June 5, 2007

A reef shark eyes some bait

Today was another day of rest and a chance to finish up any minor details in gear preparation since we are resuming our fishing schedule tomorrow. We did want to do another shark dive today and set to work filling up a bait cooler for that endeavor. The click-click-click of the bait hatchets at work sounded across the lab backyard and the cooler slowly filled. Anchors lines and extra gas were loaded on the boats and before long we were hurtling across the flats towards the shark dive site at Triangle Rocks. When we arrived at the site, we could see several large sharks patrolling the area and they looked very interested in our activities. The sharks in this area are quite familiar with being fed by us, and they proceeded to dart around in anticipation of the bait hitting the water. The sharks seemed extra lively today and we appeared to be in for an exciting feeding session.

Snorkelling at "The Arena" site

There were definitely some large female reef sharks there today and they were very energetic. The larger sharks made pass after pass engulfing chunks of bait and chasing the smaller sharks off. The presence of the larger sharks definitely had an effect on the smaller sharks, as they were on full alert and would make quick sprints into the feeding area to snatch a piece of bait and then dart off before they were harassed by the larger sharks. The competition heated up as several sharks would converge on a single piece of bait. The frantic activity also made the sharks a bit bolder than usual and there were several times when they appraoched very close to the snorkellers in the water and had to be reprimanded with an assertive swim fin tap. It really gets the adrenaline going when several large sharks make a beeline for you and then at the last moment veer off in a violent puff of bubbles. The team was treated to a brilliant exhibition of the grace and power that sharks naturally exude. The good shark dive left the entire team hungry to get back into the field and start catching sharks again. The team spent the remainder of the day at their leisure, as tomorrow would be a big day. We planned on getting up very early and setting a deep water longline until mid-day, and then resuming our fishing with the first night of the North Sound nursery area. Tomorrow could prove to be an amazing day as we never quite know what we can catch around the island.

A reef shark darts through a group of triggerfish

June 6, 2007

Preparing the polyballs for the deep line

We arose a little before 4:00 AM and got the last few bits of gear together and loaded up the aquasport. We took a couple extra minutes to set-up the trandsducer for our depth sounder and proceeded to head out west of the island. The plan for this early morning was to set a deep longline for a few hours and see if we could catch some sharks from deeper waters. To accomplish this we set an anchor and cynder block weight to the bottom in approximately 500 feet of water. After letting out over 800 feet of line we started attaching large polyballs and long gangions to the line. The gangions were setup so that they would hang the baits at a depth that was close to the bottom. The gangions terminated in a length of steel airline cable, with weights to keep it down and a barracuda bait on a large circle hook. The finishing touch is a cylume - a green glowstick, that should picque the shark's interest in the dark depths. The gangions on the ends of the line also recieved a bag of custom made Sharklab chum - an aromatic recipe of oats and fish oild, with some punctured cans of tuna thrown in for good measure. To get the line out in an efficient manner, we partition out the work so that everyone has one single task to focus on and the set progresses like an assembly line.

Tiffany prepares a gangion

We utilize an electric winch to raise and lower the main line. The lines are long and have heavy weights to keep the baits down, so this is a welcome luxury. One person each is assigned to the tasks of baiting hooks, adding weights, preparing chum, attaching the gangions to the main line, and tossing the large polyballs overboard. The poeration worked fairly well after an initial problem getting the anchor to set. We anchor one end of the line and let the other end drift free. As the set progressed, the current really started to pick up. We let our boat drift along the line, then started the engine up and drove back to the beginning of the line to drift by it again. We were excited at the possibility of seeing some large or unusual deepwater sharks, but the polyballs refused to give any hint of a potential shark capture.

Sharklab brand chum

Steve and I got in the water to give the lines a quick inspection in the strengthening current. We freedove down about 30-40 feet to get a good look at the gangion lines. Unfortunately, the gangion lines were sitting at a very acute angle to the main lines, and this means the current was significantly strong enough to pull the gangions out. This presented a distinct problem, as the pull on the gangions would cause the hooks to come well up in the water column, and not allow them to be situated just off the bootm as per our intentions. As we were swimming around, a small visitor appeared to check us out. A small, one meter silky shark made several passes around us to satisfy its curiosity. Steve had never seen this species before, but I recognized its slim profile, tiny second dorsal, and inquisitive eye right away from many previous encounters. The silky buzzed us a few more times, even swimming right between us at one point, before turning and silently dissappearing back into the blue. Steve and I returned to the boat and began to dry off. As we looked at the polyballs we realized something was wrong.

