Development evaluation of methods for osmotic induction marking of golden perch macquaria ambigua with calcein and alizarin red S

Abstract

We conducted a series of osmotic induction procedures for marking golden perch Macquaria ambigua with calcein and alizarin red S (ARS), evaluated the factors that influenced mark quality, and tested for any effects on fish growth and mortality. Three aspects of the marking protocols were considered: immersion time in a 5% salt solution (0, 5, or 10 min), immersion time in the fluorescent dye (5 or 10 min), and concentration of the dye (low or high). Quantitative estimates of mark intensity using photographs of marked fish were made with image analysis software. Although there were some significant interactions between factors, salt immersion was generally the primary determinant of mark intensity, followed by dye concentration and dye immersion time. Fish marked with calcein did not have higher mortality rates than unmarked fish and had significantly higher growth rates. The highest-exposure ARS treatments resulted in higher mortality and lower growth rates than for unmarked fish. Following this result, a lower-exposure ARS marking protocol was tested, which resulted in no detectable effects on mortality or growth rates while still producing high-quality marks. Although further study of the long-term retention of marks under field conditions is required to understand the limitations of the chemical marking methods examined in this study, our results suggest that the methods would greatly enhance our knowledge of the outcomes of fish stocking.