Tyler passes along this sex marker paper. A lot of work done here including experimental crosses for each species along with genotyping many fish in many populations.
The linkage between the Y-chromosomal DNA marker GH-Y (growth hormone pseudogene) and the Y-associated sex-determining locus was examined in 31 populations of Coho Salmon Oncorhynchus kisutch, 29 populations of Chum Salmon O. keta, and 14 populations of Pink Salmon O. gorbuscha from North America (British Columbia [BC] and Yukon, Canada; Oregon and Washington, USA) and Japan to examine the stability of Y-chromosome sequences in salmonids. . . .We found a strong association between GH-Y and sex in Coho Salmon (with rare exceptions seen inWashington and Oregon only), whereas the association of GH-Y and sex was weak in Chum Salmon and Pink Salmon. . . The present data suggest that the genomic organization of the salmonid Y-chromosome is highly dynamic and subject to multiple forms of sequence copy number variation at multiple loci. Whether this variation has fitness implications or is selectively neutral in populations remains to be examined.