Damage caused by the hook as a result of a kill hinders the feeding performance of the fish

Fishermen do not plan to dine at home when they practice catch and release fishing, but they may not be the only ones to miss a meal.

In a study published today in The journal of experimental biology, a research team led by UC Riverside has shown that mouth injuries caused by withdrawal of hooks after release fishing impede the ability of fish to capture prey. The findings add to an increasing number of publications raising questions about the practice of resettlement and release fishing, which is considered by many to be a means of conserving fish species at risk.

Tim Higham, associate professor in the Department of Evolution, Ecology and Biology of UCR Bodies, is studying the biomechanics and hydrodynamics of suction feeding, which is the Consumption mode of many species of sport fishing fish, including bass, salmon and trout.

During suction feeding, fish quickly develop their mouths to suck their prey. This generates a negative pressure inside the mouth relative to the surrounding water. The suction feeding depends on the resulting pressure gradient to attract prey into the mouth. Higham and his colleagues were wondering if an extra hole, caused by the removal of the hook, could disrupt the system.

"The suction feeding system is a bit similar to the way we drink liquid with a straw," Higham said. "If you make a hole in the side of your straw, it will not work properly."

To study the effects of releasing on food performance, Higham and his colleagues studied 20 collared perch caught near the Bamfield Marine Science Center in Canada, including 10 at the line and 10 at the net. After being caught, the fish were immediately transported to the marine station, where researchers used high-speed cameras to quantify the feeding performance of fish from both groups. The fish suffered minimal stress, which was returned to the wild at the end of the experiment.

As described in the study, although all fish have the same motivation to feed, the feeding performance of fish with hook-related mouth sores has been significantly reduced compared to net caught fish.

"As we predicted, fish with mouth sores exhibited a reduction in speed at which they were able to attract prey into their mouths," Higham said. "That was the case even though we used barbless hooks, which are less damaging than barbed hooks."

By modeling fluid dynamics in the suction feeding system, the researchers confirmed that performance was decreasing due to the hole caused by the hook, but they also found that the only mouth injury did not occur. could not fully explain the reduction in feed performance, suggesting the release could affect the ability of a fish to feed in other ways.

Higham said that further studies are needed to determine the long-term effects of reduced dietary performance.

"Although we do not yet know whether this reduction in feeding performance would affect fitness and survival in nature, we can say that fishing-induced injuries affect the fish's ability to feed while its mouth heals. ", did he declare. "This study points out that catching up and releasing is not as simple as removing the hook and that everything is fine, but rather that it is a complex process that should to be studied in more detail. "

The document entitled "Angling-Induced Injuries has a Negative Impact on Feeding Performance by Suction and Hydrodynamics of the Marine Wool Perch, Cymatogaster aggregata".

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More information:
Melissa Thompson et al., Injuries induced by angling have a negative impact on the sucking performance and hydrodynamics of the brown perch, Cymatogaster aggregata, The journal of experimental biology (2018). DOI: 10.1242 / jeb.180935