Marking One-summer-old Whitefish with Fluorescent Pigment Spraying Method and Results of Whitefish Stockings in the Gulf of Bothnia

............................................................................................................. 6 Original publications ......................................................................................... 7 Introduction ........................................................................................................ 8 Gulf of Bothnia ................................................................................................. 8 Anadromous whitefish in the Gulf of Bothnia ..................................................... 9 Whitefish fingerling production ........................................................................ 10 Anadromous whitefish stocking in the Gulf of Bothnia. ................................... 11 Fish tagging and marking as a tool in whitefish studies .................................. 12 Fluorescent pigment marking ......................................................................... 14 Why to use fluorescent pigment method in estimating the Gulf of Bothnia whitefish stocking results? ............................................................................. 15 The objectives of this thesis............................................................................ 15 Materials and Methods .................................................................................... 16 Catch statistics .............................................................................................. 16 Professional fisheries ................................................................................. 16 Recreational fisheries ................................................................................. 16 Determining marking technique for one-summer old whitefish ......................... 17 Tuning the apparatus .................................................................................. 17 Stress caused by marking .......................................................................... 17 Long-time retention of the marks ................................................................ 18 Mark-recapture study of the stocked, one-summer old anadromous whitefish in the Gulf of Bothnia ......................................................................................... 19 Marking and release ................................................................................... 19 Sampling for marked whitefish .................................................................... 21 First-year survival, migration, growth and catch estimates .......................... 21 Results and Discussion .................................................................................... 23 Applying the fluorescent pigment marking method for the one-summer old whitefish ......................................................................................................... 23 Stress caused by marking .......................................................................... 24 Long time retention .................................................................................... 24 Mark-recapture study of the stocked, one-summer old anadromous whitefish in the Gulf of Bothnia ......................................................................................... 25 First year survival ....................................................................................... 25 Migrations .................................................................................................. 26 Growth, maturity and catch estimate.......................................................... 26 Conclusions ...................................................................................................... 28 Acknowledgements ......................................................................................... 29 References ....................................................................................................... 31