Isogenic (clonal) fish lines provide a useful experimental model in aquaculture research to study fundamental effects of rearing environment and genetics on commercially important traits. Moreover, established c lonal lines of interest can be maintained for generations without genetic change. This can provide an advantage over using variable and random genetic material of domesticated or wild origin prone to generational changes. Furthermore, higher individual variation in outbred fish groups makes it more difficult to interpret to what extent phenotypic outcomes are the result of genetics relative to environmental factors.
At the Matre Research Station in Norway, clonal lines of cultured Atlantic salmon (Salmo salar ) have been established using two-generational gynogenetic techniques. These are now being used for various fundamental and applied research purposes.
In this presentation we report on experimental work with clonal diploid, triploid, and homozygous (inbred) Atlantic salmon , as well as an identical clonal diploid group incubated at a lower temperature (4 °C instead of 8°C).
We used intermittent-flow respirometry to measure metabolic rates, hypoxia tolerance, th e acute stress response, and subsequent stress recovery. Then we assessed the morphology of hearts and otoliths since these are known to be influenced by both environment and genotype. Finally, confirmation of clonal status, ploidy, and zygosity was achieved from microsatellite markers.
The low incubation temperature slowed down development and growth, and this group was therefore tested 9 months later than the other groups to allow for it to reach a similar size of ≈170 g . Further, the low temperature group developed a clear bimodal size distribution where one-third of the group were substantially smaller.
Group differences, c auses for individual variations, and other patterns in the data will be discussed, including links between morphological and physiological traits. We conclude with our perspective o n clonal Atlantic salmon in aquaculture research.