An investigation into the energetics of swimming fish with special reference to Atlantic Salmon (Salmo salar L.)
Prolonged swimming endurance curves (E, min; U, Ls-1) and maximum sustained swimming speeds (Ums, maintainable for 200 minutes) of two sizes (bodylength L, m) of Atlantic salmon (in seawater) were determined: L = 0.15m: E = 864-197U, Ums = 3.62Ls-1&61 0.543ms-1; L = 0.45m: E = 1134-464U, Ums = 2.03Ls-1 = 0.91ms-1. Two hydrodynamical models were applied to these two sizes of Atlantic salmon (in seawater), swimming at or close to Ums. Mean thrust (T) and mean power (P) values were: L = 0.15m: U = 0.69Ums, T = 0.0052N, 0.0065N, P&61 0.0019W, 0.0024W; L = 0.45m: U = 0.95Ums, T = 0.30N, 0.28N, P = 0.26W, 0.25W. Oxygen consumption rates (VO2) were measured (in seawater, L = 0.65m in freshwater) for three sizes of Atlantic salmon, and Atlantic mackerel at sustained swimming speeds (Ucritx, x, the time for which that swimming speed was maintained). VO2 (mgO2kg-1h-1) obtained (and resting VO2) were: L = 0.15m: Ucrit90 = 4.0Ls-1, VO2&61 566.7 (150); L = 0.60m: Ucrit120 = 1.4Ls-1, VO2&61 270 (55.0); L = 0.65m: Ucrit120 = 1.09Ls-1, VO2&61 185.9 (94.0); Atlantic mackerel (L = 0.35m): Ucrit60 = 2.50Ls-1, VO2 = 270. Maximum sustained muscle power output (Pms) calculated from specific power output values (Wkg-1) from the literature, for estimated red muscle masses (MR) of Atlantic salmon and Atlantic mackerel were: L = 0.15m (body mass M = 25g): MR&61 1.44g, Pms-0.0070-0.12W; L = 0.45m (M-750g): MR = 25-30g, Pms&61 0.125-0.25W; L = 0.60m (M = 2000g): MR = 68.2g, Pms&61 0.34-0.55W; Atlantic mackerel (M = 413-420g): L = 0.35m, MR = 23-25g, Pms = 0.12-0.20W. All of the red muscle mass is assumed to be active when the fish is swimming at Ums. These Pms values agree well with hydrodynamical and oxygen consumption estimates of power output at Ums.