Application of the alizarin red S mass marking technique and its detection in stocked asp (Leuciscus aspius)

Abstract

Alizarin Red S marking and detection was tested on asp (Leuciscus aspius Linnaeus, 1758) in an experimental pool followed by a mark-recapture experiment in the field. Placing the asp in a 0.15 g L−1 solution for one hour produced marks that were detectable for at least one year. In order to detect the fluorescent marks, novel equipment was developed comprising a battery-powered laser source (<100 mW laser pointer, wavelength 532 nm) and protective filtration goggles (filtering wavelength 190–540 nm). The detection equipment and procedure proved satisfactory for marking large numbers of fish and for detection in the field. It allowed repeat observations of the same fish and examination of fin rays (eventually fin clips), which are usually too large to examine under a standard microscope. This method is highly recommended for future studies.