Heritability of fluctuating asymmetry for multiple traits in chinook salmon (Oncorhynchus tshawytscha)

The heritability of fluctuating asymmetry (FA) as an indicator of developme ntal instability is of interest to evolutionary and conservation biologists and is the subject of ongoing controversy. This study examined the inherit ance of FA in two groups of fish: domestic chinook salmon (Oncorhynchus tsh awytscha) mated in a full-sib design and domestic and wild chinook salmon m ated in a half-sib design. Eight traits were measured on the right and left sides of each fish: eye diameter, head length, maxillary length, branchios tegal ray number, pectoral and pelvic fin ray number, and upper and lower g ill raker number on the first gill arch. Narrow-sense heritabilities were c alculated from parent-offspring regressions for the first group and using s ib analysis for the second group. Our data represent the largest breeding p rogram designed to detect heritability of FA in fish reported to date. We f ound no significant heritability of FA for any of the individual traits exa mined or for a composite FA index. Our results indicate that FA estimates i n chinook salmon will not be confounded by appreciable additive genetic con tributions and thus can be reliably used as an environmental and genetic st ress indicator.