ATP content and adenylate energy charge of the mussel Mytilus edulis during the annual reproductive cycle in Lindåspollene,Western Norway

The oxygen consumption rates ( VO₂) of 6 specimens (6 to 13 kg) of the albacore tuna Thunnus alalunga were measured at sea, using specimens collected 300 km west of San Diego, California (USA) during July and August, 1981. Fish were tested in a closed continuous-flow respirometer, where they swam at about 1.3 body lengths s^-1 velocity in 15° to 19°C water. The albacore tuna is a temperate pelagic species experiencing water temperatures from about 10° to 20°C and attaining a maximum weight of 45 kg. The VO₂ ranged from 1 249 to 3 336 ml h^-1 (the mean VO₂ for the 6 fish was 2 228 ml h^-1); such values approach those of mammals of a similar size and are 3 to 4 times those of most active fishes (e.g. sockeye salmon). Among fishes, the only higher VO₂ values yet recorded were for the skipjack tuna Katsuwonus pelamis, a tropical species. The remarkably high metabolic rates of tunas are presumably correlated with their continuous swimming activity and the maintenance of endothermy. The exponent relating VO₂ to body weight (1.18), although large, is not statistically different from the exponents for most other active vertebrates.