Witch flounderGlyptocephalus cynoglossusare distributed throughout Northwest Atlantic Fisheries Organization statistical subdivision 3Ps. However, the highest concentrations are found along the southwest edge of St. Pierre Bank and in the mouths of Hermitage and Fortune bays of Newfoundland. Witch flounder are most abundant at depths of 201–300 m, although substantial numbers have been caught down to 500 m. Beyond 500 m, abundance declines considerably. The preferred bottom temperature appears to be in the range of 3.1–7.0°C, and few fish are caught outside this range. I observed significant changes in mean size and age over varying depth and temperature ranges. There have been substantial changes in age composition, growth, and maturation since commercial exploitation began in the early 1950s.