The blood respiratory, haematological, acid-base and ionic status of the Port Jackson shark, Heterodontusportusjacksoni, during recovery from anaesthesia and surgery: a comparison with sampling by direct caudal puncture

Abstract

The effects of caudal cannulation on the blood physiology of the Port Jackson shark, Heterodontus portusjacksoni, were investigated in sharks given between 4 and 72 h to recover from surgery. Neither the Pa O 2 – Pv O 2 difference nor the Ca O 2 – Cv O 2 difference of cannulated sharks fluctuated throughout the sampling period. The plasma acidosis exhibited 4 h after surgery was partially compensated after 24 h by a respiratory (hyperventilatory) alkalosis and after 72 h by a marked metabolic alkalosis. Whilst H. portusjacksoni exhibited some cell swelling after surgery the haematological status of cannulated sharks generally varied little throughout the recovery period. In contrast, marked changes in plasma and erythrocyte ion concentrations were indicative of increased branchial and erythrocyte ion permeability. The blood status of H. portusjacksoni given 72 h to recover from surgery was also compared with sharks sampled by caudal puncture. The respiratory and acid-base status of sharks sampled by caudal puncture was comparable to that of cannulated sharks. In contrast, the plasma ion concentrations of the cannulated sharks were markedly elevated and the erythrocyte ion concentrations concomitantly reduced when compared with punctured sharks. The apparent increase in the water and ion permeability of cannulated sharks was reflected by the reduced [Hb] and mean cell haemoglobin concentrations (MCHC). Blood sampling by caudal puncture appeared to reduce the haematological and ionic perturbations that resulted from surgery and thus provided a less invasive and reliable method for obtaining samples from ‘non-disturbed’ elasmobranchs.