Catch-and-release fishing damages the fish’s feeding ability

Catch-and-release fishing might seem much more humane than traditional fishing, but a new study has found that the hole left by a fishhook damages a fish’s feeding ability.

Researchers from the University of California-Riverside conducted a study to examine catch-and-release fishing, which although touted as a conservational fishing practice, could be doing unnecessary damage to at-risk species of fish.

The study was published in The Journal of Experimental Biology.

Salmon, bass, and trout, all sought after species in sport fishing, use a method called suction feeding where a fish will rapidly expand its mouth and suck in prey. The sucking generates pressure in the fish’s mouth which is how the prey is drawn in.  

The researchers wanted to examine how a hole left by a fish hook would impact this suction feeding process.

“The suction feeding system is somewhat similar to how we drink liquid through a straw,” said Tim Higham, a member of the research team. “If you poke a hole in the side of your straw it’s not going to work properly.”

20 shiner perch caught near the Bamfield Marine Sciences Centre in Canada, ten caught with a net and ten with a hook, were brought to a marine station where the researchers set up high-speed cameras to record the fish feeding.

The fish were split into two groups depending on how they were caught and the researchers compared the feeding performance between the two groups.

Even though all the fish wanted to feed, the ones that had been caught with a hook were not able to feed as efficiently as the fish caught with a net.

“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 Higham.“This was the case even though we used barbless hooks, which are less damaging than barbed hooks.”

After modeling the fluid dynamics in the suction feeding system, the researchers were able to show how the hole injury left by a hook disrupts suction feeding, but there are still unaccounted factors that need to be understood.

“Although we don’t yet know how/if this reduction in feeding performance would affect fitness and survivability in nature, we can say that fishing-induced injuries impact the fish’s ability to feed while the mouth is healing,” said Higham. “This study emphasizes that catch-and-release is not as simple as removing the hook and all being well, but rather is a complex process that should be studied in more detail.”

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By Kay Vandette, Earth.com Staff Writer