Survival and swimming performance of a small-sized Cypriniformes (<em>Telestes muticellus</em>) tagged with passive integrated transponders

Abstract

Italian riffle dace (Telestes muticellus, Bonaparte 1837) is a small-bodied Leuciscidae native to the Italian Peninsula, of which little is known about the ecology and individual movements in nature. Passive Integrated Transponder (PIT) telemetry is used to track fish movements and behaviour. The basic assumption is that the PIT-tagged organism's performances do not differ considerably from their natural behaviour. Here we present the first evaluation of potential tagging effects in the genus Telestes. The survival rate and tag retention were compared between two different tag implantation methods – injector gun and scalpel incision - and pit-tagging effects on swimming performance were evaluated. Five weeks after tagging, Italian riffle dace demonstrated high survival rates in all treatments: 94.8% for fish tagged with injector gun (n=58), 100% for scalpel incision method (n=58), and 98.3% for controls (n=58). The tag retention was 96.6% for gun treatment and 100% for scalpel treatment. Prolonged swimming performance, tested 22-23 days after tagging, showed a reduction in endurance (time-to-fatigue) for scalpel treatment (n=22) compared to the control group (n=21), while no difference in maximum swimming velocity was observed. We conclude that PIT tagging is a suitable technique for Italian riffle dace, showing high survival and PIT retention and no effect on maximum swimming speed. Significantly lower prolonged swimming performance, although likely less ecologically important, shows that tagging is not without costs. Potential biases need to be evaluated on a study-by-study basis, and future studies should explore behavioural tagging effects in nature.

Downstream migration of landlocked Atlantic salmon smolt in a regulated river—Effects of multiple passage at dams with programmed spill

“…We anticipated that trapping might have caused some problems for the fish as the fyke net trap was situated in fast-flowing water, up to 1 m s À1 , without any refuge from the current. Although, more subtle tagging effects cannot be excluded (Schiavon et al, 2023), the results from our procedural controls using dummy tags and untagged fish indicated that mortality due to tagging and/or trapping was low and occurred within 24 h. Our fish were held at least 30 h after tagging and only fish that looked healthy were released. As an extra precaution to avoid overestimating mortality, fish that did not initiate downstream migration within 24 h after release were excluded from the study.…”

The interplay of group size and flow velocity modulates fish exploratory behaviour

“…Despite the extensive construction of fish passages to mitigate freshwater migratory fish decline, the efficacy of these structures is debated, as numerous structures suffer from low passage efficiency 63 , 64 . An effective exploratory behaviour is crucial for fish to search and locate entrances of fishways at river barriers 63 – 65 , and while extensive research has focused on enhancing the attractiveness of such entrances for individual fish 64 , 66 , 67 , very little is known about the case of shoaling fish 17 , 68 . Emerging experimental evidence, such as studies on gudgeons ( Gobio gobio ) 69 and barbels ( Barbus barbus ) 70 , suggests that aggregation can lead to increased passage efficiency.…”

Navigating the drought: upstream migration of a small-sized Cypriniformes (Telestes muticellus) in response to drying in a partially intermittent mountain stream

“…A subsample of the Telestes muticellus greater than 6.0 cm, corresponding to a size range of fish older than 1 yr, was tagged with Passive Integrated Transponders (PIT tags; Oregon, USA; 12 Â 2.1 mm; 0.10 g). High survival and tag retention rates were reported for this species (Schiavon et al, 2023). Before tagging, fish were anaesthetised with clove oil (Aromlabs, USA; approximately 0.2 mL clove oil per litre of water).…”

“…Before tagging, fish were anaesthetised with clove oil (Aromlabs, USA; approximately 0.2 mL clove oil per litre of water). An incision of 2-4 mm was made on the ventral side of the fish, slightly offset from the centre and frontal to the pelvic fins, before the tag was inserted and pushed forward in the abdomen (Nyqvist et al, 2022;Schiavon et al, 2023). Once the fish had been tagged, they were measured for fork length and weight and allowed to recover in tanks filled with river water.…”