Effect of photoperiod on conditioning of the great scallop

A 45 days experiment was conducted by exposing adult scallops with empty go nads to three different photoperiod regimes under constant food and tempera ture conditions: Simulated natural/decreasing photoperiod (N), constant pho toperiod (C) and increasing photoperiod (I). At the end of the experiment t he I and C groups had significantly higher gonad indexes and larger oocyte diameters compared to the N group. No significant changes were found in the N group during the experiment. The adductor muscles and digestive glands d id not change significantly during the experiment and no differences were f ound between the groups. These results suggest that photoperiod affects ear ly rebuilding of gonads in scallops from Western Norway.