Abstract
Routine oxygen consumption ( M o 2 ) was 35% higher in 1 day starved and 21% higher in 4 day starved adult transgenic coho salmon Oncorhynchus kisutch relative to end of migration ocean‐ranched coho salmon. Critical swimming speed ( U crit ) and M o 2 at U crit ( M o 2max ) were significantly lower in 4 day starved transgenic coho salmon (1·25 BL s −1 ; 8·79 mg O 2 kg −1 min −1 ) compared to ocean‐ranched coho salmon (1·60 BL s −1 ; 9·87 mg O 2 kg −1 min −1 ). Transgenic fish swam energetically less efficiently than ocean‐ranched fish, as indicated by a poorer swimming economy at U crit ( M o 2max ). Although M o 2max was lower in transgenic coho salmon, the excess post‐exercise oxygen consumption (EPOC) measured during the first 20 min of recovery was significantly larger in transgenic coho salmon (44·1 mg O 2 kg −1 ) compared with ocean‐ranched coho salmon (34·2 mg O 2 kg −1 ), which had a faster rate of recovery.