Utility of CaM gene marker to determine the boundary between the north and south Atlantic swordfish stocks

Genetic variation at the calmodulin gene locus (CaM) was investigated for a total of 109 Atlantic swordfish (Xiphias gladius) individuals collected in 2002. We confirmed the results of previous studies which have revealed the presence of genetically distinct two swordfish stocks in the Atlantic. Forty-two of 109 individuals were collected between 10N and 20N, supposedly a boundary zone. The western sample (48W) (n=18) showed allele frequencies intermediate between the north and south stocks, and the eastern sample (28W to 37W) (n=24) showed more affinity with those of the south. Thus, the boundary zone between the north and south Atlantic stocks may shift somehow lower latitude toward west from east.