A small silky shark says hello

They had been fighting to stay above the water in the strong current but were now sitting placidly on the surface. We also noticed that we had drifted north of where we had set the line, and were now offshore of the north island. The line had come free from the anchor and we were drifting along. A storm was also moving in, and we decided to haul the line with mother nature's deep baritone notes rumbling across the darkening sky. We were able to get all the gangions and polyballs packed back into the boat and then went to haul in the main line. A little way down the main line from where the last polyball was located we found a snapped end. The stress from the pull of the strong current on the line must have caused the line to snap. If you are scoring at home, our set came in with sharks 0, anchors -1, and main line -700 ft or so. Despite the equipment failure, we learned quite a lot from the set and will be able to refine and improve our methods for the next time. We will be better prepared the next time we set a deep line, with more weight on the gangions, and this methodology should prove to be successful in the future.

It seems we had already put in a full day's work but it was just after mid-day, and we would resume our fishing efforts this evening. We spent the afternoon resting, and I was able to take an absolutely epic nap. As late afternoon rolled in, everyone got up and began making final preparations to return to the field.

The nets are in the water...again

Night one of the North Sound nursery always seems to be exciting, and this year was a far cry from a dissappointment. Anticipating a busy night full of sharks we had loaded the away team with experienced personell. No matter the magnitude of a rush of sharks, the veterans would be able to keep cool heads and be able to respond. The night began with early shark catches and looked to be a promising night. The nets consistently produced sharks. All the nets were busy, but Net 1 was particularly being put to the test. They were in the thick of a run of sharks when they discovered a huge surprise in their net, a smalltooth sawfish. This was the second sawfish captured by the team in as many weeks, and a rare treat. I fully "blame" Christian for the capture. He must exude some magical attraction to these mysterious beasts, as the only two nights he spent on the nets both produced a sawfish capture.

Christian holding a smalltooth sawfish

The Net 1 crew did an amazing job of safely extracting the sawfish from the net while continuously dealing with additional shark captures. This is exactly the type of situation that can arise that demands the team to be on top of their game. Back at the lab, the homecrew was just getting ready to set out with the dinner runwhen the sawfish capture was radioed in. After a brief conference between the staff, a decision to place an ultrasonic transmitter on the animal was reached. Since this was such a rare and amazing event, we wanted to make the very most out of it, and hopefully get a glance into this animal's elusive existence. It was a fortuitous coincidence that we caught the animal at this time, as a boat was all set to go and we could quickly grab the extra equipment needed to work up and tag the sawfish. I will never forget the excitement I felt driving the boat up into the lagoon that night. It was a calm and beautiful night, and we were about to have the chance to tag an uncommon and enigmatic species - one of those remarkable experiences that few people ever get to grasp with their hands and the truly what we live for as biologists. I hope I speak for everyone when I say that I would happily trade weeks of sewing gillnets, working on pumps, coercing the truck to roll yet again, or any of the 100 other menial but necessary tasks the lab provides, just to get that one glimpse of the biologically extraordinary. Personally, it is the reason I keep returning to the lab, the possibility that I will see and experience something truly wonderful (and if I am so lucky, to photograph it).

The team works up the sawfish

We were fully prepared to get as much data as we could from this animal and arrived on the scene to seize the opportunity. It was a little tricky, but we were able to get the sawfish secured to the side of a skiff via a custom fabricated makeshift harness from boat lines. Once the animal was secured, we could proceed to work with it. We still had to pay extra attention to the long, tooth-studded snout, as the sawfish could still wave its nose around if it thrashed. Once it was nestled in the harness, the sawfish seemed to calm down, and we worked carefully but quickly. We took measurements of the length of its rostrum (snout), its pre-caudal length, and its total length. This specimen was a 264 centimeter female. She had twenty-six pairs of teeth along its rostrum, confirming it as a smalltooth sawfish (as distinguished with the largetooth sawfish, which has fewer pairs).

