It’s estimated that tens of millions of sharks die from incidentally being caught in fishing gear each year—more commonly known as bycatch—from longlines, trawls, and gillnets. Commercial pelagic longlines are particularly dangerous, dangling thousands of baited hooks into the water for extended periods of time, typically intending to catch swordfish, mackerel, and tuna. But these baited hooks make a tasty and easy meal for sharks and other marine species, so longlines often incidentally catch sharks—and sometimes in quantities even larger than their intended catch.
Fortunately, a new invention may help reverse sharks’ fate when it comes to bycatch. A new polymer called SuperPolyShark has a scent so strong that it deters sharks from approaching the baited hooks, while still attracting the targeted species like swordfish. Created by Shark Defense Technologies, a New Jersey-based team that specializes in developing shark bycatch reduction tools, the polymer can be inserted into baited hooks and keeps its scent for several hours underwater.
The researchers tested various scenarios of SuperPolyShark, using various molecular weights across different soak-times. Overall, the scented hooks resulted in a 39 percent less bycatch across all trials, though some combinations resulted in up to a 71 percent reduction. The repellent’s effectiveness was limited to twelve hours underwater, according to a study, so the researchers call for more research on the material.
The National Oceanic and Atmospheric Administration (NOAA) awarded Shark Defense Technologies and Key West Community College a grant in 2012 to research this technology as part of their Bycatch Reduction Engineering Program, according to Asbury Park Press. The program focuses on developing technologies and changing fishing practices that work to both reduce bycatch and minimize bycatch injury and mortality.
Bycatch is said to be one of the largest contributors to shark declines around the world, according to Pew Charitable Trusts. Their life history characteristics make them particularly vulnerable to overfishing, since many species are slow to grow, mature late in life, and only give birth to a few young. Once sharks get caught on longlines, very few survive—which makes it important for innovative ideas to receive funding and support so that to minimize the impacts of human activities on sensitive marine creatures.
Oceana actively campaigns to reduce bycatch for sharks—especially the dusky shark, which has declined by as much as 85 percent over the past 40 years—and other protected species like sea turtles and whales. Earlier this year, Oceana released a report, “Wasted Catch,” that outlined nine of the worst U.S. fisheries for bycatch, like the southeast snapper-grouper longline fishery ad California set gillnet fishery. Oceana has called on government officials and fishery managers to reduce bycatch, and urges them to adopt the Oceana approach to limit bycatch: count the entire catch, cap the catch with science-based limits, and control bycatch through advanced monitoring and better gear types. Click here to learn more.