The sportfishing record for the critically endangered goliath grouper (above) is 308.4 kilograms, set in 1961.

LASZLO ILYES/Wikimedia

The sportfishing record for the critically endangered goliath grouper (above) is 308.4 kilograms, set in 1961.

Scientists want end to traditional trophy fishing of threatened species

Allie is a freelance science journalist in Washington, D.C.

An international angling group should stop awarding weight-based world records for fish species threatened with extinction, researchers argue in a new study. The awards encourage the killing of the heaviest, most fecund fish, the scientists say, and should be replaced by conservation-friendlier records based on length.

Since 1939, the International Game Fish Association (IGFA) of Dania Beach, Florida, has been a leading record-keeper for recreational anglers, certifying who has caught the biggest fish. Today, it maintains records for some 1200 species.

In their study, published online before print in Marine Policy, the researchers found that 85 of those species are listed as either vulnerable, endangered, or critically endangered by the International Union for Conservation of Nature (IUCN) Red List. That’s a concern, the authors say, because although commercial fishers are sometimes barred from killing endangered species, recreational anglers often can. The researchers are particularly worried about the impact of trophy fishing, because removing the largest individuals can have a disproportionate impact on a population.

The most common method of certifying the size of landed fish is based on mass. But weighing large fish typically requires anglers to transport them to an official land-based weigh station—a method that makes it unlikely that the fish will survive. In many cases, this means the loss of egg-bearing females, because the females are larger than males in many species. So by killing big fish, the authors note, trophy anglers often remove individuals that are capable of producing the most high-quality larvae and helping depleted populations recover.

Shifting to length-based records could reduce such mortality, says the research team, led by researchers at the University of Miami’s Abess Center for Ecosystem Science and Policy. Anglers could use cameras or smart phones to validate catches and release record fish where possible.

“If the IGFA stopped issuing records that implicitly require killing the fish for IUCN Red List Threatened species, it would immediately reduce fishing pressure on the largest individuals,” they write. “So long as there are incentives to catch the largest, oldest, most fecund and fittest individuals within a population, recreational fishing pressure will continue to target these fish and likely exacerbate population declines.”

IGFA already uses length-based records to verify some “catch-and-release” records. The scientists recommend that the IGFA now declare that weight-based world records will no longer be issued for species on the IUCN’s Red List.

The proposed change would affect just 7% of the species on IGFA’s list and have only a small impact on anglers, according to the researchers. But “few policy changes in the world can do so much for so many species for so little cost.”

David Shiffman, the study’s lead author and a marine biologist studying shark biology and conservation at the University of Miami, says the analysis was inspired by recent hearings concerning a proposed ban on killing scalloped and great hammerhead sharks in Florida waters—two species listed as endangered on the IUCN Red List. “Several anglers said they were opposed to protecting these species, one of which is so depleted that it just became the first species of shark protected by the U.S. Endangered Species Act, because it would stop them from going for IGFA world records,” he says.

As ScienceInsider went to press, IGFA had not responded to a request for comment.

Posted in Biology, Plants & Animals, Policy