Fishing may be cruel even if the fish are thrown back in the water, because they subsequently struggle to feed, according to a new study.
“Catch-and-release” policies have become the norm on many British rivers and lakes in recent years, considered a more human method and vital for conserving stocks.
But scientists now believe that hooking fish such as salmon and trout injures their mouths so that they become less able to suck in prey.
In the first study of its kind, researchers monitored 20 shiner perch caught from the wild in Canada.
Half had been hooked and half caught in a net.
When they were observed using high-speed cameras in a controlled environment, those that had been hooked fed significantly less well.
The scientists at University of California Riverside believe this is because the hole caused by the hook disrupts the suction system, which works similar to how humans suck fluids through as straw.
“As we predicted, the fish with the mouth injuries exhibited a reduction in the speed at which they were able to draw prey into their mouths,” said Professor Tim Higham, who led the research.
“This was the case even though we used barbless hooks, which are less damaging than barbed hooks.