For Deep-Hooked Bogue, De-Hookers Did No Better Than Cutting the Line

Loss of orientation after release was a strong warning sign of later death, while preventing deep hooking offered the best survival prospects.

Editorial illustration — not from the study.

Researchers examined post-release survival and impaired reflexes in bogue, a fish commonly caught in Mediterranean and Atlantic temperate fisheries. Overall, 20.4% of the fish died after release, with most deaths associated with deep-hooking events.

When fish were deeply hooked, mortality did not differ significantly between those treated with a de-hooker and those released after the line was cut. Loss of orientation was especially common in deeply hooked fish and strongly predicted mortality; fish showing both bleeding and disorientation consistently died.

What happened after release

Overall post-release mortality was 20.4% (95% confidence interval: 13.5% to 29.4%), and it was largely associated with deep hooking. Among fish with shallow hook locations, manually removing the hook was associated with 2.5% mortality (95% confidence interval: 0.1% to 14.7%). In deep-hooking cases, mortality was 29.4% after line-cutting (95% confidence interval: 15.7% to 47.7%) and 32.4% after use of a de-hooker (95% confidence interval: 18% to 50.6%). The difference between line-cutting and de-hooker use was not statistically significant.

Loss of orientation was a strong predictor of post-release mortality and was most frequent among deeply hooked fish. Bleeding was also associated with mortality. The combination of bleeding and disorientation consistently resulted in death. Neither reflex impairment nor bleeding differed significantly between the de-hooker and line-cutting groups, suggesting that de-hookers did not reduce the physiological damage caused by deep hooking.

Why deep hooking matters

The findings point to preventing deep hooking as the most effective way to reduce post-release mortality in bogue. Once a fish is deeply hooked, using a de-hooker produced survival outcomes similar to cutting the line, rather than improving them. Checking whether a released fish can maintain its orientation may also help identify individuals at especially high risk of dying.

Evidence and caveats

This was a research study comparing post-release mortality, reflex impairment and bleeding across hook locations and release treatments. The abstract reports mortality estimates and confidence intervals, but it does not provide the sample size, follow-up duration, detailed fishing conditions or the full study design. The findings directly concern bogue and may not apply in the same way to other fish species or fishing situations.

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