Parr–Smolt Transformation in Female and Sexually Mature Male Anadromous and Nonanadromous Atlantic Salmon,Salmo salar

The parr–smolt transformation was compared in cultured Newfoundland male and female anadromous and nonanadromous Atlantic salmon, Salmo salar. Seasonal patterns of decreasing total lipid content and condition factor accompanied by increasing moisture content, silvering, and branchial Na+-K+ATPase activity indicate that smoltification occurred only in immature anadromous females. Previously mature anadromous males did not smoitify. In general, smoltification did not occur in nonanadromous salmon. Chloride cell length did not increase in any group with smoltification. The lack of smoltification in previously mature male parr of anadromous stock is consistent with reports of small numbers of male salmon in smolt runs in many Newfoundland rivers.