Monday, 29 April 2019

Hooked on shark science - by Daniel Foley

Picture this scene: you’re a young college student from the Midwest having grown up fishing around tiny lakes and ponds your whole childhood. With a slight interest in ocean science, and curiousness as to what a living, marine goliath looks like, you accept an invitation to a small Caribbean research station in order to study shark science. A few days pass, and after plenty of safety lectures and brimming anticipation, there you are, staring into the eyes of a creature you never thought could exist beyond the realm of TV documentaries and YouTube videos. A 3-meter tiger shark caught on a thin looking piece of mono-filament rears its powerful body above the current. There’s that nictitating membrane we talked about in class! And the mating scars, they must be fresh! Adrenaline and serotonin mix in a fiery medley throughout your body. The shark is hooked, and so are you. This is the coolest sight you’ve ever witnessed in your life. And the people who work with these creatures? We have to become one...

Fast-forward three years: you’ve graduated with a fine degree and a steady job, but the wonder and excitement from years prior aren’t nearly sated. You come back to the research station as an official intern. Shark workups are now your reality; you get to hold the dorsal fin and witness firsthand the gargantuan strength of these creatures. You assist in the implantation of tagging devices, the sampling of blood, the finesse of surgery, the rush of tail roping. This and myriad more experiences are the reality of shark science, and you couldn’t be happier.

Lab manager James prepares to take blood from a large nurse shark (G.cirratum).
© Sophie Hart - Bimini Biological Field Station

Longline setting is by far the favorite activity, but the amount of work and patience necessary to capture a shark was lost on me as a course student. The preparation required for baiting hooks, affixing anchors and weights, navigating the lines (sometimes in the blackest nights!) is enormous, but so is the payoff. Seeing these sharks firsthand, working them up right alongside the boat and knowing that the work you put it is integral to scientific data that could change the course of a species’ existence is beyond satisfying. It was for this reason that I came back to the Sharklab, and I couldn’t be happier with my decision!

Monday, 25 February 2019

Longlines with Eckerd College - by Griffin Pinkus

I am one month into my internship with the Bimini Sharklab, an internship that I have wanted to do since I was in high school. It has been nothing like I expected when I was 10 years younger, but nevertheless it has been an amazing experience. For starters, the island is a lot smaller than I expected and I have been enjoying the small island life. The sun is always shining, the palm trees wave with the wind, and the water is a special kind of blue, the “Bimini blue” color that I have been hearing about. However, I did not come to this lab to soak in the sun and play in the water, though that is what it feels like sometimes. It feels like that because I have wanted to work with sharks since I was five years old, and you know what they say about loving the work you do – it will never feel like work.

There has been one day that has really stood out to me so far, and it will be a day that I will definitely never forget. We recently were visited by course students from Eckerd College and in order to show them a little bit of what we do we set up scientific longlines to show them how they are set and how sharks are worked up from a longline. Yet, with everything that I have learned with my time as a fisheries technician, nothing ever goes as planned with fieldwork.

We were originally going to set up the longlines at a location east of the North island, but with rough seas we decided to set the lines within a channel that leads to a lagoon. Our crew’s morale was high while we were setting the lines, telling jokes and having a grand ole time. Our whimsical nature quickly switched to a more serious note when we realized that we had a blacktip (C. limbatus) shark on the line. There was no more time to joke around and we worked diligently to finish the workup in quick time. While we were working up the first shark there was another blacktip that ended up getting hooked on another line. Once we arrived at the second shark and did the workup, low and behold there was a third shark on the line.

Inserting a NMFS (National Marine Fisheries Service) casey tag into a blacktip (C. limbatus) shark during a workup.
© Sophie Hart - Bimini Biological Field Station Foundation
Little did we know but this would be the start of seven back-to-back-to-back-to-back workups. There was no time between the sharks and we actually started to de-bait the lines so that the trend wouldn’t go on until nightfall.

Once everything was said and done, the mood of the team went from a serious note back to a lightened mood ending with an unbelievable high. In total we had four blacktip sharks and three lemon (N. brevirostris) sharks, and we never (at least since I’ve been here) have had that many sharks in such a short amount of time. All of the workups were done perfectly and quickly, with the students from Eckerd sharing the Sharklab teams' excitement as well.

