Sharkland
Sharkland with net and holding pen locations |
June 16, 2008
Crew sets the longline to catch larger sharks
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Today is the last day of rest before we resume our fishing schedule and look to tackle the second part of the lagoon, an area we call Sharkland. Sharkland is located just south of the North Sound, and is located off of the main lagoon, making it less sheltered than the North Sound. Bigger sharks roam these waters and subadults cruise the flats on the higher tides. This creates a dangerous habitat for the juvenile sharks, as they could fall prey to sopme of their larger bretheren. However, the situation also presents a logical step in research on the life history of lemon sharks. One of our principal investigators, Steve Kessel, is working on the analysis of longline catches over spatial and temporal scales. We look to catch some of these larger sharks (along with several other species, including tiger, blacktip, nurse, caribbean reef, bull, and even hammerhead sharks) via a technique known as long-lining.
Tossing the baited hook and gangion overboard
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The technique is a modification of methods employed by commercial fishermen. A lengthy line is anchored at two ends to the bottom. Along its length are a series of two end floats and fourteen large floats. Between each of these large floats a gangion is clipped onto the line. A gangion consists of a large circle hook on a cable leader with a small float, and rope line to the clip. The idea is to have the shark take the bait and get hooked, but survive the capture by allowing it to drag the clipped gangion up and down the main line between the large floats. The lines are checked every four hours so the sharks do not have to stay on the lines that long. A boat can drive along the length of the line, and looks for any of the small gangion floats being submerged, which usually indicates having caught a shark.
Tossing a large float overboard
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This is where things get interesting and exciting. Catching a big shark is always a thrill and yet requires the team to take a lot of care to safely work with the animal. The animal has to be brought up to the boat gently and positioned so a team member can grab the tail to place a noose on it. The shark is then tied alongside the boat, via the gangion and the tail noose. The sharks are then Casey tagged (using a Nation Marine Fisheries Service tag), measured, sexed, and looked at for general marks, scars etc. The hook is then removed and the tail noose loosened. The shark is given a gentle push and it dissappears back into the blue. Today we set five lines. Four of the lines go in standard locations to the east of the main lagoon. The last line is called the "wild card" and it is moved around to different locations for every set. Today we set the wild card to the south of the eastern end of South Bimini. This is the first longline set we have completed from our newly acquired Twin Vee
vessel. The boat works great, as it has a wide stable platform and large bow to work from. The numerous buckets of lines, floats, boxes of gangions, and bait, and poles, ropes, and tagging equipment all fit in the boat with ease, still leaving plenty of room to work. The setting crew is experienced and the set goes quickly and smoothly.
Tagging workup on a large nurse shark
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The main key to a good set is to get a rhythm going and work the pattern - float, bait, gangion, repeat. There are a few small wrinkles in the pattern. We put temperature data loggers at both ends and in the middle of each line. Many of the gangions also have hook timers on them. These devices are trigered by the shark pulling on the line (they move a magnet out of place) and start a timer. When the gangion is retrieved, the length of time since it was tripped is displayed and recorded for all shark catches. After setting all the lines, we take a drive by them to check for sharks. Today proves to be a productive day, as we catch two large nurse sharks and a juvenile tiger shark. We work all the sharks up off the side of the Twin Vee and again its wide, platform suits the research well. We can have several people all on the same side of the boat working with the shark and the double hull of the Twin Vee prevents the boat from leaning too far to the weighed side and capsizing. Overall, we were impressed with the new vessel's
performance and look forward to its future use as an important tool for the Sharklab's ongoing projects.
June 17, 2008
Sharkland - Night 1 Text by Joey DiBattista
The boats head out to Sharkland
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You could cut the tension with a knife. Our nets were set and the tagging boat set up in our new location (Sharkland); we waited with baited breath for the sharks to hit. PIT sampling in the North Sound was truly a disappointment; we caught 3 times fewer sharks than ever before, and so we hoped that the remaining six nights would save our campaign. Four hours passed with no news; a fresh film crew chronicling the labs activities were buzzing around all boats and conducting interviews in the interim. Film crews are a large part of our research, in truth we rely on their funds and promotional guile to keep the lab running. We operate on a shoestring budget. This particular team is designing a pitch for a show featuring shark research in general; we were lucky enough that they considered our sampling program, and marine research station as interesting, exciting, and educational. Apparently shark sampling is chic.
