Morphological differentiation of the pikeperch Stizostedion lucioperca (L.) populations from the Yugoslav part of the Danube

Abstract

In order to analyse the intra- and interpopulation homogeneity/heterogeneity of thepikeperch (Stizostedion lucioperca), the phenotypic variability of morphological char-acters was estimated on the basis of a biometric analysis of 31 morphometric and 10meristic characters in 284 specimens collected at four different sections along the Yu-goslav sector of the Danube, during 1986–1989. An ANCOVA of morphological char-acters, with fish size as a covariate, was performed for analysed samples and betweenmales/females and adults/juveniles respectively. Comparison was also made with thepikeperch samples from the Dnepr and the West Dvina (Zhukov 1965). The resultswere tested with a GT2-method for multiple unplanned comparison of means, or with at-test where appropriate. The differentiation between populations from three geographi-cally distinct and isolated areas (Danube–Dnepr–Dvina) is much greater than betweenthe four samples from the Danube. The results of the variability analysis of morpho-logical characters and known pikeperch habits (first of all having in mind the so-called“homing” effect — returning to the same spawning place from year to year), suggestthat the four samples from the Yugoslav part of the Danube most probably representfour distinct populations. The presence of reproductive isolation still has to be provedthrough experimental marking. Since this analysis takes into account only the phenotypicvariation, it would be necessary to study the genetic differentiation between populations,as well, by biochemical or DNA-sequencing methods.