Sunday, 27 January 2019

8-ray day - by Cailin Ervin

Since arriving at the Sharklab as interns, we’ve been responsible for collecting different elasmobranchs species for ongoing research projects. One of our target species is the southern stingray (H. americanus).
To find the rays we patrol shallow waters with skiffs and ideally when one is spotted we maneuver the boats and corral it towards the mangroves. Once in the mangroves people will slip into the water with nets and surround the ray, increasing the chance of a successful capture. When we land a ray we will bring it back to the boat, put it into a deep tub, and PIT tag scan it to see if we can bring it back to be worked up and logged into our data. However, the stingrays sometimes have other plans and make capture more difficult for us.
On “dark” days we come back to the lab without having caught a single ray.
Thankfully, our last trip was a little more exciting.

Scanning the mangroves for southern stingrays (Hypanus americanus)
© Sophie Hart / Bimini Biological Field Station
We started patrolling after lunch and quickly saw 2 rays swimming near the mangroves. Five of us hopped into the water and tried to outmaneuver them but with a burst of speed they got away. Same thing happened with the next three; one of them we were able to surround but it swam over the nets. The afternoon wasn’t looking too promising...

We were just about to get back into the boats when another couple of stingrays were spotted swimming in the shallows. Nets went into the water and we were raring to go. The first ray took off. The second tried to juke us, but we were prepared and easily surrounded her with the nets. We were finally able to land a good-sized female that we could keep for a work-up.
That first ray was the turning point for the rest of the day. One after another we kept catching more and more rays, some in close proximity to the one prior; I couldn’t believe they didn’t move when we caught others only 5m away. The last and 8th capture of the day was the most exciting.
Patrolling the shallows behind the lab, we spotted her swimming on the sand banks. Using the boats we tried corralling her towards the mangroves, but she wouldn’t have it. Everyone who could jump in did, to try and surround her in open water. The boats blocked her from either side if she went wide, while we stopped her from escaping to deeper waters. After 10 minutes we were able to loosely surround her; when closing in, she started to move up into the water column trying to go over the nets. Having one already getting away like that we were ready for it and easily scooped her up. 


A southern stingray is scanned to check for a PIT tag.
© Sophie Hart / Bimini Biological Field Station
Confirming via radio that we could take her back with us, we drove her the short distance to the pen and celebrated our amazing 8-ray day!


Sunday, 9 December 2018

Lucky gangion #15 - By Molly Kressler

Professional athletes speak often about the adrenaline high that carries them through challenging periods of athleticism. Ask a member of the Shark Lab to describe a longline-caught shark-workup and you will find the response matches the adrenaline-fueled recounting of professional athletes.
At the Shark Lab, you are extensively trained in shark handling and work-up procedures before you are involved with such an adrenaline-fueled act as a longline check and work-up. As a repeat Sharklab volunteer, I knew the exciting possibilities waiting for me on a 20:00 longline check. Making her way out the channel and around the eastern tip of South Bimini, Twin Vee carried us to the lines set across the mouth of the Bimini nursery. Sighting the first float of the first line, the adrenaline begins to slowly leak, as you acutely survey the line for missing or submerged gangions. Like the pro-athletes would describe, it’s muscle-memory: holding onto Twin Vee’s rail while leaning out to sight each gangion, or as we all hope, to not sight one, the gangion float having been pulled under by the weight of one of Bimini’s several possible shark species.
To the astonishment of the crew, we had three blacktips (C. limbatus) that night, all caught on the fifteenth gangion of their respective line. By the time we finished the first work-up, the air was palpably buzzing, smiles and high-fives were shared by all. But with the shark safely off the side of the boat, the adrenaline began to slowly dissipate, and the attention was returned to scanning the lines for another submerged gangion.

