Genetic diversity within and among Atlantic cod (Gadus morhua) farmed in marine cages: a proof-of-concept study for the identification of escapees

• Main Authors: Glover, Kevin A., Dahle, Geir, Westgaard, Jon-Ivar, Johansen, Torild, Knutsen, Halvor, Jørstad, Knut Eirik
• Format: Article in Journal/Newspaper
• Language: English
• Published: Animal Genetics 2010
• Subjects: atlantisk torsk; atlantic cod; torskeoppdrett; cod farming; genetikk; genetics; VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Resource biology: 921; VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497; Norway; Gadus morhua
• Online Access: http://hdl.handle.net/11250/108521

Article published in Animal Genetics, 41 (5): 515-522 OCT 2010 This study presents a molecular genetic characterization of Atlantic cod reared in commercial marine farms. Samples consisted of approximately 47 fish collected from nine cages located on four farms throughout Norway. In addition, 28 farmed escapees were recaptured in the sea (443 fish in total). Nine microsatellite loci and the Pan I gene were analysed, revealing a total of 181 alleles. Each sample contained 43–63% of total allelic variation. Comparing variation with published data for wild cod indicates that lower genetic variation exists within single cages than in wild populations. Significant linkage disequilibrium was observed amongst pairs of loci in all samples, suggesting a low number of contributing parental fish. Global FST was 0.049, and the highest pairwise FST value (pooled loci) was 0.085. For single loci, the Pan I gene was the most diagnostic, displaying a global FST of 0.203. Simulations amongst the samples collected on farms revealed an overall correct self-assignment percentage of 75%, demonstrating a high probability of identifying individuals to their farm of origin. Identification of the 28 escapees revealed a single cage as the most likely source of origin for half of the escapees, whilst the remaining fish were assigned to a mixture of samples, suggesting more than one source of escapees.