In today’s Academic Minute, Dr. James Hanson of Seton Hall University explains efforts to reduce unwanted encounters between humans and sharks by developing an effective repellent.
James Hanson is a professor of chemistry at Seton Hall University where his research interests include organic chemistry and polymer/materials science. His research group is focused on creating materials for marine applications, including repellents for sharks and dolphins, sea lamprey control agents, and anti-fouling agents. He earned his Ph.D. at the California Institute of Technology.
Dr. James Hanson – Shark Repellent
According to old fisherman’s lore, if you hung a dead shark from your boat, live sharks would leave you alone – they wouldn’t steal your bait, they wouldn’t eat your catch before you reeled it in. To test this, my colleague Eric Stroud took shark discards from fishermen, aged them, and tested the resulting stinky stuff against sharks in real situations – and when done right, it worked! The sharks smell it as a chemical signal – a semiochemical – that signals danger, and they leave the area – even if there is food to eat!
But what exactly was the stuff that signals danger to sharks? We are working together on a chemical analysis to determine what chemical compound is the signal. We analyzed the semiochemical mixture by 2D gas chromatography with mass spectroscopy, and there are thousands of compounds in it. The next step was to separate them – acids from bases, high boiling points from low boiling points, and so forth – to make the haystack a little smaller: and we are getting close! We don’t know exactly what the active chemical is, but we know more than we did a few years ago.
We are also developing methods using polymers for the release of the semiochemical – so we can give sharks the signal to stay away from fishing boats, from swimming areas, and so on. This isn’t just to protect the swimmers – but to protect the sharks! While there may be 20 people killed by sharks each year – and that is too many – there are hundreds or thousands of sharks killed unintentionally by fisherman every day! They are fishing for tuna or swordfish and catch sharks by accident – so they just throw them out. But if we kill off most of the sharks, the ecosystem is a mess! So the most useful thing to come out of this project will not be protecting people directly, but protecting people by protecting the health of the oceans – by protecting sharks!