Preliminary observations on induced triploidy by heat shock in northern pike (Esox lucius L.)

Abstract

Eggs of northern pike (Esox lucius L.) were submitted to heat shock shortly after fertilization. Eggs were then incubated and the hatching larvae reared until the end of the yolk-sac resorption. A heat shock at 28°C occuring 10 minutes after fertilization, which lasted for 10 minutes, resulted in the highest percentage (up to 50%) of triploid fish. Treatments applied 15 minutes after fertilization for 5,10, 20 and 25 minutes at 27-32°C gave lower percentages of triploid fish; shocks applied 5 and 25 min after fertilization did not induce triploidy.