Oxygen consumption rate and swimming efficiency of the blacknose shark, Carcharhinus acronotus

Oxygen consumption rates and swimming efficiency of 10 blacknose sharks (47 -87 cm total length and 0.45-3.51 kg weight), Carcharhinus acronotus, were determined using a closed, circular respirometer, Swimming speed ranged fro m 20-40 cm sec(-1) and averaged 30.8 (+/- 0.48 SE) cm sec(-1). Routine weig ht specific oxygen consumption rates increased from 278.5 mg 0(2) kg(-1) h( -1) for a 3.5 kg shark to 486 mg 0(2) kg(-1) h(-1) for a 0.8 kg shark. The relationship of swimming speed and weight specific oxygen consumption rate for sharks: 0.45-0.85 kg was described by the equation log V0(2) = 0.007 U + 2.38, r(2) = 0.31, P = 0.006, where U is swimming speed in cm sec(-1). Me an standard metabolic rate, the amount of oxygen consumed at zero activity, was calculated by extrapolating to zero swimming speed and was 239.8 mg 0( 2) kg(-1) h(-1), Total cost of transport (cal g(-1) km(-1)), the energy req uired to travel a given distance at a particular speed, was used as a measu re of overall swim efficiency, Highest total cost of transport (1.68 cal g( -1) km(-1)) was at 25 cm sec(-1) and decreased with increasing speed. Swimm ing efficiency was optimal at speeds of 36-39 cm sec(-1), Results suggest b lacknose sharks have higher routine oxygen consumption rates and total cost of transport, but the cost of locomotion was similar to other active, trop ical sharks.