Pug-headedness in the farmed triploid Atlantic cod, Gadus morhua Linnaeus, 1758 (Actinopterygii: Gadiformes: Gadidae) in Norway

Abstract

      A farmed triploid pug-headed specimen of the Atlantic cod, Gadus morhua measuring 501 mm TL was obtained from IMR Parisvatn Field Station, Norway. The abnormal specimen had the following aberrant characters: short neurocranium and upper jaw, very short snout in comparison with the normal specimens, and asymmetrical upper and lower jaws. The right side of the head and the pre-maxilla were deformed, twisted downward and forward. The lower jaw was slightly distorted to the left. Causes for such aberrations are discussed.