Weighing a juvenile lemon shark
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“Tagging boat, tagging boat, come back to Tiger Shark”. The airwaves lit up with excited and frantic yells. Two sharks had just hit one of our three gillnets and our crew of four on Tiger Shark were removing the individuals from the mesh. This, it seems, opened the floodgates, the radio box squawked over and over and over, the tagging boat was struggling just to keep pace with the influx of information. A few hours passed while each net was extracting 2, 3, 4 sharks at a time from their nets. Once the tide began to rise, and the boats had enough water to transport their captures to the tagging boat (and main holding pen); the mass exodus began. Between the hours of 2:00 am and 7:30 am we tagged, measured, and weighed seventy-six sharks, more than double the number from the entire six night fishing in the North Sound. Net 3 alone brought in fifty-seven sharks. In fact, we didn’t see or hear from Joy, one of the staff members on the southern most net; she stayed on the net the whole night in case new sharks hit while their boat was dropping off sharks at the tagging boat. Net 3 is definitely where the action is. We always put out a very experienced team on net 3 to deal with the excessive amount of sharks that inevitably ensnares themselves in that net.
Walking a shark in the lagoon
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When the rush hit, the team was hard pressed but answered the call of the bell in remarkable fashion. It is common for many sharks to hit a net in a short period of time, and things get a bit hectic when they do. We even had some of our tagging crew in the water as well, tending to the few sharks that appeared to be stressed from the netting and tagging procedure. At around 5:00 am a serious lightning storm steamrolled through, which forced us to detach from the main pen and drift for an hour while weathering the front. Being surrounded by a bevy of iron rebar is not the safest place to be when lightning is threatening. In all, it was a very exciting and intense night, and a great start to the Sharkland nursery. The team is breathing a big sigh of relief now that the pen has seventy-six healthy sharks swimming around in it. It looks like our fears will be proved groundless and that Sharkland will produce a normal number of sharks. At the end of the night all were exhausted, but pleased that we were catching sharks once again.
June 18, 2008
Sharkland - Night 2 Text by Joey DiBattista
Storm clouds gathered over Bimini
Photo by J. Rajnohova
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Our intentions were good. We arrived up at the pens all set to fish for sharks once again, but the weather had other plans. When our boat circled the main tagging pen we were faced with three to four foot swells, 25 mph winds, and a heavy downpour which made it difficult to see. The rain felt like tiny daggers boring into my eyes. Our boat was literally getting tossed around, as the relentless forces of Mother Nature rained down upon us. We quickly made the call to return to the lab, and wait out the passing squalls in the safety of the yacht club channel. An hour passed and the weather persisted; Doppler radar showed huge rain bands sprouting off the coast of Florida. It was getting late, and we didn't want to set in such bad weather. We made the decision to call it a night, bring all the gear back to the lab, and try again tomorrow. It felt like we made a hasty retreat at the time; with our tails tucked between our legs, but the weather can be a humbling beast. It was the right decision. We have several extra days scheduled for the PIT fishing for just such a set of circumstances.
Lightening flashes across the sky
Photo by E. Solomon
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When dealing with fieldwork, you always have to account for all contingencies, and weather is probably the biggest one. Our goal is to complete the work and get scientific data. However, the safety of the team members is paramount and supercedes getting our fishing effort done. If there is lightening in the vicinity then the set is usually called and the boats return home. The toughest call in the field is whether or not to pull nets or ride a storm out. In these cases we choose to err on the side of caution and bring everyone safely back home to fish another night. So we pull everyone back home, let them dry off, and will look to try Sharkland Night 2 again tomorrow.
