Implementation of PIT-tags influence spatial distribution but not burst and hiding performance of a freshwater fish

Abstract

Tagging techniques, such as electronic transmitters and Passive Integrated Transponders (PIT-tags), are commonly used to monitor individuals to gather data on migration routes, habitat preferences, interactions with the environment, as well as movements in both natural and laboratory settings. However, concerns about the impact of tagging on animal welfare and behavior have been raised. This study aimed to evaluate retention rates to intramuscular and intraperitoneal tag implantation locations in chubs (Squalius cephalus). We also quantified effects of intramuscular PIT-tags on swimming performance, exploratory behavior, movement complexity and hiding behavior (in a behavioral arena), as well as stress indicators. Our study demonstrates that intramuscular PIT-tagging implementing allow a higher retention rate (97.5 %) compared to peritoneal injection (78.6 %). This result is lower than in other studies, which might be linked to species-specific differences, or colder water preventing healing and thus reinforcing tag loss. Additionally most of the measured behavioral variables did not show significant differences between intramuscularly tagged and untagged individuals. Tagged individuals still expressed reduced positioning at the center of the behavioral arena 3 weeks after tagging. This result suggests that the implantation of pit-tag could potentially affect exploration behavior and spatial distribution of fish in their environment in the short term. Longer-term effects should be considered but, according to our findings, intramuscular tagging appears to be a more reliable option for studies prioritizing long-term data collection. One may take into account the effects of these tags when computing fine-scale behavioral assessments, or should consider alternative methods.