The same two windows found in the FY GWAS were also associated with FW. However, from the 40 SNPs markers identified by the wssGWAS, only 12 explained a proportion equal to or greater than 0.1% and of them, nine were in a gene (exon or intron, Table 4). An extended list of all the SNP markers is provided in Table S3. Similar to FY, no major QTL was detected for FW which supports the polygenic architecture of FW. Three of the 12 SNPs were also located in scaffold_516 within the Calsyntenin-1-like isoform x2, Properdin and Transmembrane protein 201-like genes (Table 4). Three additional SNPs were located in scaffold_347 in the Src-like-adapter 2; Serine/ threonine-protein kinase sbk1-like; and Phd finger protein 20-like isoform x3 genes. Briefly, Src-like-adapter 2 is an adaptor protein that regulates T and B cell maturation and development, and it is a critical component regulating signal transduction in immune and malignant cells (Sosinowski et al., 2001; Dragone et al., 2006; Kazi et al., 2015). Additionally, differentially-expressed transcripts in response to handling and confinement stress in rainbow trout were mapped to a serine/threonine-protein kinase, SBK1, homologous in zebrafish that participates in signal transduction pathways related to brain development (Chou et al., 2006; Liu et al., 2015a).