Power requirement of swimming in chinook salmon and Atlantic salmon and implications for food conversion and growth performance

Body dimensions and swimming speeds of Atlantic salmon (Salmo salar) and chinook salmon (Oncorhynchus tshawytscha), ranging in weight from less than 1 to over 6 kg, were used to calculate the power needed to overcome drag. Fish were kept in 15 m x 15 m x 15 m deep cages, stocked under typical industrial conditions and fed to apparent satiation by broadcasting feed over the water surface. The average swimming speed for both species was 0.68 m s(-1). Power required for swimming increased as the fish grew, and at a weight of similar to 1.25 kg, fish changed from using available energy for long distance travelling to carrying a greater amount of weight for a shorter distance. The average profile drag acting on chinook salmon was significantly higher than on Atlantic salmon, principally because the girth of a chinook salmon was significantly larger than the girth of an Atlantic salmon of similar mass. This difference in energy expenditure due to drag explains over 20% of the observed difference in the feed conversion ratios of the two species. The selection of fish with a more streamlined body shape as breeding stock could improve the economics of chinook salmon cultivation. The techniques outlined herein can be used (a) to evaluate suitability of other species and sites for aquaculture, (b) as criteria in a breeding program, and (c) for setting criteria for permissible Velocities in fisheries projects. (C) 2000 Elsevier Science B.V. All rights reserved.