Reference

Abstract

Five ecologically different whitefish forms were stocked in Lake Vuokalanjärvi in eastern Finland to establish dense populations and to analyse competition between different forms. Altogether, 213 253 whitefish were tagged with coded wire tags (microtags) injected into their snouts in 1987±1988. The morphologically highly similar whitefish forms have different gill-raker count distributions, but distributions overlap. In 1989±1992, 12 755 tagged whitefish were recaptured and the codes of the microtags were identified. In this study a growth model was applied to analyse and compare growth rates of different whitefish forms. The model was based on annual length increments. Differences in both the length increments in the youngest age-group and also the annual decline in length increments of different forms were statistically significant (F-test, p<0.0001). Whitefish forms with dense gill-rakers had the greatest growth rates.

Tag

Coded Wire Tag (CWT)

Objective