Sea migration patterns of stocked anadromous European whitefish (Coregonus lavaretus (L.)) fingerlings

From 1995 to 1998 nearly six million one-summer old anadromous European whitefish (Coregonus lavaretus (L.)) fingerlings were marked with fluorescent pigment spraying technique. Mean total length of the stocking groups varied from 88 to 116 mm. The fish were released in the middle and northernmost parts of the Gulf of Bothnia. The stocked individuals were sampled from the sea mainly from the by-catch of the Baltic herring (Clupea harengus) fisheries. The movement patterns of the stocked fish were monitored, since growth and survival depend on their migration to southern feeding areas. The fingerlings started the feeding migration to the south irrespective of the stocking location. This migration pattern is similar to that observed in marked adult anadromous whitefish. A part of the stocked fish started migration immediately after stocking, whereas others were recaptured close to the stocking place almost one year after stocking. The longest observed migrations were several hundred kilometers.