The sawfish sits calmly by the skiff

After measuring the sawfish, we took a small clip of its fin as a DNA sample. Two separate tags were attached to the sawfish, a NMFS Casey tag and a Sonotronics acoustic transmitter. The transmitter is set-up to work with two different telemetry methodologies. We can hear the transmitter with hydrophones and manually follow the sawfish around to get a track of its movements. Additionally, the transmitter will be picked up by bottom monitor units distributed across the lagoon, so that if the animal enters the lagoon and passes near a unit, the monitor will record its presence. The smalltooth sawfish is not recognized in Bahamian waters in published literature, and getting data on the continued presence of a smalltooth sawfish could be very important. The first night of the North Sound was a resounding success. Not only did we complete potentially important research into the smalltooth sawfish, but we managed to capture fifty-five healthy juvenile lemon sharks.

Portrait of a sawfish

June 7, 2007

Another night of gillnetting begins...

After all the excitement of the preceding night, the team was looking forward to a less strenuous night in the field for night two. We still expected to get a decent amount of sharks, but expected a significant dropoff from the first night. We were also a little apprehensive about the possibility that the sawfish was still in the area and could potentially get entangled in a gillnet again. Our reserveations thankfully proved to be unfounded and we had no further encounters with our toothy-nosed friend. This of course did not mean that the night lacked its share of action. It was only the second night of the nursery and there were still a good number of sharks swimming around that could find their way into our nets.

The pen is filling up with lemons

We juggled the teams up a little to bolster the home crew and make sure that every team member gets time in the field. The new teams were treated to a mild, clear night with a weak breeze. The weather equated to good working conditions, and there was just enough wind to keep the numbers of mosquitos down. Nights like these can be really calming, as it is always a pleasure to enjoy the tapestry of stars between net checks with a minimum of harassment from the bugs. The net checks were also productive, and seventeen individuals swam into the nets overnight. This was an enjoyable night because there were still plenty of sharks to work with, but they came less rapidly than the evening before. The team came back in the morning with a very upbeat attitude, as night two continued our streak of success. We now have seventy-two juvenile lemons secured in our main pen, a number that already makes this a good year for this particular nursery.

June 8, 2007

Checking on our friends as another night begins

The sun starts dipping down towards the horizon and the away team sets off for another night on the nets. The weather has taken a slight turn towards the ominous. It is relatively overcast, and the waning light levels makes for some dramatic contrast in light and dark grays in the evening sky. Under this monochromatic canopy we pull up to the pen to check on our temporary captives. This is a simple task that needs to be done every day when we arrive in the lagoon. We monitor the sharks intermittantly during the night as well. Every hour or so, someone on the tagging boat dons snorkel gear and grabs an underwater light (or torch, as our team members from the land of tea, Tories, and Tony are apt to call it) in order to take a late night swim in the pen. Being in the pen with the sharks at night can quicken your pulse, as the sharks are attracted to the beam of light coming from your hand and you find yourself playing a strange version of "chicken" as you and the sharks swim at each other.

Checking the net via the skiff

On each of the nets, the boat captains work the skiffs along the length of the gillnet while they still have enough water in the tide. Every fifteen minutes you can hear the Mercury outboard spring to life and we flip the 100,000 candle-power Q-beam light to see our nets. We slowly drive along the float line, and the powerful light allows us to see all of the net down to the bottom. The crew keeps their eyes out for sharks, while the captains concentrate on navigating the skiffs. You need to keep the skiff close to the nets to get a good look at them, but want to avoid catching a "propeller fish". The lagoon is also shallow, and you have to make sure you have the engine tilted up to avoid the bottom when you get inshore towards the mangroves. As the tide inevitably falls, your ability to drive the entire net finally ceases, and walk checks begin.

Kat & Candice in muffin-producing euphoria

Back at the lab, the home crew is having fun too. With the dinner successfully sent out to the away crew, and energy levels still high, a few of the girls decide that some baking is in order. As a surprise to the away crew, we will prepare a special treat for breakfast. Instead of one of the usual breakfasts of toast, eggs, or pancakes they will be treated to freshly baked muffins. Kat decides to "kick it up a notch" and throw some chocolate chips into the batter. I have always been a huge fan of chocolate for breakfast and I am looking forward to the little treat in the morning.