Wet clothes were all we got tonight Photo by E. Solomon
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June 19, 2008
Sharkland - Night 2 "Take 2"
A gillnet in the still of dawn
Photo by J. Rajnohova
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We woke up after a good night of sleep and looked to try our luck at setting the gillnets. The weather improved over the last few hours, and clear skies painted the horizon; we were able to set our nets once again. So we paccked up asll our gear and headed out for Sharkland Night Two - Take Two. The night started off much like the first one in Sharkland – a serious lull before the action started. The rush of sharks was much smaller than the first night, but still respectable. The team was spurred to action, removing the juveniles from the nets at a constant pace. The hum of outboard motors could be heard across the lagoon as the boat captains transferred their wards to the main pen and tagging boat.
Lemons cruise in their new home
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The weather seemed to threaten again, as we could see the flashes on lightening in the distance, but mother nature saw fit to allow us to get a full night's work in. The storms swirled around the island but never made a pass overhead. The early hours of the night crept by slowly as most of the action had already passed. We managed to catch a few more stragglers just before dawn and that helped bump our total up
over twenty sharks for the night. So far, so good, as Sharkland 2008 was shaping up to the normal levels of shark catches that we usually observe. The team was starting to relax, as the sharks were coming in and we had the bulk of the catches out of the way. The success of the first two nights of Sharkland have basically made this years PIT Census. The fact that we caught twice as many sharks in the first night of Sharkland as we had in six nights in the North Sound illustrates how poor the catch for the upper lagoon was. It will be interesting to see what happens during next year's PIT census, as the low catch may just be a freak anomoly or we may see a correspondingly bonanza year next year to balance out this year's low numbers.
Moving desal water with the human chain
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We managed to catch a total of twenty-one sharks during the course of the night. The catches included eight newborn sharks, nine recaptured and previously tagged sharks, and four non-newborn but untagged sharks. We seem to catch more untagged sharks in Sharkland than in the North Sound, as the sharks here in the southern part of the lagoon may spend lots of time in the labyrinth of channels and small lakes that run thrroughout the mangroves of East Bimini. Night Two, Take Two
of Sharkland worked out a lot better than the first try, and we now have eighty-seven sharks happily navigating our holding pen.
June 20, 2008
Sharkland - Night 3 Text by Allie Keller
The Sharklab burrito production line
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We were graced with yet another beautiful night here at Sharkland for our third round of fishing. It may have been a little buggy for comfort, but we made it to the haul without a drop of rain (despite the ominous lightning storm looming to the East). As the majority of the sharks are historically caught on the first two nights of fishing, all of us on the tagging boat were expecting a relatively slow, restful evening—and came well prepared with books and fully charged ipods. However, it wasn’t long before the net-boaters, exhausted from the previous nights’ work, began radioing in reservations to the “holiday inn” (the more common name for our beloved “tagging boat”). Hence, the massive game of musical boats began: and most everyone managed to get in some well-deserved rest aboard the floating 2-star hotel.
Making hot chocolate for the away team
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As for myself, I landed aboard Reef Shark (Net boat 2) for the majority of the night—and found myself in good company with Captain Mark Bond behind the tiller and Jana wielding the Q-Beam. Though we initially found ourselves slightly bored without any sharks to speak of, we found solace in a lively game of ipod roulette (of which Jana lost, and now must perform a forfeit that will not be disclosed on the internet). However, as the night progressed, we began to get frequent visits from a curious sub-adult nurse shark—and finally caught our own little Lemon at daybreak. Only minutes later, Net 3 radioed in that they too had caught a shark in those last minutes before haul—bringing the final “score” for the night to a collective total of eight shark: three of which were recaps, and one of which was a neonate.
Serving dinner to the away team on the "Food Run"
Photo by E. Solomon
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Finally, it was time to haul the nets—but not before Tristan had a chance to feed our pen full of hungry elasmobranchs. Jim and myself were lucky enough to snorkel the pen while Tristan baited the water, and we both got some great video footage of the feeding frenzy (especially Jim, who had some close encounters with one particularly curious juvenile). There’s truly no better way to start the morning (or end your day, as the case may be) than swimming around with one hundred-plus hungry lemon sharks.
Weather depending, we may or may not have a rest day tomorrow before our fourth night of fishing. In any case, I’m excited to see what these next three days hold for Sharkland!
