Impacts of VIE tagging and Rhodamine B immersion staining on two measures of performance for a small-bodied fish

Context

Passage efficiency is an important metric for quantifying the success of fish-passage remediation. Mark–recapture methods are typically employed to estimate fish-passage efficiency. Although biotelemetry methods have become a benchmark standard for such studies, they remain unfeasible for many small-bodies species because of the excessive size of electronic tags.

Aims

This study compares two commonly deployed marking methods that are potentially suitable for estimating passage efficiency for small-bodied species, namely, visible implant elastomer (VIE) tagging and batch immersion staining with Rhodamine B.

Methods

The critical swimming speeds and passage efficiency at a remediated culvert of Galaxias maculatus were compared for VIE-tagged, Rhodamine B-stained and control treatments.

Key results

Both critical swimming speeds and passage efficiency at the culvert were significantly lower in VIE-tagged Galaxias maculatus than in both control fish and fish stained with Rhodamine B.

Conclusions

Rhodamine B may be a suitable batch immersion stain for short-term (<4 day), non-destructive mark–recapture studies in small-bodied fishes, but VIE-tagging methods may result in underestimation of passage efficiency.

Implications

It is important to evaluate the impact of marking techniques on the outcomes of mark–recapture studies to ensure that estimates of passage efficiency are accurate.