Effects of passive integrated transponder tags on survival and growth of juvenile Atlantic salmon Salmo salar

摘要

Background A laboratory experiment was conducted to assess the potential impacts of surgically implanted 23 and 32?mm passive integrated transponder (PIT) tags on survival, growth, and body condition of juvenile Atlantic salmon Salmo salar . Rate of tag retention and healing of the tagging incision were also evaluated. Atlantic salmon of three different size classes (I: 80 to 99?mm fork length (FL), II: 100 to 119?mm FL, III: 120 to 135?mm FL) were allocated to each of five experimental treatment groups: control, sham-operated (surgery without PIT-tag implantation), 23?mm PIT-tag implantation with and without suture closure of the incision, and 32?mm PIT-tag implantation without suture closure. Results Over the 35-day experiment, mortality occurred only among fish tagged with 32?mm PIT tags (14%) and all fish larger than 103?mm FL survived. Non-sutured Atlantic salmon between 80 and 99?mm FL implanted with 23?mm PIT tags had a significantly lower mean specific growth rate of mass compared with untagged (control and sham-operated) and sutured conspecifics. However, no significant difference in growth was found between untagged fish and 23?mm PIT-tagged fish 100 to 135?mm FL. Implantation of 32?mm PIT tags decreased growth in all size classes. Regardless of size class, body condition of the fish was not affected by PIT tagging. Retention rates of 23?mm PIT tags with and without suture closure were 100% and 97%, respectively; retention of 32?mm PIT tags without suture closure was 69%. At the end of the experiment, tagging incisions without suture closure were generally well-healed. Fungal infection and inflammation around the incision site occurred only when suture was used, in 46% of size class I, 21% of size class II and 38% of size class III. Conclusions Although suture closure of the incision following 23?mm PIT-tag implantation had a positive impact on growth of fish smaller than 100?mm FL, we advise against the use of sutures due to high rates of fungal infection around the incision site. Hence, results suggest that surgical implantation of 23?mm PIT tags without suture closure of the incision is a feasible method for marking juvenile Atlantic salmon 100 to 135?mm FL. Further, we caution researchers about the use of 32?mm PIT tags in juvenile Atlantic salmon 80 to 135?mm FL due to high rate of tag rejection and reduced survival and growth.