The night goes well althought there is some rain and the away team comes back a little soggy in the morning. At least they have fresh muffins as a reward for their hard work. The net action was a bit slow, but we managed another five sharks. The fishing in the North Sound is now halfway to completion, and we have seventy-seven healthy sharks swimming around our pen. We will now look forward to a day of rest before the home stretch - the final three days of fishing.

June 9, 2007

A lemon greets Mark & Co.

Today is a day of rest, or as previously explained, a day to catch up on net repair and stay out of the lagoon to allow sharks to move around a little bit to hopefully increase our chance of catching them. The away team gets to get some sleep and recharge their batteries a little. Today we are also getting a few visitors. We will be having a family of three stay at an apartment near the lab on the island, and will hopefully be showing them some of the facets of our shark research here at the BBFS. The gentleman in question is named Mark, and works for Destron-Fearing (a division of Digital Angel). Destron-Fearing manufactures the PIT tags and PIT tag readers we use to implant and identify individual sharks. We have a long relationship with Destron, as we have used the PIT tags for over a decade as our primary means of tagging juvenile lemon sharks here in Bimini. I think this will be an exciting opportunity for Mark and his family, and we have several activities planned for them. We hope to provide him with a new perspective on his familiar technology - allowing him to truely "get out of the office" and see how the equipment is used in the field. Not wasting any time, we aim to get them in the water the first day. The goal of our mini-expedition is to feed the lemons in the pen, so we take snorkel gear and pile Mark, his wife, and their son into a skiff and zoom up into the lagoon. We take them into the pen and let them watch the lemons being fed. At first they were a little apprehensive, but soon they were making excited cheers each time a lemon took a piece of bait. It appeared that they all had a great time and it was an intense but good way to introduce them to our work.

Taking a small break from our hard work to relax

They say that all work and no play makes for a dull life. While life at the Sharklab is anything but dull, we have been working pretty hard to this point in the project and the team is showing some signs of being a little tired. Doc has been running this project for a long time and knows exactly how to keep the team running in top form. Since we are not fishing this evening he sees the opportunity for us to relax and let off a little steam. Doc announces that we can make the short walk to the Beach Club to see the band, watch TV, or have a drink. We can then sleep in a little tomorrow. I think this is the perfect thing to recharge our batteries for the final stretch, and apparently everyone on th team does, as we all make the journey down to the Beach Club.

The lab is about friends as much as sharks

Even Doc comes down for a little while to relax with the team. A big group develops around the ring toss game. This game is very popular in the Bahamas, and involves having a hook on a wall with a ring suspended via a rope from the ceiling. If you have the skill, you can swing the rope so that it just reaches and catches the hook on the wall. You can always tell the members of the team who have spent considerable time at the lab, because they are in practice and true snipers when it comes to ring toss. We happened to be extra lucky, as our night off falls on a Saturday and the band was playing. There are also lots of tourists in town, as it is a weekend in the summer. The Beach Club is a very welcoming place, from the warm smile of Bob, our favorite bartender, to the smooth Caribbean rhythms, to the warm tropical nights experienced from the lounge chairs by the pool. It is definitely an environment conducive to the sort of respite we desired. The team can dance, play ring toss, watch sports on TV, and generally talk, laugh, and have a good time. We then get off to bed for a good night's sleep. We are ready for the last three days of fishing - bring them on!

We will be ready to catch more sharks...

June 10, 2007

Caribbean reef sharks cruise by...

We wake up this morning with a few odds and ends to do before we are all set to embark on fishing again tonight. We double check the last of our gillnets for holes while we wait for the right tide. We have a sharkdive planned around noon. We get the bait, extra lines, extra anchors, fuel, and our snorkel gear all set to go. the boats are packed. I take the Aquasport out to Triangle rocks. It is an absolutely perfect day, the seas are calm and flat as glass. You can see every blade of seagrass and small piece of coral through the crystal clear waters when there are no surface ripples. The boat flys on the still waters and i sit back and enjoy the warmth of the sunshine on my shoulders and sensation of air moving over my face and through my hair. This is the type of day I live for and I am esctatic that I am on the water. We reach Triangle rocks and get all the anchors set so the boat sits next to the sandy bowl we call "The Arena". We already have a few interested friends, and we can see their dark forms circle the boat.