A blacktip shark (Carcharhinus limbatus) being worked up during a longline check.
Photo by Sophie Hart | © Bimini Biological Field Station Foundation
When we came upon the second black-tip, again on gangion #15, the buzz returned. Flood lights on, the team moved swiftly to bring this female up to the side of Twin Vee. I elected to hold her first dorsal fin, working to secure her position in the water, so the rest of the team could perform the various work-up measurements and samples as swiftly as possible. It was holding this female’s dorsal where I had a unique opportunity to see very fresh mating scars. The female’s dorsal side was littered with bite-marks. Elasmobranchs can heal their wounds remarkably fast; this female’s wounds hadn’t healed over yet, which indicated the mating event had occurred recently. Moments like this, a shark less than a metre from your face, with the types of ecological evidence you normally would only be able to see from metres away, are the adrenaline-filled moments that litter your months at the Sharklab.
The night proceeded with a third blacktip on another line’s gangion #15 – the boat erupted in astonishment. Smiles and laughs quickly turned to well rehearsed action, as another episode of swift data collection was underway. Eight minutes blitzed by and with another successful work-up complete, so too another blacktip swam away from Twin Vee, an official member of the BBFSF tagged-elasmobranch club.

Tuesday, 27 November 2018

Beyond the Tag - By Clemency White (Principal Investigator)

When you think of what shark scientists do, it usually conjures up images of tagging sharks and tracking them. Your mind immediately goes to the classic images of a team of scientists working quickly to tag and release huge sharks, it’s always a beautiful clear blue day, there are high-fives all round as the shark swims away with its new tag in tow. But how often do you consider what happens after that? How do we use the data that we get from tracking tagged animals to inform science? Welcome to Bimini...!

The Shark Lab team perform a work up on a Tiger shark (Galeocerdo cuvier) captured on a scientific longline.
© Sophie Hart / Bimini Biological Field Station
Since 1992, under the watchful eye of Dr Samuel Gruber, scientists at the Bimini Biological Field Station, “Shark Lab”, have been using data from tracking tagged sharks to answer a whole host of questions. We know that juvenile lemon sharks can swim back to their nurseries from as far away as the Gulf Stream. We know that space use is tidally linked, and juveniles will change their space use depending on whether or not predators can access the habitat they are using. We know that while adult females use Bimini to give birth, males are transient, rarely returning to Bimini after they reach sexual maturity. All of this is made possible by analysing the data obtained from tagging and tracking, particularly in long ranging marine species where physically following them by drone or boat is near impossible.

A juvenile Lemon shark (Negaprion brevirostris) swims by at one of Bimini's mangrove nursery areas, Aya's Spot.
©
 Sophie Hart / Bimini Biological Field Station Foundation
Over time, these datasets become even more valuable, and that’s where I come in. One of the reasons Bimini is such a special place is because of the long-term data that has been consistently collected in a standardised procedure for almost 30 years. Collating and analysing this data in one go allows us to confirm trends we have proposed from shorter studies and make new suggestions based on temporal change. While it may not be as glamorous as spending every day out on a research vessel in the Caribbean, there is a lot to be learned from spending your time running statistical models behind a screen.

During the two months I spent working on a dataset that spanned 26 years, surpassing my own age, I employed a statistical modelling technique that allowed me to see how different groupings of lemon sharks were using space. Most profoundly, I established that the space available for use by lemon sharks was reduced as a result of industrial development in Bimini. A thorough understanding of a species life history is imperative for sound conservation management techniques, and so studies like this one are instrumental in translating science to policy. This also highlights how important it is that we continue to tag and track sharks at all life stages.

So, next time you see one of those awesome pictures of sharks being tagged, consider the questions that the tag itself can answer, and how we can move forward in science and conservation - even after that shark swims far out of sight.

Tuesday, 20 November 2018

‘Turtle Day’; A visit from the FSU MTREC group - By Amanda Schadowsky

August 23rd, 2018 was the same as any morning at the Shark Lab, but for me it will forever be referred to as ‘Turtle Day’. We had visiting research assistants at the lab, from the FSU Marine Turtle Research, Ecology and Conservation (MTREC) Group, who took volunteers with them each day to assist in the field. On this particular morning a fellow volunteer and myself were selected. I was very excited because this was something new and I assumed that all the work I would be doing here was going to focus only around sharks.
After breakfast we got ready for working out in the field and grabbed the equipment we needed. We packed up the skiff and took off for the day to Bonefish Hole, a new location that I had yet to work at.
The sun was out in full effect surrounded by a picture-perfect blue sky and minimal clouds. The water was so clear, and the turquoise and blue color gradients starting from the mangrove edge was a perfect representation of the Bimini waters. I remember thinking to myself that the view was insane, and I couldn’t believe that I had the opportunity to live and work in such a beautiful place. 

