Quantification of alizarin red S uptake in coregonid eggs after mass-marking.

An easy method to measure the uptake rate of the persistent dye alizarin red S (ARS) during marking of whitefish eggs was established and used to measure the ARS content in three different whitefish species during and at the end of the marking procedure. Those values show that only 6-10% of the ARS in the marking solution will be absorbed by the eggs (0.0061-0.0119 mg per egg). Additional analyses 6, 15 and 36 months after marking showed ARS levels below the response level (<6.9 µg kg-1 ).