June 21, 2008
Sharkland - Night 4 Text by Joey DiBattista
Executing a stomach eversion
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A small team went up to the main pens during the day to complete stomach eversions on a few sharks. The procedure is fairly simple. We catch the shark via a dipnet and bring it over to a boat where we have a padded box filled with water. The shark goes into the box and an anesthetic is added. The shark is monitored until it is observed to go to sleep. The shark is then held upside-down at a forty-five degree angle over a plastic trough. Its mouth is held open and a long pair of thongs is gently slid down its throat all the way to the stomach. With a careful pinch, some of the stomach wall is held and the stomach slowly retracted and teased until it comes out the mouth - sort of like a sock pulled inside out. Whatever was in the sharks stomach will fall neatly into the trough and can be identified later. The shark is then held vertically with its head up and its stomach is gently pushed back down into place. The last step is to take a bilge pump and blow oxygenated water over the sharks gills to revive it. Once the shark is awake again, it can be released into the main pen and its swimming patterns monitored. As an extra measure we look to feed the sharks in the main pen so that the sharks who wake up with empty bellies have a chance to feed. This methodology take advantage of the shark's biology, as in the wild the sharks actually spit their stomachs inside out to get rid of shells, bones, or other hard and tough to digest parts of their prey. In most traditional dietary studies, fish need to be killed and their stomach cut open to see what they ate. The eversion technique is much less invasive and allows us to sample their diet and let them swim away afterwards.
Shark recovery after a stomach eversion
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Usually, we have a day off between the first three nights and the last three nights of fishing in each lagoon area. However, since the weather prevented us from completing night two on our first attempt, we fished last night on our scheduled day of rest. We made the decision to skip a rest day and simply fish on through the next three nights to end up finishing according to schedule. Once again crews were switched; night becomes day and day becomes night for different individuals. Given all this, it can be difficult to get into a proper sleep routine. The shift changes figuratively jolt your circadian rhythm. Everyone settles on a method to cope in the end though - some people powernap to alleviate the fatigue, others are certifiable energizer bunnies and raring to go at all hours of the day or night.
A lemon shark bites some bait
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The nets were set in the same location as nights previous; thankfully we were rewarded with 6 new shark captures, and a couple of neonates to boot. It was a beautiful night as well, and so bugs, wind, and rain were not an issue. We also had one of the home crew volunteers, Chris, treat us to a short (and quite visual) cabaret show set to the music “Lady in Red” by Chris Deburg. He dressed up as a woman of his own volition, and seemed to enjoy it a fair bit ( maybe little too much). He was also the manliest female I’ve ever laid eyes on, and I would hate to meet him in a dank, dark alley somewhere. I shudder at the thought. Thus the time-honored lab tradition of the "drag food run" was kept alive. It is a small and silly touch, but the laughs provided go a long way to keeping morale at peak pitch during the hectic schedule of PIT. We have caught one-hundred and eleven sharks so far with two nights to go.
June 22, 2008
Sharkland - Night 5 Text by Joey DiBattista
A monster bait-cutting session
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Night five of Sharkland and Mother Nature paid us a visit again tonight. Apparently she had a bad day because she was pretty angry. All was calm for an hour or two until an enormous mass of thunderheads rolled in from all directions. We quickly detached the boat from the main pen to avoid being strapped to iron rebar in the middle of an electrical storm. The rains quickly intensified and lightning lit up the night. It was a large, slow moving storm, and so it sat right on top of us for what seemed like ages. Thunder and lightening merged as one, multiple strikes crackled onto land only a few hundred meters away. But after the fury came calm, and after all the rain bands passed we were left with a still and pleasant evening.
A lemon shark gets curious
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During the lulls we entertained ourselves by feeding the sharks in the pen. We put some strips of barracuda on lines and tossed them in to the pen. It took a while for the juvenile lemons to discover that they had nothing to fear from the lines. Once one shark figured it out and grabbed the prize, it did not take long for the others to follow suit. Pretty soon we were watching about a half dozen sharks zoom in and thrash every time a strung bait hit the water. They learn quickly and associate the loud splash with the free meal and come running.
