Seawater adaptability of two strains of arctic char (Salvelinus alpinus) reared under different light regimes

摘要

Groups of Arctic char (Salvelinus alpinus) were reared underthree experimental light regimes. Two different strains of charwere used, one non-migratory from south Norway, the other anadromousfrom northern Norway. All groups received a continousbackground illumination. One of the experimental light regimesconsisted only of this background illumination. The remainingtwo treatments consisted of an additional simulated natural photoperiod,using either yellow light or daylight. Growth rate wasmonitored during the experiment. A Seawater Challenge Test(SWCT) was run for 24 hours to evaluate the ability of the twostrains of char to tolerate and survive in seawater.There were no significant differences in growth rate in eitherstrain between the experimental light regimes. Condition factorincreased during the experimental period for fish of bothstrains and all light regimes. Both strains tolerated the SWCTwithout mortalities. Size seems to be the most important factorfor seawater adaptability of Arctic char. There were no signs ofa smoltification process as seen in Atlantic salmon (Salmo salar).