Teeth of the Tiger

Although I've already posted about tiger sharks, it was a little tough to see because all the pictures were taken at night.  Not so anymore.

This handsome fellow, measuring in at 302 centimeters (about 9 feet 6 inches), was caught on our deep line that we set last week.  A deep line is essentially the same as a longline (discussed in the previous post about tigers) except instead of being stretched a long ways horizontally in shallow water, it is stretched vertically in much deeper water, about 750-800 feet.  We made numerous attempts to get big tiger sharks for a big game fisherman/conservationist named Guy Harvey.  He was at the lab along with a few big-name shark scientists shooting the end of a documentary on tiger sharks.  For those that don't know, Guy Harvey is HUGE in the southeastern U.S.  The people from Florida here acted like they were 14 year old girls meeting JT or something.

 That's Guy Harvey with the camera.  He shoots most of his footage himself and as you can see he gets right on in there.  For a born-rich adventure seeker, he's actually a really nice guy and completely devoted to marine conservation, so it was pretty cool to meet him and hang out with him.  Also didn't hurt that he has a resort and restaurant on the north island, which he brought us to and treated us to a fantastic dinner.

There was also a scientific purpose to catching the shark.  In this picture you see two of the scientists on Guy Harvey's team fixing a satellite tag to the shark's dorsal fin.  The tag will record data on sunlight, water depth, and a few other factors and using all that, the scientists can figure out where the shark swims.  After about 6 months, the tag pops off and floats to the surface and broadcasts the data.

I don't actually have anything to say here, this is just an awesome picture.  The release got a little hairy; instead of swimming down and away, which is what normally happens in these situations, this guy decided to cruise around at the surface for a while, where all the people happened to be.  Guy Harvey's camera man got a phenomenal shot when the shark swam within inches of the camera and opened its mouth real wide.  It swung around after that and came right at me and another volunteer.  I have a video of the whole thing, about 3 and a half minutes long, but it won't load into the post for some reason.  It's pretty wild, so if you're interested shoot me an email and I'll try to send it to you.

Incidentally, while in the process of writing this post, which took over a week, we caught another tiger on a deep line we set for the students from Eckerd College.  She was a big momma...

She clocked in at 336 centimeters (a shade over 11 feet), but she actually should have been about 20 centimeters larger; the end of the tail fin had been bitten off, most likely during mating.

As you can see, this shark is almost as big as the boat she is tied to.  If you look at the picture of the other shark from last week, the difference of only about 30 centimeters makes a tremendous difference in the size of the shark.  Not only is it obviously longer, the difference in width is enormous.  The mouth of this one seemed to be double the size of the smaller male.  It's amazing how much of a difference a few centimeters makes.

There is also a picture floating around of me basically giving her a hug, but I haven't managed to get my hands on it yet, so it'll have to wait until next time.

Grab the Bull by the Horns

Ladies and gentlemen, the bull shark.

As much as I've tried to learn you something about how sharks are not nearly as bad as they are portrayed by people, the bull shark does actually merit extreme caution.  Growing up to over 11 feet long, bull sharks are set apart from other sharks in that they have very volatile personalities.  Whereas most other shark species have, for the most part, predictable behaviors in certain situations, the bull shark can go from a fantastically exciting thing to see to truly frightening in a heartbeat.  Bull sharks rank in the top 3 when it comes to number of fatal attacks, just behind great whites and tigers.  However, there are some reports of shark attacks not attributed to bulls when it is likely that a bull shark was responsible. 

One very special aspect about the bull shark is that it can not only survive, but thrive in fresh water.  Bull sharks are known to swim hundreds of miles up rivers and there is even a small population of permanent residents in the Brisbane River in Brisbane, Australia.  While fascinating, this also contributes to the high numbers of attacks on humans.

Generally, I will tell you that if you see a shark in the water, don't panic, just relax, stay aware and enjoy.  The bull shark is a bit different.  If you come across one of these guys in the water, I STRONGLY recommend getting out.  Fast...

