Allozymic variation among populations of noble crayfish, Astacus astacus L., in southern Norway: implications for management

Abstract

Abstract. The noble crayfish, Astacus astacus L., is extensively used for stocking and restocking purposes both in Scandinavia and in other European countries. It also has potential as a farmed species. Thus, it is important to have information about the genetic structuring of the species. Attempts have been made to detect genetic variability in A. astacus and find markers suitable for interpopulation discrimination. Two loci, coding for the enzymes leucine‐aminopeptidase (LAP) and xanthine dehydrogenase (XDH), have previously been found to exhibit allele frequency differences among four recently established populations of crayfish in southern Norway. Eight more populations have now been studied for these and 13 other enzyme‐coding loci. All of the 13 additional loci examined were found to be monomorphic. The variable zymogram bands of LAP and XDH are thought to reflect genetic variation at their encoding loci. It is suggested that the significant inter‐stock allele frequency differences at these loci are to a large extent due to founder events and random genetic drift. Since information about the size and genetic characteristics of the founder populations is limited, the relative contribution of selective constraints to stock diversity cannot be assessed. For restocking strategies one should consider using both reserve populations of the original populations and other strong populations with known genetic characteristics.

Assessment of Dna Variations of the Noble Crayfish (Astacus Astacus L.) in Germany and Poland Using Inter-Simple Sequence Repeats (Issrs)

“…As stated by FEVOLDEN et al (1994), present-day Norwegian crayfish populations were most probably introduced from Sweden. Detected differences could therefore originate from genetically differentiated founders (FEVOLDEN et al, 1994). Differences between populations of A. astacus with common ancestors were most likely caused by founder effects and genetic drift (FEVOLDEN and HESSEN, 1989).…”

“…astacus had been published by FEVOLDEN and HESSEN (1989), AGERBERG (1990) and FEVOLDEN et al (1994). AGERBERG (1990) found no genetically interpretable variation in any of the four A. astacus populations sampled in Sweden and Poland, whereas HESSEN (1989) andFEVOLDEN et al (1994) observed significant intersample heterogeneity at two polymorphic loci in A. astacus populations sampled in Norway. As stated by FEVOLDEN et al (1994), present-day Norwegian crayfish populations were most probably introduced from Sweden.…”

“…AGERBERG (1990) found no genetically interpretable variation in any of the four A. astacus populations sampled in Sweden and Poland, whereas HESSEN (1989) andFEVOLDEN et al (1994) observed significant intersample heterogeneity at two polymorphic loci in A. astacus populations sampled in Norway. As stated by FEVOLDEN et al (1994), present-day Norwegian crayfish populations were most probably introduced from Sweden. Detected differences could therefore originate from genetically differentiated founders (FEVOLDEN et al, 1994).…”

“…As second step, estimations of stock size and quality in regard to diseases in combination with the assessment of genetic diversity allow the selection of appropriate donor populations within those units. To ascertain a minimum of genetic variety, strong populations with high heterozygosity or genetic variation are preferable (FEVOLDEN et al, 1994). Crayfish hatcheries could play an important role in managing the noble crayfish.…”

“…A variety of methods have been applied. Early studies based on protein electrophoresis have shown only low levels of variation between populations of European freshwater crayfish (ATTARD and VIANET, 1985;FEVOLDEN and HESSEN, 1989;AGERBERG, 1990;FEVOLDEN et al, 1994). During the last decade molecular techniques revealing a higher degree of variability have been developed and applied successfully in population studies of freshwater crayfish.…”