Effects of inbreeding and family origin on size of chinook salmon (Oncorhynchus tshawytscha) fry

Abstract

We cultured separate lines of chinook salmon fry of Chickamin River, Southeast Alaska, ancestry in seven common garden enclosures. A parentage analysis based on variation of microsatellite alleles showed that within these lines seven brother sister matings created 35 inbred fish from 7 families (F = 0.25) and 37 outbred fish resulted from 10 matings between segregated lines. Outbred and inbred fish did not differ in length (P = 0.42), weight (P = 0.86), or condition factor (P = 0.16). There was significant variation among families for length (P = 0.01) and weight (P <0.01), but not for condition factor (P = 0.48). Because variation among families can be large, it can potentially confound the effects for which a study was designed. To avoid drawing improper conclusions, studies should estimate the amount of variation that can be attributed to family origin, or be certain that many families are sampled.