Wednesday, February 8, 2023

Self Releasing Hooks Good for Fish

Releasing fish can help conserve their populations, but the process of capturing and handling fish can result in injuries or death. These discard effects present a major conservation issue in recreational fisheries—for both catch-and-release fishing as well as highly regulated consumption fishing. Even if the percentage of injuries and mortalities are relatively small, fisheries where large numbers of fish are released can have cumulatively discard effects that impact the population.

Fishing practices and gears that minimize hook injury, handling, and air exposure can considerably improve the fitness and chances for survival in released fish. In particular, efficient dehooking substantially reduces the physiological stress in fish that typically occurs during the landing and release process.

Earlier field trials with bonefish on Palmyra Atoll conducted by one of the study’s co-authors found fish would “spit out” bite-shortened hooks once they were reeled in toward the angler and the angler gave slack in the fishing line. The idea appeared promising and prompted the researchers at the UF/IFAS Nature Coast Biological Station to begin more rigorous testing. To our knowledge, these are the first assessments of hooks designed to self-release from fish and fully eliminate fish handling.

Research objective: We tested whether hooks modified to be barbless or bite-shortened (Fig. 1) to see if they could allow anglers to reel-in a popular coastal sport fish, Spotted Seatrout (Cynoscion nebulosus), and then allow the fish to be released in the water and without direct handling. Seventy-five fish were caught-and-released with each hook type.

The unmodified jighead “standard” hook had a 15-mm bite distance and backward facing barb. The barb on a standard hook was removed to make the “barbless” modified hook. “Bite-shortened” modified hooks were made by reducing the bite length of a barbless hook to 10-mm, which also removed the barb.

·Short video demonstrating how to modify a standard hook to a bite-shortened hook

Findings: We found promising results for a potential self-releasing fishhook. The bite-shortened modified hook enabled anglers to land 91% of hooked Spotted Seatrout and then release 87% of those fish without direct handling. In comparison, the self-release success rates were 20% using barbless hooks and 47% using standard, unmodified hooks. We also found that smaller fish were able to be released without handling at higher rates. These smaller fish are often protected in length-regulated fisheries and reducing their discard mortality can help conserve fishery resources.

·Short video showing the bite-shortened hook releasing from the fish in slow motion

Implications: A proven and effective self-releasing hook gear may have broad conservation and management applications in recreational fisheries as a means to minimize or eliminate injuries and mortalities in catch-and-release fishing. A foreseeable use-case for self-releasing hooks could be to allow restricted fishing in sensitive fishing areas, for example, in no-take aquatic protected areas or areas experiencing unsustainable fishing pressure. Further research with different lures, species, and anglers appears warranted.