All that being said, on to the cool stuff.  This is us grabbing onto a nice 232 centimeter (about 7 feet 7 inches) male with a student from Eckerd College standing about 5 feet from his face. We caught him just off the docks on the north island using just a hook attached to a rope with a large, glowing orange ball on top so we could see where the shark went after we hooked it.  After we pulled it up to the boat, we did a quick work-up, took some DNA samples and put a Casey-tag in.  A Casey tag is a small tag attached at the base of the dorsal fin with an identification number on it.  If the shark is caught again, the tag can be removed and there are instructions on the back directing people to contact the National Marine Fisheries Service.  This way, if the shark is caught again, and the people who caught it feel like it, we can get a little data on where the sharks go.

I was the one to put the Casey tag on this guy, and if I do say so myself, it was a beautiful tag.  The way to tag a shark is to take a device, actually looks like a rolling pin with a barb on the end with the tag in the barb, and slam the barb into the shark.  It sounds brutal, but the sharks can't feel it.  Shark skin is very thick, so you really have to hit it hard and a lot of times it takes more than one shot.  Unless you're me of course; one shot, straight in, in front of a crowd of 20 onlookers waiting for me to screw it up.  But obviously I'm calm cool and collect under pressure, and as another volunteer commented afterward, I hit it "like a boss."  Thunderous applause followed and a well-deserved bow.

The whole tagging and work-up process only takes about 5 minutes, even with all the explanations for the benefit of the students in the course.  It is very low-stress for the shark and we try to get them off the boat as fast as possible.  As soon as the hooks and ropes were off, this guy took off into the the sunset, no worse for wear.  Today is your lucky day too, because there will be not one but TWO posts!  Stay tuned...

Tracking

As promised, though maybe delayed, this is the first installment of the "techincal" aspects of the shark lab.  Actually, this post will be about what I do a majority of the time that I'm here because the Phd. candidate is doing her project on the movements of juvenile lemon sharks in relation to mangrove forests.  As mentioned before, the North Sound of Bimini has been stripped of a large fraction of its mangroves to make room for the Bimini Bay resort.  Not to give anything away, but there is a sizeable difference in the movement patterns before and after construction.

Anyways, the way we monitor the movements of sharks is fairly simple.  There are currently 10 baby lemon sharks swimming around with acoustic transmitters implanted in their body cavities.  The transmitter emits a high-frequency signal, which the sharks can't hear or feel, which is then picked up by our hydrophones and made audible to us by a receiver.  What's a hydrophone you ask?

This is a hydrophone.  We sit on the front of our skiffs...

(these are our skiffs) and stick the hydrophone in the water and listen for a signal from a shark that carries a transmitter.  Basically when the hydrophone is pointed at a shark that has a transmitter, it picks up the signal and is attached to a receiver which is attached to our heads with a pair of headphones.  The closer you are to the shark and the more on-target you are with the hydrophone, the louder the signal.  The signal is a series of numbered beeps unique to each shark.  For example, one transmitter pulses out a series of 4 beeps, then a short silence, then 7 beeps, then another silence, then 8 beeps followed by a long silence.  The process then repeats, resulting in this shark being ID'd as 478.  So tracking looks a little something like this...

As you can see, the shark we are tracking in this picture (that little sliver of dark dead center) is extremely close to the boat and my friend Mike here is giving the "put the boat in neutral, you're gonna run over the shark" signal (clenched fist).  The receivers have a range of about 60 meters (about 200 feet for those metrically impaired), so most of the time we can't actually see the shark and just have to rely on our ears.

Tracking crews consist of 3-4 people, a driver, a tracker and a person to record the data (if there is a 4th, there's a person on break).  Once a shark is identified, every 5 minutes the data person records the time, GPS coordinates, bearing and distance to the shark (in what direction and how far away it is in relation to the boat), sea floor composition, amount of cloud cover,  and salinity (how salty the water is).  Now, it isn't always easy like you see above, sometimes you track more than one shark at the same time and you have to distinguish between overlapping beeps of different pitches.

 (sharks are just right of the right shirt sleeve and more or less dead center just below the dark patch on top)
Also, sometimes the weather kind of sucks.

This is Michelle's sad rainy face.
And sometimes the weather really sucks and you forget your rain gear...

