WASHINGTON (CN) – Longline fishing trawlers in the Gulf of Mexico must use weaker hooks to help bluefin tuna escape being caught incidentally, according to new rules issued by the National Marine Fishery Service.
The rules, effective May 5, require commercial trawlers in the gulf to use thin gauge wires (less than 3.65 mm in diameter), which are likely to bend and straighten under the weight of the tuna.
Experimental fishing using the weaker tensile strength hook resulted in a nearly 57 percent reduction in by-catch of bluefin tuna, according to the agency.
The agency predicts a likely reduction in incidental by-catch from 285 fish per year to approximately 124 fish, if the experimental results hold true in practical application.
Not only are larger fish more likely to escape from the weaker hooks before being hauled aboard, but the hooks cause less damage to fish caught and released, making survival more likely than if they were caught using existing hooks.
The weaker hooks used in the study did allow some, larger target fish – such as the yellowfin tuna – to escape. The agency argues that this may, over time, increase the size of target fish as smaller adults are removed from the breeding population.
The same may be true for the bluefin tuna, whose individual body mass and overall breeding population have been in sharp decline since 1980.