Stress associated with commercial longlining and recreational fishing of saithe (Pollachius virens) and the subsequent effect on blood gases and chemistry

The stress associated with commercial and recreational fishing of saithe (Pollachius virens Linnaeus) was investigated on fish caught with a rod and reel at the pier < 10 s or 4–5 min at 100 m depth and after 6–12 h of soaking on a longline or chased to exhaustion for 15 min. Results show that hooking caused an acute stress reaction accompanied by accumulating blood lactate and pCO2 levels accompanied by the acidification of the muscle. After 6–12 h of soaking, the longlined had a significant increase in blood glucose levels, Na+, K+, hemoglobin content and hematocrit values. During soaking the longlined fish had restored their acid–base balance, having significant higher blood pH and HCO3− levels, reflecting hyperventilation. Only one case of hypoxia was observed. None of the 767 investigated fish that was hauled onboard had died during soaking. We conclude that angling causes a long and short term stress effect on P. virens, but survival is related to animal capability to restore acid–base balance during soaking.

► Angling of saithe increases blood lactate and pCO2 levels.
► Accompanied by acidification of the muscle.
► 6–12 h of soaking caused disturbance of the fishes osmolarity balance.
► While soaking this specie had the capability of restoring their acid base balance.
► Enabling survival during soaking.