Repairing a gillnet takes skill
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We did manage to get some action tonight though, more even than the previous night. There must have been some sharks "hiding" out from us up in some of the creeks and channels that honeycomb through the mangroves of East Bimini. The nets produced a total of ten sharks through the course of the set. Half of these sharks were newborns, with an additional three being previously captured tagged individuals. Most of the sharks came in a mini rush just after dinnertime. The total shark catches for Sharkland now stands at a very respectable one-hundred and twenty-one individuals and means that this area of the lagoon is exhibiting a normal amount of sharks. We hope to add a couple more, though we have only one night of fishing left. Everyone is excited by the prospect of completing this year's lemon shark census. We head off to bed with one thought in our heads - the last round is coming up and we want to be ready to answer the bell and come out swinging for the last round of PIT 2008. Strap on your seltbelts for Night Six of Sharkland...
June 23, 2008
Sharkland - Night 6 Text by Joey DiBattista
Preparing chicken for dinner
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It is our final night now, and I still can’t believe it’s almost over. Through all the trials and tribulations we managed to catch over 120 sharks in Sharkland. Right on par with previous years, which is quite encouraging. Therefore the North Sound appears to be the one area where sharks, neonates in particular, are lacking. This is troubling; a drastic drop in population size (i.e., bottleneck) has many adverse ecological and genetic side effects. In this case, a decrease in newborns implies a decrease in the number of reproductively active females that utilize the lagoon for parturition; recruitment is down. Next years PIT sampling will be pivotal in ascertaining whether this is truly an anomalous finding or a general pattern for many years to come.
A fine set of freshly baked bread loaves
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Since it is the last night, we only sent out a bare minimum crew, so that we could have a large home team, and plenty of people awake and around tomorrow to give a hand with the PIT wrap-up activities. On this night we caught a few larger lemon sharks, which are always good fun to deal with. One in particular was 112 cm in length, and Steve “The Pink Pidgeon” Kessel boarded the tagging boat to handle the sizeable beast. The shark was well behaved for the most part, aside from the occasional tail thrashing that sent our collection of syringes and scalpel blades flying. I also got in touch with my feminine side on this evening. As part of a lost bet (don’t ask!!!), I was forced to wear skimpy woman’s clothing during mealtime in the field, much to the amusement of the giggling volunteers. I will admit I made an attractive (yet hairy) woman, but the tiny T-shirt and skirt came off soon after the cold winds picked up and whipped through the lagoon.
Cleaning the gear in the AM
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For the last night we managed a respectable six more sharks. This included two previously tagged recaptures and one more newborn. The final catch total for the Sharkland area of the Bimini lagoon was one-hundred and twenty-seven juvenile lemon sharks. The team spent a little time dismantling the small net pens, but soon made their triumphant return to the lab. The
away team went to bed very tired but satisfied in the fact that they had completed the task assigned them. For all the boat captains, who were out all twelve nights of fishing, they could now get a real rest and begin to enjoy the realization of their toil in the field. Everyone deserves a hearty pat on the back for coming together and delivering a great team effort. But before all the praise is doled out and we get too comfortable, many things still need to be done. All the gear has to be cleaned thoroughly, the nets mended, and pens dismantled and the materials returned to the lab. We will spend the next two days conducting clean-up, assessment, repair, and recovery to ensure that we can transition the lab back to its role in facilitating the research projects currently underway. The dizzying pace of PIT will be replaced by a settling back into the tempo of the island. Some friends will leave, while new volunteers will arrive and the lab will return to its customary schedule until PIT rolls around next year...