Winds gusting up to 55 knots (about 65 mph) out of the north (COLD) + torrential rains = never EVER forget to bring your rain gear, no matter how nice it is in the morning.  But for every crappy day of tracking, there's a lot more good days, and sometimes even a fantastic one.

Sitting on a boat for 8 hours in a tropical paradise with 2 or 3 good friends doing work that will help better our understanding of one of the coolest animals on the planet ending in a sunset like this...yeah, you kind of forget those bad tracking days.

Lemon Love

Right, so now that I've been here for almost 2 months, I feel like it's a little strange that I haven't done a post on the one shark I work with pretty much every day.  So without further ado, I bring you the lemon shark.

Lemon sharks are the reason the Bimini Biological Field Station exists.  The man who founded the lab, Dr. Samuel Gruber, has dedicated his life to understanding these sharks.  Right now, we have a Phd. student at the lab conducting her research on juvenile lemon sharks to see how they are affected by the destruction of nursery habitat on Bimini island. Almost everything we do is gathering data for her project.

(Note, the resort called Bimini Bay is kind of the bad guy in all this, but it isn't so simple. The project has brought a lot of jobs to the island but at the same time has destroyed valuable mangrove habitats that the lemon sharks and many other marine species use as a home.  That is what Kristine's project is all about.  What's worse is that the owners of the resort cleared off more land than they could afford to develop in an attempt to attract investors.  Basically they bulldozed about 2 square miles of mangrove forests for no reason other than to make it seem like they were making progress.  Boo them, but do it quietly because Bimini needs the jobs.  Anyways...)

So about the lemon shark...They can grow up to 13 feet long, but generally top out at about 10 feet.  The ones you see in these pictures are juveniles, no bigger than about 2-3 feet long.  That being said, these kids are STRONG.  The second day at the lab, we had a half-day class devoted to how to handle juvenile lemon sharks.  They are fast, strong, and can pack a mean bite if you don't respect them.  Lemon sharks are set apart from other sharks in a few ways.  First, they can pump water through their gills without swimming, allowing them to breathe without moving.  (If you recall, tiger sharks and nurse sharks also share this ability.)  Another defining characteristic is that the first and second dorsal fins (the ones on top, in case you forgot) are almost the same size.  In most sharks, the second dorsal is significantly smaller then the first.

The way to hold them is just behind the gills but in front of the first dorsal fin.  Lemons are extremely flexible, so if you try to hold them anywhere behind the first dorsal, they can whip around and grab on to you.

Here at the lab, we have a bunch of different tasks to perform involving baby lemon sharks; too many for just one post.  From here on out, I'm going to try to do a post a week describing the different things we do to study the sharks.  Originally I thought this would be too boring for most people, but nothing terribly awsome is happening so I want to put something up.  I'll start with tracking, and then move to pen trials, seining, and then eversions (you pull a sharks stomach out through its mouth to see what it has been eating...SO cool.)  I have pictures for tracking, but not enough for seining and eversions, hence the weekly posts and not daily.  That will bring us to the end of March when mini-PIT happens, and that's an entity unto itself.  So until tracking day next week, adieu.

A Tale of Two Tales: Part II

So we left off yesterday around 11 am.  We got back from the shark dive and the film crew went off to find some dolphins or some shit.  Everyone knows dolphins are just gay sharks, so we weren't all that interested.  The day before yesterday, two other volunteers and myself were tasked with chopping up bait for various activities.  Four hours of that was enough to make a pair of shorts permanent bait-cutting shorts and force me to make some adjustments to the facial hair.  Some bait splattered up onto the mustache and it was all I could smell so I decided to remove some.  The end result looks something like if Wolverene were 100% Irish.  Anyways, the three of us were rewarded by going out to bait for hammerheads to try to get some good shots for the film crew.  It is still very early in the hammerhead season so we were not too optimistic.  After a few hours, we finally had a visitor.

