Retrospective analysis of growth in pink salmon Oncorhynchus Gorbuscha using scales: Regional variability

Results of the study on the structure of scales in pink salmon, Oncorhynchus gorbuscha performed in 1997 and 2011 in six reproduction regions on Sakhalin and Kuril islands are presented. The study revealed no statistically significant correlation between the fish body length and number of sclerites on scales, but the correlation between gain of the body length and width of intersclerite distance is significant. The latter finding allows for using the scales for studying the patterns of growth in pink salmon. Comparison of the scleritograms of the first year growth revealed statistically significant differences in the relative width of intercirculi distances in pink salmon from different reproduction regions. In all cases, the difference between the groups of sclerites characterizing fish growth in the sea coastal regions were more pronounced. The changes in configuration of the scleritogram fragments characterizing growth of the juvenile fish from the open waters of the Sea of Okhotsk suggest that isolation of the regions of active feeding of the fish of various local populations remains, to a certain extent, after migration from the sea coastal waters.