from ALS, can include species-specific information without relying on multiple data sources.     

Experimental infection of ponies with Borrelia burgdorferi by exposure to Ixodid ticks

Seven specific-pathogen-free (SPF) ponies, 1-5 years old, were exposed to Borrelia burgdorferi-infected adult ticks while being treated with dexamethasone over 5 consecutive days. One SPF pony (pony No. 178) was first exposed to laboratory-reared nymphs without B. burgdorferi infection and 3 weeks later was exposed to B. burgdorferi-infected adult ticks with concurrent dexamethasone treatment for 5 consecutive days. Four uninfected ponies treated with dexamethasone, exposed to laboratory-reared ticks without B. burgdorferi infection served as uninfected controls. Clinical signs, bacteriologic culture, polymerase chain reaction (PCR) for bacterial DNA, immunologic responses, and gross lesions and histopathologic changes were investigated during the experiment or at necropsy 9 months after tick exposure. In all of the seven challenged ponies, infection with B. burgdorferi was detected from monthly skin biopsies and various tissues at postmortem examination by culture and by PCR. However, pony No. 178 exposed to laboratory-reared nymphs (without B. burgdorferi infection) and challenged with B. burgdorferi-infected adult ticks 2 months later did not develop a B. burgdorferi infection. All of the infected ponies seroconverted. Control ponies and pony No. 178 were negative by culture, PCR, and serology. Except for skin lesions, we failed to induce any significant histopathologic changes in this study. This is the first report of successful tick-induced experimental infection in ponies by exposure to B. burgdorferi-infected ticks. This Lyme disease model will be very useful to evaluate efficacy of vaccines against the Lyme agent and the effect of antibiotic therapy on horses infected with B. burgdorferi.     

Complete diallel cross between five strains of Atlantic salmonCroisement diallèle complet entre cinq souches de saumon de l'AtlantiqueVollständige diallele paarung zwischen fünf herkünften des Atlantik- lachses

The effect of cross-breeding on survival, growth and maturity when crossing five Norwegian strains of Atlantic salmon has been investigated. A diallel cross including purebred strains and their reciprocal crosses was used. Additive, maternal and heterosis effects were studied. Total heterosis was partitioned into average, general and specific heterosis. Growth of maturing and immature males and females was also considered.Significant total heterosis was found for survival of fry, survival of fish after marking (marked at one year of age), body weight of fingerlings and body weight of adults. However, average heterosis was low for all traits. For survival of eyed-eggs, alevins and fingerlings, dressing percentage and maturity, total heterosis was not significantly different from zero.It is concluded that cross-breeding Norwegian strains of Atlantic salmon seems to have little practical significance in a future breeding program.     

Determination of the relationship between sperm morphologic classifications and fertility in stallions: 66 cases (1987-1988)

The analysis of breeding records and sperm morphologic classifications from ejaculated semen during 99 stallion seasons, over a 2-year period, revealed a significant correlation (r = 0.34, P less than 0.01) between the percentage of morphologically normal sperm in ejaculates and the per cycle fertility estimate of the stallions studied. In addition, the percentage of sperm classified as having major defects (abnormal heads, proximal droplets, and abnormal midpieces) was significantly inversely correlated (r = -0.36, P less than 0.01) with the same fertility estimates. Multiple variable regression demonstrated that the variation in 2 morphologic features classified as major defects, abnormal heads, and proximal droplets, accounted for the largest amount of variation in fertility. It appears that in stallions, a large percentage of ejaculated sperm with major defects or other defects in combination with major defects is associated with a larger reduction in fertility than is associated with other defects.     

Effects of diet supplementation of soya‐saponins,isoflavones and phytosterols on Atlantic salmon (Salmo salar,L) fry fed from start‐feeding

A 14‐week trial was conducted to investigate the effects of antinutritional factors (ANFs) commonly present in soybean ingredients, singly and in combination, on Atlantic salmon (Salmo salar L.) fed from start‐feeding. The experimental diets consisted of a negative control fish meal diet (FM), and a positive control diet with 167 g kg^?1 soybean meal inclusion (SBM) and four diets based on the FM diet supplemented with 2 g kg^?1 soya‐saponins (SAP), 1.5 g kg^?1 isoflavones (IFL), 0.3 g kg^?1 phytosterols (PHS) or a mixture of these (MIX). Fish fed the SAP diet showed significantly higher growth performance than those fed FM, while the IFL treatment significantly decreased growth performance of salmon fry. Fish fed the IFL diet had significantly lower maltase activity and higher trypsin activity in proximal intestine than fish fed the FM diet. Histological differences were observed in the liver of fish fed the IFL diet, characterized by reduced size of the hepatocytes. Fish fed the PHS and IFL diets showed the highest frequencies of skeletal deformities among the six treatments. In conclusion, the results indicate that purified isoflavones may negatively affect growth performance, intestinal function, liver metabolism and bone formation of salmon fry.     

A forest optimisation model including carbon flows: Application to a forest in Norway

We analyse which management to choose in order to increase the carbon benefit from the 1.342 million ha forest area in Hedmark County, Norway, and the cost of doing this compared to traditional profit maximising behaviour. The model used in the analysis is a dynamic forest management optimisation model which includes the main carbon flows and benefits from the forest area: tree growth and mortality, litter accumulation, decomposition of dead wood and harvest residues, soil processes, end-use of wood products, and saved greenhouse gas emissions from using wood products instead of more energy intensive materials and fossil fuels.