Shark on the Line!

Florida Sea Grant Stock Photo

What actually happens to a shark when it is hooked, fought and released?

  • Hook is set into the shark, ideally in jaw, but can also get hooked in mouth, gills, stomach, or foul hooked in body, fins, or tail.
  • Shark fights against fishing line, causing changes in their physiology. This is known as the "fight or flight" stress response.
  • Certain species will fight harder than others.
  • Shark is eventually brought to the side of the boat, dehooked and released.

    Stress on sharks

    Fighting the shark on the line causes the greatest distress on the animal, which can result in increases of stress hormones and changes in blood chemistry.

    These changes can cause the build up of metabolic products and acids that can cause death if the shark does not recover from the stress event or fights itself to extreme exhaustion. In some cases, sharks can recover from the fishing stress.

    A recent study led by researchers at the University of Miami analyzed how five different species of sharks in Florida responded to the stressors of catch and release fishing.

    Watch this short video for an explanation of what the researchers found!

    University of Miami Researchers Study Shark Stress

    The researchers looked at how blood physiology and reflexes changed in blacktip, bull, great hammerhead, lemon and tiger sharks. The animals were caught using a variety of fight times, ranging from two minutes to 180 minutes.

    The team also placed satellite tags on bull, hammerhead, and tiger sharks to estimate their survival rates after release. The researchers documented a wide range of sensitivity to fishing between species.

    Tiger and lemon sharks were shown to recover from catch-and-release fishing, while other sharks like hammerheads and blacktips were much more sensitive.

    The study found that nearly 50 percent of hammerheads actually suffered mortality after they were released, regardless of the length of the fight.

    Even though a shark may swim away after it is released, it does not mean that it will necessarily survive the encounter. This research was supported by Florida Sea Grant and it can be found at: University of Miami Researchers Study Shark Stress

    Explore the Species Focus page to learn more about the results of the study and which species are more susceptible to stress.

    In review

    Photo by Austin Gallagher

    Research shows that different species of sharks seem to have their own personality in terms of how they respond to catch and release. Some species are great candidates for catch-and-release fishing, while others are clearly not. For those species which fall into the sensitive category, anglers are encouraged to be especially responsible and act in accordance with the recent scientific findings and the best handling practices available.

    Additional resources