Tagging juvenile European whitefish (Coregonus lavaretus (L.)) with passive integrated transponders-Impact of fish size on growth performance and tag retention

The study examined the effect of PIT tagging and size on the growth, survival, food conversion, tag retention and wound healing in juvenile European whitefish. Three size classes of juvenile whitefish (class Sbody weight (b.w.) approx. 4.0g; class Mb.w. approx. 8.0g; class Lb.w. approx. 13.6g) were tagged with PIT implanted intraperitoneally (TROVAN((R)), United Kingdom). These groups formed S-P, M-P and L-P respectively. Fish from the control groups (groups S-C, M-C and L-C) were not tagged. Whitefish from the tagged and control groups were reared for 28days in recirculating aquaculture systems. Only in the fish from the smallest group (group S-P) was tagging confirmed to have a negative impact on growth rate and survival, which, after 28days, was 70% in comparison with 94.4% in group S-C. The rate of wound healing in all whitefish groups was similar. After 28days following PIT implantation, all wounds were healed. Short-term PIT retention (28days) for all the groups was > 90%, and no differences were noted among groups. In summary, it is recommended that whitefish be PIT-tagged using the intraperitoneal method after they have attained a body weight > 8g. Tagging smaller specimens of this species leads to higher mortality.