Pen rearing and Imprinting of Fall Chinook Salmon, 1994 Final Report.

Results of rearing upriver bright fall chinook salmon juveniles in net pens and a barrier net enclosure in two backwater areas and a pond along the Columbia River were compared with traditional hatchery methods. Growth, smoltification, and general condition of pen-reared fish receiving supplemental feeding were better than those of fish reared using traditional methods. Juvenile fish receiving no supplemental feeding were generally in poor condition resulting in a net loss of production. Rearing costs using pens were generally lower than in the hatchery. However, low adult returns resulted in greater cost per adult recovery than fish reared and released using traditional methods. Much of the differences in recovery rates may have been due to differences in rearing locations, as study sites were as much as 128 mi upstream from the hatcheries and study fish may have incurred higher mortality associated with downstream migration than control fish. Fish reared using these methods could be a cost-effective method of enhancing salmon production in the Columbia River Basin