Aquaculture Canada OM 2011 38 AAC Spec. Publ. No. 20 Production of sterile Atlantic cod: A way to satisfy industrial and environmental criteria? S. Peruzzi 1 , I-B. Falk Petersen 1 , I. Lein 2 , V. Puvanendran 3 , Ø. Hagen 4 , M. Jobling 1 1 Department of Arctic and Marine Biology Faculty of Biosciences, Fisheries and Economics University of Tromso, Breivika 9037 Tromsø, Norway. Tel.: (0047)77646798; Fax: (0047)644900; E-mail: Stefano.Peruzzi@uit.no 2 Nofima Marin, 6600 Sunndalsøra, Norway 3 Nofima Marin, 9291 Tromsø, Norway 4 Seafood Quality Group, Faculty of Biosciences and Aquaculture, University of Nordland, 8049 Bodø, Norway Abstract The production of sterile triploid fish may be a viable option to tackle the problems of precocious sexual maturation and the genetic impact of farmed fish escapees in cod farming. This could meet both indus- trial and environmental criteria. In this work, the effects of triploidy on growth, body traits, muscle fibre distribution, and fillet quality characteristics are described. Three-year-old triploid cod had approxi- mately 18% fewer pyloric caeca and a 23% shorter gut than their diploid siblings. Also, triploidy resulted in improved post-harvest production traits, such as higher protein content and reduced fillet gaping. Overall, there appear to be advantages associated with adopting farming technologies that involve the induction of triploidy in Atlantic cod. Introduction Atlantic cod (Gadus morhua L.) is an important species for the diversification of the aquaculture industry in North Atlantic countries but its farming has proven challenging. Unresolved issues that are having an influence on the development of cod farming include precocious sexual maturation and farmed fish escapes. Pre-harvest sexual maturation is of concern because it results in increased mortal- ity, reduced growth and poorer flesh quality. The escape of cod from farms not only represents an economic loss for producers but it might also have ecological and genetic impacts on wild fish. The farming of sterile cod may be an option both for reducing the incidence of early maturation and for reproductive containment of farm escapees. The production of triploid fish could be a method for inducing sterility. Triploid cod can be reared to market size and there is evidence of gametic steril- ity in males (1,2) but little is known regarding their culture performance and body traits. In this work, we analyze the gut morphology and flesh quality characteristics of diploid and triploid cod sib- lings raised under communal rearing conditions. Materials and Methods Fish originated from a mixed ploidy group held under ambient light and temperature conditions (69°N, 19ºE). The group was composed of n = 20 individually PIT-tagged diploid and certified triploid siblings produced as described in Peruzzi et al. (1). Briefly, fish were raised communally in indoor tanks supplied with flow-through sea- water and fed to satiation using a commercial diet for marine fish (Skretting, Norway). They were measured for standard length (SL) and body weight (BW) at three-month intervals. In June 2009 (age = 38 months) the fish were sacri- ficed and measured for growth (body weight, standard length), gut length (Relative Gut Length or RGL), pyloric caeca number, muscle fibre diameter (3) and flesh quality traits. Data on py- loric caeca number and RGL were analyzed by t- test. Texture measurements were performed in-