Shark depredation: a frustrating experience for fishermen in the Atlantic

Saltwater fishing boat with poles in the Gulf of Mexico near Alabama © NOAA Fisheries

Shark depredation is the partial or complete removal of a hooked fish by a shark directly from an angler's line before the line can be retrieved. It is a growing concern for recreational anglers.

NOAA Fisheries is taking steps to better understand the frequency of depredation events and the circumstances around these interactions.

Research shows several possible reasons for an increase in shark depredation.

• More sharks: Populations of some shark species have recovered from overfishing thanks to NOAA Fisheries' conservation efforts under the Magnuson-Stevens Act.
• More anglers: Increasing numbers of anglers releasing more fish—possibly injured or dead—which can attract sharks.
• Learned behavior: Some evidence suggests sharks can learn from previous interactions and begin to associate the sounds of fishing boats with easy meals.

It is important to consider that sharks are not the only animals capable of depredation. Dolphins, seals, groupers, and other large fish are all known to feed on anglers' catch. While sharks are easy to blame, they are not always the culprit.

Diving deeper with research

We are funding research into shark depredation in recreational fisheries. A recent study by researchers at Florida Atlantic University and Mississippi State University set out to:

• Assess the extent of shark depredation in the southeastern United States, with a particular focus on Florida.
• Identify the major depredating species and fisheries involved.
• Understand how depredation shapes angler attitudes towards shark conservation and management.

Using social media data, angler surveys, and DNA analysis, researchers determined that there were distinct regional and seasonal differences in depredation probability. The highest probability occurred during the spring and summer seasons. There was a consistently high probability of depredation in the southeast and Florida Keys across all seasons.

Survey results also showed that angler perceptions of depredation were consistent with findings from other studies. Most respondents felt that depredation levels have stayed the same or increased in the past 5 years, and anglers who experienced depredation were less willing to support shark conservation efforts.

Most commonly depredated species

Overall, the study revealed the most commonly reported depredated species in Florida were:

• Greater amberjack
• Mutton snapper
• King mackerel
• Gag grouper
• Sailfish

Species most frequently preying on catch

Using DNA swabs of shark-damaged fish collected by fishing charters, researchers identified sandbar sharks and bull sharks as the species most frequently preying on catch. This was consistent with what anglers in the Southeast reported in surveys and online.

Addressing depredation

Shark interactions with fisheries are complex and challenging. NOAA Fisheries is committed to better understanding and finding ways to minimize interactions. To this end, we're:

• Conducting stock assessments on sandbar and bull sharks, the two species identified as the primary depredating species, in the coming years
• Supporting research aimed at better understanding how anglers can better avoid depredation, including recently funded studies assessing shark deterrent technologies
• Identifying effective ways to systematically monitor depredation, such as collecting data on these events as part of regular dockside surveys of anglers or through the use of mobile reporting apps