A close look at a reef shark on the sharkdive

Everyone entered the water and lined up along our surface line. Mark helped us throw the bait to feed the sharks. He seemed to be enjoying himself more than the people in the water. The calm surface allowed for a clear view of the sharks as they sliced in to engulf pieces of the bait. Their fins broke the surface and cut small white swathes through it. Every now and then there was an eruption of spray and foam as multiple sharks went for the same piece of bait and a tail broke and crashed on the surface. We showed Mark where to throw the bait to move the sharks in and out from the snorkelers. He picked up on it quickly, and was soon orchaestrating the dance of the sharks like a seasoned maestro. The sharks were quite frisky today and put on a great show. Too quickly though, we had thrown the last piece of bait, and would leave the sharks to hunt on the reefs again.

Distributing warm food to the masses

We begin night four of the North Sound fishing effort. The nets hit the water around 6:30 pm and the team bunkers down for their night "at the office". The wind has died down considerably and there are a few mosquitos out. i don't think anyone can ever get used to that annoying buzzing sound of a mosquito (or worse yet a chorus of them). However, we are well versed in our fieldwork and prepared for this contingency. We all don our personal variety of mosquito gear. There are billowing mesh, hats, shirts, jackets, pants, and even full tents. We must look a little ridiculous, driving around the lagoon through the night geared up like nomads out of the Arabian Nights. However, it beats being dinner for the mosquitos. Our fortitude pays dividends in landing an additional eight sharks to the fold. That brings the count up to eighty-five sharks for the North South. That is already a healthy number for this section of the lagoon and we have two more nights to add to the total.

June 11, 2007

Mark gets to scan a shark

Today we had a special treat planned for Mark. We have kept a couple of sharks that we caught last night in one of the small pens, and would be heading up to the North Sound to work them up with his help. The highlight of this excercise would be that Mark would be able to use the Destron PIT tag reader in the field on the sharks. He seemed really excited, so we didn't delay once we had all the gear ready and headed up to to lagoon. Once there we got all our equipment set up and explained the work up process. We caught each individual shark and put them in the measuring trough. We were lucky enough to get an untagged shark and a recapture in the group. Mark was able to see us insert a tag and scanned the shark to confirm its identity. It only took us about half an hour to process the sharks and return them to their pen but I think it was highly worth it by the big smile on Mark's face. It must be rewarding for him to see his company's products in action.

Tristan secures the gillnet for the set

The weather is dark and cloudy and looks a bit ominous. We make sure to pack our rain gear in case of showers. The wind has picked up, which means no bugs tonight. I would much rather have rain than mosquitos. By the time we head up to the lagoon for the set, the sky has darkened some more but there is light on the horizon. The effect is quite dramatic and beautiful as it looms over the green tract of mangroves to the east. This is another one of those moments when you feel like Mother Nature is giving you a small reward for your efforts in the rain, cold, sun, mosquitos, or anything else her caprice decides to throw at you. We get the nets in the water around 7:00pm just as dusk is settling in on the lagoon. Shortly after the set, we get a quick shower, but this dousing would prove to be the only one of the night. Spared of bad weather, we set to work, driving the length of the nets over and over and plucking sharks out when we get the opportunity.

Nick diligently checks the net

We had some extra help this night. Mark's son Nick wanted to come out and help us with our field work. He has a fascination with sharks and wants to be a marine biologist in the future. He wasn't shy and dove right in to help us set, check, and haul the nets. He was a real trooper, staying awake with us all night as we fished. It was a pleasure to chat with him - he knows a lot about sharks. He obviously has read extensively on the subject and if there is a place in the world to talk sharks it is on a BBFS net boat. I think Nick really enjoyed the experience. Maybe in a few years we will have to have him back as a volunteer... this is the second to last night, and the odds are that we have caught almost every shark in the lagoon, but we manage to nab another three. That makes eighty-eight sharks total for the North South this year. We may add another one or two sharks tomorrow night, but it should be a fairly slow night. The team is excited for the final night of fishing and completion of the PIT census.