June 24, 2008
Sharkland - Aftermath Day 1
Repairing Q-beam lights
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Today is the first day of work to conclude the PIT effort. We need to check and clean all the equipment we have used in the last few weeks and put everything away in its proper place. Over the course of the long nights on the boats some equipment can be damaged. Once the fishing is completed, we can make an assessment of any equipment that needs repairing. A particular item that always finds its way into the "repair" pile is the Q-beams. These are very powerful lights that work on the 12-volt boat batteries, and which we use to check the nets and observe sharks in the pen during the dark of the night. While their construction is relatively simple, they are prove to many problems. The most common is that the bulbs burn out (they produce great amounts of light, and therefore heat). Another common problem is that due to the the cords being connected to the heavy boat batteries a simple tug can rip wires or break connectors. All the metal tools are cleaned with fresh water and wiped with an anti-rust protectant. Every tool kit, equipment box, etc. are completely emptied, inventoried, and thoroughly cleaned. The work is time consuming, but highly important, as the maintenence of our equipment prolongs its working life, and ensures that a specific piece of equipment works at the crucial point when it is needed.
Watering plants in the garden
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Since the schedule is pretty chaotic during PIT, many simple tasks around the lab may get pushed on the back burner. With the end of fishing, some of these previously low priorities can be addressed. A good example is the yard and garden. The porch area needs to be straightened up badly. The army of shoes, snorkel gear, and dry boxes are sorted and organized. The garden is tended to and all the plants watered. Everything in the storage sheds are systematically removed, perused, and replaced neatly. The lab is starting to shape up and look smart now. Inside the lab, water jugs and thermoses are cleaned, dried, and put away in the cabinets. The actual lab room
needed to be looked over with a fine pick comb. The lab cabinets and the science cabinet in the hall were torn open and all the equipment from the gear boxes were combined and stored within their marked places in the cabinets. Doc set the lab up to work like a land-based research vessel. There are labels everywhere and every single tool, book, or other object has its own specific place of rest. This aids greatly when you need something, as you know immediately where to look to get it. At first it is a little overwhelming, but once you know the lay of the lab so to speak, you are good to go.
Shark catch data entry
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June 25, 2008
Sharkland - Aftermath Day 2, THE END
The main pen in Sharkland - full of lemons
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Today marks the official end of PIT. We have a special event planned that will involve the entire PIT 2008 Census Crew. A flotilla of boats, carrying the whole group, will make their way up to the main pen in Sharkland. We will feed the sharks, allow everyone to get in the pen and swim with the sharks, and then release the sharks. After the release, we will dismantle the main pen and shuttle all the materials (which includes cinder blocks, rebar, and pen mesh) back to the south island to be brought by truck back to the lab. The release of the sharks is the ceremonial end of PIT and the removal of the pens from the lagoon is the practical end of the census effort.
Everyone snorkeling with the juvenile lemons
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A couple people get into the pen with video cameras and we start to hurl bait into the pen. The lemons are now fully trained and sprint from every corner of the pen at the first splash of bait. The water becomes a boiling mass of small shark fins and bodies where the bait was landing. There was a lot of bait prepared, but it took a surprisingly short time before it was spent. The sharks had full bellies and were looking quite content, so we all decided the time was ripe to get in the pen and give them a closer look before letting them go. The trick is to try and not touch the sandy bottom too much, as the soft sediment easily becomes suspended in the water column and obscures underwater visibility. Too much silt can ruin pictures or video taken in the pen, and these last moments with the sharks in the pen are usually a PIT participant's favorite take-home treasure.
Taking down the main pen
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We allow everyone about twenty minutes to see and photograph the sharks, and then open the door of the pen wide to let them go. Only a few of the sharks discover the road to freedom right away. The deconstruction of the pen begins. After the doorway, we move in one direction around the oval pen. First, the cinder blocks are removed from the bottom mesh and loaded onto the boats. We cut the mesh away from the rebar skeleton with snips. Next, The rebars are pulled out of the sediment and staked in a large group by the mountain of extra cinder blocks that we could not get onto the boats (who have left for their first delivery run to the South Island). Finally, the mesh is pulled out straight and then tighly rolled up. As the pen comes down, an opening gapes larger and larger, and the sharks find their way out and disperse in disparate directions according to their own whims. With the return of the sharks to the lagoon and their everyday lives, PIT 2008 is officially at a close. We have worked hard, had fun, and added information to our understanding of the life history of the lemon shark. All that is left to do is to enjoy our celebratory dinner tomorrow night. A hearty "Great Job" to everyone on the PIT 2008 Lemon Shark Census Project Crew.
Rolling up the pen mesh
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