As we were entering Bonefish Hole we were told to scan the water for green sea turtles (Chelonia mydas). This is where polarized sunglasses are important, so when the Shark Lab advises you to bring them, do it. The combination of the sun glare and waves makes it hard to see if you don’t. If we saw a turtle, we were instructed to point it out and the chase would begin! The turtles would try a few different tactics to get away, weaving, changing direction quickly, and sometimes completely stopping, camouflaged in the sea grass. They were quick, and we were on a small skiff, so it felt like a high-speed chase in an action movie. Once the boat was close enough, someone would shallow water dive off the front-side onto the turtle. Us volunteers were given opportunities to dive and try to catch one; unfortunately we were not as successful as the professionals! 

FSU MTREC researchers Alexa and Anthony take measurements on a green sea turtle (Chelonia mydas) during a work-up.
©
Sophie Hart
Once we had a few turtles in the boat, we then did work-ups on them. Measurements were taken along with small biological samples. While one turtle was getting worked-up the other turtles would make their way to the front of the boat, seeking refuge from the sun under my legs in the shade. It was truly a heart-warming moment to be near sea turtles. After the work-up was done, we were able to get photos with the turtles before releasing them. 

Turtle Day wasn’t an intense day. It wasn’t a day swimming with Bulls, Lemons, Reefs, or Tiger sharks. But, it was a day I will never forget.

Tuesday, 30 October 2018

Capture, Work-up, Repeat; a day in the life of a Shark Lab intern - By Laura Manning

The plane was boarded and it was time for our flight to Bimini. I peered down upon crystal-clear blue water and thought about the adventure I was in for. The past three years of my life, I have traveled around a variety of countries, each with their own unique species of flora and fauna I have had the opportunity to work with. I decided to come intern at the Shark Lab to gain even more field research experience.
We were given instructional classes by the staff the first week to help train us for tasks we would be doing out in the field. These included boat class, knot tying, and my personal favorite, shark handling. This class consisted of each intern demonstrating the proper way to hold a baby lemon shark. Being able to properly hold a shark is essential for capturing and performing work-ups on the shark.

There are a variety of capture methods used depending on the target species. To catch nurse sharks, the technique we use is called “nurse wrangling”, where we take a skiff out to reef ledges. Our goal is to find a young nurse shark typically between 50-80 centimeters total length that we can bring back to the pen to work-up. If we do find one, someone will free dive to the ledge, place their hand between the gills and pectoral fin of the shark and swim it up to the surface. It will then be placed in a tub of water and taken to the pen at the lab.
Scanning the reef ledges for juvenile nurse sharks.
© Sophie Hart

Stingray capture is definitely a “practice makes perfect” kind of a job. It requires one person to slowly drive a skiff along the mangroves and have 3-4 people standing on the bow of the boat scanning for stingrays. If a ray is spotted, the driver needs to steer towards the mangroves so that the others can jump in with dip nets to corner and capture it. Often, the ray will bolt or make circles as the skiff is attempting to follow it. The rays’ coloration provides a great camouflage with the murky mangrove waters, so spotting can sometimes be quite tricky. If a capture is successful, we place it in a giant tub filled with water and drive it to the pen to be worked up a few days later.

Gillnetting is the best way to collect juvenile lemon sharks for research. The gillnets are strung across the pond from one side to the other, with two people taking a bucket and walking along the net scanning for sharks. We do this every 15 minutes over the course of a few hours. If a shark is caught we rush over to it to quickly release it from the net, place it in the bucket and take it to the pen. If the capture is successful, we will perform the work-up within a few days. Until then, we will gill net fix! The holes are often large and fixing them requires a ton of mono and sitting in the sun making numerous fisherman’s knots, over and over…..

While these tasks can be difficult and tiring, they are all an important part of field research and are essential to better understanding elasmobranch species. Each day at the lab we learn something new and are able to continuously apply the skills we learn throughout the course of the internship. I can safely say I have learned so many techniques that will help me to become a better field scientist for any future research that I pursue.