June 12, 2007

A mini-cyclone of lemons "fish-milling"

Well this is it, we have finally reached the last night of fishing. One final effort and we can sit back and admire a job well done with a relieved sigh. The weather is still overcast and dark, but spirits are running high. We head out to the lagoon in our usual armada. We check on the sharks in our main pen. There are quite a few individuals in there, but ther all seem quite happy and are swimming energetically. Many of them can be seen to be swimming in a large whorl of sharks. This behavior is quite common in fish and they tend to swim from one end of the pen to the other and mill at the ends. This is one of the reasons we build the pen in a large oval shape. I could never get tired of watching the lemons swim. They really are graceful animals, gliding through the water with a poise and purpose that is unassumingly evident. Satisfied that the sharks are all doing well, we turn our attentions to setting the nets.

Putting the net out for the last time

We have Nick's help again for tonight. Apparantly, we didn't bore him too much with a night of sitting on the boats with us and he is back for more. Tonight we were not as fortunate as the previous night, as the sky has decided to make its prescence felt. It was a little wet, but the countdown had begun. We knew that we would be seeing a lot of empty nets tonight, but that was a good indicator that we had captured almost every juvenile lemon shark utilizing the lagoon. The wind picked up and the surface of the lagoon got a little choppy. When this occurs, it can be a little difficult to see the nets and be certain there are no sharks trapped near the bottom. The simple solution is to do slow, careful walking checks of the net, which since we were already wet, made perfect sense. The hours trickled by and The food boat came out to bring us both a warm and welcome meal, but a short respite from the routine of net checking. We headed over to the main pen and all the net boats were there. Although it was short lived, it was nice to have the whole team there together to enjoy our last meal in the field for PIT. We were wet and a bit tired, but the finish line was in sight.

Walk checking the empty nets on ther last night

We had a little excitement in the wee hours of the morning, as the net closest to the mouth of the North Sound managed to snag two sharks. Those would turn out to be the only stragglers of the night though, and when we pulled our nets just after dawn there was a grand total of ninety lemons in our main pen. The nets were packed in their boxes and the census fishing was officially in the books. We still had a couple of days to clean, repair, and stow gear but the major work was over. As a small reward, we planned on setting a couple research longlines, and hopefully catch some big sharks. Everyone always gets excited to longline, and I really hope we can catch a few sizeable tiger sharks. They are one of the most attractive fish I have ever seen and many of them tend to wander the banks off to the east of the island. For now we will get a couple hours of rest and wake up to set the lines.

June 13, 2007

Mark giving the nurse an exam

There was a buzz of excitement coursing through the lab as we all arose. We are all really looking forward to setting the longlines and curious about what will show up on the hooks. We set five lines with fifteen hooks apiece. We set four of the lines to the east of the main lagoon. These lines are designated lines A, B, C, and D respectively. We then vary the location of the last line which we call the "wildcard". For this set we are going to set the wildcard to the south of the south island. The longlines are set up with a length of strong and thick cord held in place by anchors and cinder blocks at both ends. Strung along the lines are a series of floats, large pink ones to demarcate the ends of the lines ands white floats spaced at a set interval. Bewteen the white floats a gangion is attached to the main line. A gangion consists of a baited circle hook, length of airline cable, float, hook timer, length of cord, and finally a tuna clip. The tuna clip can slide along the main line, allowing a hooked shark the ability to swim over a small area. This reduces the amount of stress the animal experiences, as well as allows species that need to swim in order to breathe the opportunity to do so. we want to capture, tag, and release live sharks so we check the lines every four hours to limit the amount of time a shark can be on a hook. Aditionally, we use exclusively circle hooks, which tend to slide to the corners of a shark's mouth when they set. This reduces the amounts of hooks swallowed and the general amount of injury a shark could sustain.

