Every year, millions of adult sockeye salmon (Oncorhynchus nerka) perform an arduous, once-in-a-lifetime migration up the Fraser River (BC, Canada) to return to their natal stream to spawn. The changes in heart rate, stroke volume, and arterio-venous oxygen extraction (i.e., factors determining rates of oxygen delivery to the tissues by the cardiovascular system) have never been directly and simultaneously measured along with whole animal oxygen uptake in a maximally swimming fish. Here, such measurements were made using three sockeye salmon populations (Early Stuart, Chilko and Quesnel), which each performed two consecutive critical swimming speed (Ucrit) challenges to provide a comprehensive quantification of cardiovascular physiology, oxygen status and blood chemistry associated with swimming and recovery. Swim performance, oxygen uptake, cardiac output, heart rate and stroke volume did not significantly vary at rest, during swimming or during recovery between populations or sexes. Despite incomplete metabolic recovery between swim challenges, all fish repeated their swim performance and similar quantitative changes in the cardiorespiratory variables were observed for each swim challenge. The high maximum cardiorespiratory performance and excellent repeat swim performance are clearly beneficial in allowing the salmon to maintain steady ground speeds and reach the distant spawning grounds in a timely manner.
Keywords: A-V(O2); Aerobic scope; Blood gases; C(aO2); C(vO2); COT; COT(net); COT-V̇(b); COT-V̇(bnet); Cardiac output; EPOC; Hct; Heart rate; Lactate; MCHC; Migration; Oxygen consumption; P(aO2); P(vO2); Plasma ions; RR; T(aO2); T(opt); T(vO2); U(crit); V(s); V̇(b); [Hb]; arterial blood oxygen content; arterial blood oxygen transport (T(aO2)=V̇(b)×C(aO2)); arterial blood partial pressure of oxygen; cardiac output; cardiovascular cost of transport (COT-V̇(b)=V̇(b)/(U×60)); cost of transport (COT=ṀO(2)/(U×60)); critical swimming speed; excess post-exercise oxygen uptake; f(H); haematocrit; haemoglobin concentration; heart rate; mean corpuscular haemoglobin concentration (MCHC=[Hb]/(Hct/100)); net cardiovascular cost of transport (COT-V̇(bnet)=(V̇(b)−V̇(brest))/(U×60)); net cost of transport (COT(net)=(ṀO(2)−ṀO(2rest))/(U×60)); optimal temperature for aerobic scope; rate of oxygen uptake; recovery ratio for consecutive swim challenges (RR=U(crit) 2÷U(crit) 1); stroke volume (V(s)=V̇(b)÷f(H)); tissue oxygen extraction (A-V(O2)=C(aO2)−C(vO2)); venous blood oxygen content; venous blood oxygen transport (T(vO2)=V̇(b)×C(vO2)); venous blood partial pressure of oxygen; ṀO(2).
© 2013.