Ongoing projects

Ida Vilinn Tolås
AquaDome: Effect of closed cages on salmon health.
About 20 % of the farmed salmon in Norway is lost as a result of diseases. In addition, surviving salmon, after a disease outbreak, may be downgraded due to quality. The salmon farming industry is also criticized for having a negative impact on the wild salmonids in Norway. A major focus for this criticism is the influence of the salmon louse (Lepeophtheirus salmonis) on wild salmonids. As a response to these problems the industry has developed closed and semi-closed systems for production of salmonids, and one of these systems, the AquaDome, are being tested by EWOS Innovation Dirdal. The test-project will focus on several factors (growth, fish health, behaviour, feed use, mortality, environmental parameters, etc) in a comparative study comparing the AquaDome with production in open nets. The fish were put to sea in March/April 2011 and will be harvested in February 2012. The main aim of the master thesis is to compare of prevalence and density of known salmon pathogens in the open nets and the AquaDome.

Geir Schriwer
Prevalence and densities of selected pathogens in wild populations of Atlantic salmon from five large river systems in western Norway.
Production of Atlantic salmon in Norway has for many years suffered from several diseases resulting in high mortalities. Some of the causative agents are also causing problems for wild salmonids (ex. Lepeophtheirus salmonis), and an additional number have the potential to have a negative influence on wild salmonids (ex: Parvicapsula pseudobranchicola, Paranucleospora theridion, Eubothrium sp., and Flavobacterium psychrophilum). Little has been done to see if any of these may influence on the survival and reproductive success of wild salmon and trout in Norway, but a project to gather information about the distribution, prevalence and intensity of all known salmonid pathogens that may have a negative influence on wild salmonids has been started. Wild salmonids collected in rivers in the counties Rogaland, Hordaland, Sogn og Fjordane and Møre og Romsdal in the period 2009 – 2011 are included in the study. The major focus will be on wild S. salar and some important pathogens that are frequently found in farmed populations in western Norway. A major area of focus will be the Hardangefjord area.

Arnfinn Økland
Development of Paranucleospora theridion in Lepeophtheirus salmonis.
A new microsporidian, Paranucleospora theridion, was detected in Atlantic salmon, trout, rainbowtrout and salmon lice in 2008. This microsporidian has a complex life cycle with the production of four different spores, ie.  production of two different spores in salmon and another two in salmon louse. One spore development, resulting in autoinfective spores, occurs in the cell cytoplasm of selected cells in salmon. These spores are spread within the salmon host and may cause an inflammatory response in all tissues (skin, gills, heart, kidney, spleen, pancreas etc). The second spore development occurs in the nucleus of epithelial cells of gills and skin of infected salmon. It is believed that these spores are infective stages for transmission to salmon lice (L. salmonis and Caligus elongatus).  P. theridion develops two different spores (micro- and macrospores) in salmon louse. The present study will follow the development of P. theridion in the different stages (chalimi, preadults and adults) of the salmon louse, and give a detailed description of the morphological development in these stages.