Random Movement and Orientation in Pink Salmon (Oncothynchus gorbuscha) Migrations

The homing migration of pink salmon (Oncorhynchus gorbuscha) from the open ocean towards their natal rivers was studied by a mathematical model using data from tagging experiments. In this model fish migration was considered to be the resultant of fish orientation and random movement. The mean migration speed and dispersion coefficient (an index of random movement) evaluated from regression analysis were 19.6 km∙d−1 and 739 km2∙d−1 for the North American group and 47.1 km∙d−1 and 863 km2∙d−1 for the East Kamchatkan group, respectively. The results indicated that pink salmon migration has more oriented movement than had been suggested by a previous computer simulation by other workers. The results also indicated that there is a distinct difference in the migratory behavior of North American and East Kamchatkan pink salmon.