Cytological studies in Atlantic salmon from Canada, in hybrids between Atlantic salmon from Canada and Sweden and in hybrids between Atlantic salmon and sea trout

摘要

Atlantic salmon, Salmo salar, from the Chaleur-Bay district in eastern Canada has the same chromosome number, 2n = 58, as Atlantic salmon from Sweden. Hybrids between salmon from Chaleur and the river Lule in Sweden also have the chromosome number 2n = 58 and form multivalents and bivalents of the same type and proportion as in Scandinavian salmon. Hence, salmon from Canada and Scandinavia are presumed to have the same origin and, therefore, may be utilized in intraspecific crosses in order to improve the different strains used for breeding on both sides of the Atlantic. Hybrids between Atlantic salmon and sea trout have chromosome numbers around 2n = 69. In the meiosis rodshaped units only, and no rings, are formed together with a high number of univalents. Thus, apparently, reciprocal translocations have caused the occurrence of multivalents in the meiosis of salmon and not autopolyploidy as was earlier assumed.