Lindsay was in the water scraping (holding a large piece of bait and consistently scraping down the fish to create a steady scent trail that the sharks can follow back to the boat) when she looked up and said, "There's a shark down there."  We get excited and start putting on our fins and such to jump in when she comes back up and tells us it's just a nurse shark.  It took the wind out of our sails a bit because nurse sharks are pretty boring.  They can grow up to 14 feet long and are essentially harmless to people.  They are almost always found just resting on the sea floor; they are one of a handful of sharks that can pump water through their gills without swimming.  Not so exciting.  But as Derek and I are about to get out of the water, Lindsay looks up and whispers, "There's a hammerhead down there."  I had a much more enthusiastic reaction, after I looked down and saw this...

I looked up and yelled, "HOLY FUCK, there's a hammerhead down there!!"

This is the second post about hammerheads but I realize that I didn't really give the little briefing on the species like I have with the other ones.  There are a few types of hammerheads, the one shown here and in the one in the earlier post are both Great hammerheads.  These sharks are just magnificent, capable of growing up to 20 feet long and sporting one of the most unique and recognizable body shapes in the animal kingdom.  Not only the shape of the head, but also the ridiculously tall dorsal fin.  It is for this reason that Great hammerheads are listed as endangered.  In many parts of the world, most notably Asia, sharks are killed by the tens of millions every year just for their fins.  Having such large fins makes Great hammerheads ideal targets for shark finning.

Fishermen land the sharks, cut off all their fins, and then throw the body back into the water.  Usually the shark is still alive at this point and either bleeds to death or suffocates because it cannot swim to keep water flowing through its gills.  While it is estimated that populations of Great hammerheads have dropped 50% in the Western Atlantic, 73% in the Indian Ocean, and over 80% in Western Africa, there have been only 37 recorded attacks on humans by Great hammerheads, only 1 of which was fatal.  Once again, that's 1 recorded fatality since the creation of the International Shark Attack File during World War II (the number of attacks and fatalities you see in this blog come from this source).

But enough of that depressing stuff, back to the awesome day yesterday.  We called in the film crew so they could try to get some shots of our new friend, who was about 10 feet long.  But before they could get there, he grabbed one of the baits and started "hammering the nail", thrashing his head back and forth until he ripped through the line and swam off with his prize.  We thought that was the end of it, reveling in the fact that we got to witness a very rare shark.  We were very, very wrong.

At this point, it was around 5:30, starting to get dark, when out of that deep, deep blue came first the original hammerhead, then a second, slightly smaller one, and finally the nurse shark from the beginning bringing up the rear.  We  were anchored in about 20 feet of water, so these guys came in nice and close to smile for our respective cameras.  When we set out from the dock, Jim, the lab manager, said that best case scenario was that we would get a hammerhead to stick around for maybe 15 minutes.  We were in the water with these two for 45 minutes, until it was almost too dark to see anymore.  It capped a day that I will remember for the rest of my life as one of the best.  I'll leave you with some of my favorite pictures.  If you would like to see more, I have about 50 as well as a couple of videos, just let me know and I'll shoot them to you.  There is a short clip at the end of this post, but I have a 3-minute gem of all 3 sharks.  If you would like to see it, let me know and I will try to upload it to Youtube.  Stay sharky kids.

A Tale of Two Tales: Part I

So today was sort of epic.  I got my underwater camera 2 days ago and it immediately paid dividends.  The past few days there has been a French film crew at the lab, so today we tried to do all the fun stuff so we could get them some good footage.  Part one of this segment is dedicated to the morning shark dive, which the new volunteers did 2 weeks ago and were able to do again because the film crew wanted us in the shot.  This was the result.

This shot has all Caribbean reef sharks, but there were also some black-nosed sharks around as well.  Caribbean reef sharks can get up to 10 feet long, but these guys ranged from 5-7 feet.  The first time out, someone counted 12 sharks on the dive, but today was even more, the count reaching 16.  People who have been at the lab for years were saying that was the most they'd seen and started saying the film crew was a good luck charm.  We'll have more on that in part 2.

Anyways, Caribbean reef sharks inhabit the tropical waters from Florida down to Brazil and sometimes Bermuda.  They are listed as near threatened because they are overished in many areas and suffer the effects of coral reef degredation in others.  As far as human attacks go, there are only 27 recorded attacks all-time, world-wide attributed to Caribbean reef sharks and none have been fatal.

