Monday, September 29, 2014

Is Trophy Fishing Driving Fish Extinction?

Fishermen land a large tiger shark
A new paper in Marine Policy finds that 85 species assessed as threatened by the International Union for the Conservation of Nature (IUCN) Red List of Endangered Species are also targeted by recreational fishermen hoping to break International Game Fishing Association records.

The researchers suggest that if the IGFA were to stop issuing records that "implicitly require killing the fish for IUCN Red List Threatened species, it would immediately reduce fishing pressure on the largest individuals of species of conservation concern while still allowing anglers to target more than 93% of species that records have been issued for."

I caught up with lead scientist (and Twitter superstar) David Shiffman with the RJ Dunlap Marine Conservation Program at the University of Miami and asked him a few follow up questions regarding his study.

@saipanblogger: Thanks for taking the time to answer a few questions, David. I admit it was hard coming up with questions because you do such a good job filling in any gaps in your study with a Q&A on your blog.

So here we go. Many people think of you as primarily a shark scientist, but this study is about all species listed on the IGFA records list. How many of these species are sharks, and how many of those are threatened? And what’s the difference between a shark that is assessed as threatened, near threatened, or least concern?

@whysharksmatter: An IUCN Red List assessment is a scientific evaluation of the conservation status of a species. There are formal definitions, but basically Least Concern means that populations are healthy, Near Threatened means we should pay attention, and Threatened (which includes Vulnerable, Endangered and Critically Endangered) means that the species is in trouble and may face extinction if trends continue.

Recreational fishing can be a threat to fish populations, including sharks. Trophy fishing targets the largest individuals in a population, which are often the females capable of having the most (and the healthiest) babies. We identified 85 IUCN Red List Threatened species that are targeted by trophy fishing, including more than a dozen species of sharks and their relatives

@saipanblogger: Austin Gallagher previously authored a study that showed high mortality rates for certain species of sharks caught in recreational fisheries. Based on the conservation status of shark species and the results of Austin’s paper, what recommendations would you make for managing recreational fishing of sharks?

@whysharksmatter: Many anglers practice catch and release when fishing for sharks, but if the catch part is stressful enough, the fish will die even after release. It's critical to minimize fight time, particularly for especially sensitive (and threatened ) sharks like hammerheads.

@saipanblogger: IGFA has already responded to your study saying that they are not going to change their categories. Other than getting rid of the categories, are there measurements IGFA could use other than weight to determine world records?

@whysharksmatter: If the IGFA was to respond to the concerns of many marine biologists and conservationists that we raised in our paper by no longer issuing weight-based all-tackle world records (which implicitly require killing the fish) for IUCN red list threatened species, it would reduce fishing pressure on the largest individuals of these species. As we said in our paper, few policy changes can do so much for so many species for so little cost. The IGFA could switch to length-based records, which can be done using catch and release.
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