Guidelines save sharks, study reveals

Most sharks released by recreational anglers survived when recommended handling guidelines were followed, according to new research.

Scientists from the University of Exeter tagged close to 70 blue, porbeagle and tope sharks to monitor how they behaved after being caught and released by non-commercial fishers.

Catch-and-release is widely used to help support shark populations, though some animal welfare organisations argue the practice can still cause harm or even death.

The study found that of all the sharks tagged in waters off England, Scotland and the Channel Islands, only three — one from each species — died after release when best-practice procedures were used.

Post-release behaviour

The electronic tags, which stayed attached for up to 45 days, recorded movements before detaching and sending location data back to the team, which included researchers from Edinburgh Napier University and the Government of Jersey.

Sixteen tags were recovered, offering more detailed insight into diving depth and movement patterns after release.

All three shark species were seen to rapidly descend into deeper water immediately after being freed, behaviour researchers believe helps them avoid predators and re-oxygenate their gills.

Francesco Garzon of the University of Exeter said behaviour later varied between species, though sharks typically remained at greater depths for a period.

“Most individuals appeared to have recovered within 24 hours, although some sharks — particularly porbeagles — occasionally took longer,” he said.

Regarding the three deaths recorded, Mr Garzon noted these could not be linked to any specific aspect of the capture or release process. The sharks showed no obvious injuries and were active at the time they were let go, he added.