TODAY | October 30, 2013
>>> first there was shark week and then sharknado. sharkmania is everywhere. people can't get enough including this guy, willie.
>> it's the jaws imagine. the imagine of sharks that researchers are trying to change about the endangered animals. i joined one team off of florida and dove right into the action.
>> reporter: off the tip of the florida keys , neil and his team from the university of miami 's marine conservation program spend their weekend searching for sharks .
>> you'll see. it's a lot of comotion but everybody gets in and does their job and gets out and puts the sharks back in.
>> everything they catch is released safely but only after the researchers have taken valuable information and tagged the biggest sharks with a special satellite device that tracks their feeding and migration habits. the team hopes the prize data can help illuminate the world of sharks . but before we gather data, we have to catch something.
>> you want big fish , you need big bait.
>> reporter: oh.
>> we dropped 30 lines and then pulled them up one by one hoping there's something alive at the other end. we strikeout on the first two tries.
>> there's no shark on there now.
>> reporter: but then, a small black tipped shark is on the hook. once the shark is up on the boat, we pump saltwater into his mouth to keep oxygen flowing and i take measurements. then we clip a tiny part of the finn and take tissue samples for analysis. then, in a matter of minutes the shark goes back into the water.
>> good job.
>> he got off in a hurry.
>> reporter: sharks are increasingly threatened around the world by human activity. often hunted only for their finns.
>> when most people think about extingt animals they don't jump to sharks . there's the idea that they're the great predator at the top of the food chain and they'll be okay forever. what's the reality?
>> some of the species declined 80% over the last 10 years. a lot of the animal versus been threatened and some of them endangered with extinction.
>> guys, we have a strong nurse shark .
>> reporter: then we get on a roll.
>> caught three sharks already. the feeling on the boat is the big one is still out there.
>> we pulled up a hammerhead. we decided too small and too fragile to tag and do the full battery of tests. we look how long it was and sex and send it on its way.
>> reporter: researchers hope with all of this data they can understand and protect the lives of sharks .
>> so three nurse sharks and three black tips. a hammerhead which was rare. it's only my first time doing this but it feels like a good day.
>> that's a great day. three different species including an animal of conservation concern. really good data points . not more you can ask for.
>> that was a fun day. it looks a little rough but the team there follows a really strict set of safety precaution with the hooks they use to get the sharks and they take the samples out of part of the body where there's no nerve endings so it doesn't hurt the shark .
>> how do they find out the sex of the shark ?
>> we left that up to the scientists natalie. they have their methods. what's your take away? we're trying to save the sharks here and she wants to know how you tell a male from a female. the scientists have methods.
>> we're back in a moment. first this is "today" on