The sharks that you see here have been "trained" by the lab over the course of about 20 years.  They recognize the sound of our boat engines and gather together to get fed.  We are always very careful to do exactly the same thing every time we put people in the water here.  Everyone is strung out in a line holding a rope, shoulder to shoulder with no space in between.  The staff throws bait a few feet in front of the rope and the sharks feed as they please.  If a shark gets too close to us, we give them a good kick and they back off immediately.  This deliniates our space from their space and this video shows that for the most part the sharks respect that.

 

As you can see, the sharks mostly stay out about 5-10 feet in front of us.  Even when they come in close, just one kick will send them on their way.  They don't get mad and turn around and bite everything in site.  They do actually get into what is widely known as a "feeding frenzy"  but they don't include people in that party.  As soon as the staff stops throwing bait into the water, the sharks relax and just cruise around and we can drop off the line and swim with them for a bit.  You can actually get really really close at this point because the water is only about 20 feet deep so it is pretty easy to dive down and swim around with individual sharks like this guy.

It might look fake, but my camera is awesome.  You can't tell because of camera limitations but I was only about 2 feet behind this one and he just swam like I wasn't even there.

I practically dropped on top of this one and he just went about his merry way.  I got a sweet video swimming behind it for about 30 seconds but it takes a ridiculously long time to upload and I'm tired and it's late and I have to go running tomorrow.  But get excited, because part II of this day made it probably the greatest day of my life.  To be concluded...

The Longest Line

So I decided that I would only post when something cool happens.  The day-to-day stuff here is kinda dry for most audiences so I'll just keep it to things that have pictures attached that will get people's attention, like this one.

That is a 10.5 foot tiger shark that was caught on the long lines that we set yesterday afternoon.  A long line is basically a really long rope with floaters attached at intervals with hooks hanging off them.  Add some bait to the hooks and you have a long line.  Here, we generally set the lines at 2 pm, then check every 4 and a half hours or so.  Usually there are 6 people in the setting and hauling crew, then 5 in the checking crews.  Checkers go out at 6 pm, 9 pm, 1:30 am, 6 am, 10:30 am and then the haul at 2 pm the next day.  The schedule is a bit tough for the 1:30 crew, but most sharks are nocturnal hunters so the 9 pm and 1:30 am checks usually have the most sharks.

This was the setting crew.  There were a few stumbles at first but it was the first time for all of us so it's to be expected.  And we caught this spectacular tiger shark, so clearly we're awesome setters.

Anyways, after the 9:00 crew secured her and did their sciency thing they called back to the lab to get everyone out there for pictures and a quick snorkle.  Let me tell you, the first look at that face underwater stopped my breathe in my lungs.  This next shot gives you a bit of perspective on how big this shark was.

A bit about tiger sharks.  Tigers can grow to over 16 feet long, but usually top out at around 10-12 feet.  So this girl was a big one.  They can also weigh up to 1,400 lbs.  I'm lifting with all my strength here and I barely got her dorsal fin (the one on top that I'm holding) out of the water.  Moral of the story, this is a big shark.  That being said, people have the idea that they are deadly anytime you get in the water with them, which is entirely false.  You can count on two hands how many tiger shark attacks happen per year worldwide, which is an almost irrelevantly small number considering how many people swim in the ocean everyday.  Obviously you don't want to just jump in the water with one if you don't know what you're doing, but they're not out to kill all humans.  Even though we had it tied to the boat, this one never tried to thrash out or take a bite at any of us in the water and we got to within about a foot or so of her mouth.

After we all swam with her, the crew removed the hook and the tail-rope (exactly what it sounds like) and the shark calmly swam off into the night.  We caught a few more overnight (not me, I was on the 10:30 and hauling crews, which rarely get any) but none were big enough to get everyone out of bed.  We do this once a month, so look for another long-lining segment around this time in March.  Hopefully we'll get some different species and I can expand your education.  I have some pretty sweet shots of some baby lemon sharks so maybe my next post will deal with them.