Joey finally sees a tiger shark

We prepare the Aquasport with all the tagging gear and I pull the boat out into our channel. Off into the inky, black moonless night we go, with anticipation levels at a fever pitch. After a little confusion with our GPS, we finally locate the first line. The first line yeilds a couple large nurse sharks. Nurse sharks can be a little difficult to work with. They are strong, and tend to do "death rolls" spinning themselves and getting all wrapped up in the lines. You have to be careful you don't get anything wrapped up with them, as the pressure and the airline cable could cause a serious injury. The skin of the nurse sharks is very rough and you can abrade your skin easily. Getting the tag into a nurse shark can sometimes be an ordeal because their skin is so tough. However, we have an experienced crew on boat and the workups go very smoothly and quickly. When we check the lines we look for the gangion floats bewteen the spaced large floats. If a gangion float is missing ("down") then the odds are there is a shark on the hook. Once we have confirmed that we have captured a shark we use the gangion to tie the shark alongside the boat. A special lasso called a tailer is then used to control the tail. We tie a noose around the animals tail and then it is secured at both ends. It is now fairly safe to work with the shark. We take length measurments, identify sex, and tag the shark with a NMFS casey-style tag. Once the workup is completed, we remove the hook, and gently ease the noose off the tail. A gentle push and the shark is back on its way to cruise the lagoon and/or banks.

A prize catch - a tiger shark

We get through the nurses and head out to the east to the regular lines. It only takes us two hooks on the first line to get exactly what we were all hoping for. A large, dark shape is towing the gangion around, and as it comes close to the surface, we can see its broad snout identifying it as a Galeocerdo cuvier, or simply - a tiger shark. Joey is on the team, and I am particularly satisfied because although he has been on many longline teams the tiger has found a way to elude him. Although they are juveniles to subadult tigers, these sharks exude power and authority in a way that supercedes other sharks. They usually are a forest green with silvery-white undersides, and their sides have the distinct barring patterns from where they derive their name. We call the lab so that everyone can come out and see the shark. After working it up, I briefly hop into the water to take some portraits. By now the other boats have arrived and there is a group of snorkellers around to see and revere this amazing animal. We have more lines to check though, so we remove the hook and let the shark go. The tiger gracefully and slowly sinks towards the bottom where it makes its way leisurely out of our circle of lights. We catch a couple more sharks on the other lines - more nurse, a couple blacktip, and another small tiger. Finally, we reach the last line where we get a very welcome surprise - a subadult lemon shark. Despite their prevalence in the lagoonal areas. lemon sharks seem a bit reluctant to take the baited hooks, and capturing them is an uncommon event. A lemon presents a unique opportunity, as not only will the shark get a PIT tag, but it is a perfect size to put an acoustic transmitter on. The main predators for the juvenile sharks are larger sharks. The BBFS has an array of hydrophone monitors spaced out across the lagoon. By attaching a transmitter to subadults, we can track where and when they pass by various recievers. This may help us to determine patterns of usage by the larger sharks and more successfully estimate predation levels on the juveniles. Overall we spent almost four hours out in the field to check all the lines. Upon our return to the lab, exhaustion sets in, but we are able to get to bed with huge smiles on our faces.

Subadult lemon gets a transmitter

June 14, 2007

Catching sharks to attach transmitters

We wake up to see that the other longline teams were able to catch some more sharks during the night. There will be two more checks today before we haul all the lines. The lines are usually set for a period of twenty-four to forty-eight hours (though we put fresh bait on the hooks every twenty-four hours). The main activity of the day, scheduled after a line check, is the release of the North Sound lemon sharks from the main pen and subsequent pen demolition. We have a few select sharks to find first and attach transmitters from before we can release them all. We head up to the pen in full force - five boats and all personell. Everyone will be involved in this activity, as it requires both lots of manpower and has the personal reward of seeing all the sharks we worked so hard to capture finally released back to freedom.

Preparing to herd the sharks out of the pen

It takes us a little while to find, isolate, and catch the individual sharks and properly attach the transmitters. We then set up the seine net in the pen and slowly herd the lemons out into the lagoon. Some are suprisingly reluctant to leave, even turning around and swimming back into the pen after they had been free and clear. It only takes a couple minutes before all the individuals are gliding away into the open lagoon, to return to their usual haunts. I always like seeing the lemons unassumedly reassuming their place in the lagoon. They gracefully radiate out from the opening in the pen and dissappear into the green waters. With their departure, we leave them to fare for themselves in the lagoon, and have nature run its course. Some of them will not survive, but others we will meet again next year when we census them again.

Lemons swimming to freedom

PIT 2007 has ended. To see some of this year's data and results of our lemon shark census project - Click Here.