Chagos 2016 - Day 4

Scientists from TRCC and GTOPP are at sea in the Indian Ocean with the Bertarelli Foundation's Chagos Archipelago Science Expedition 2016.  Dr Heather Koldewey, Chief Scientist of the Expedition, wrote: 

Day 4 highlights – 8th April 2016, Peros Banhos 

Turtle Team

• Today saw one turtle track on Vache Marine

• Aerial surveys completed in southwest of Peros Banhos atoll

• Signs (bottom) that the donkey is alive and well!

• Thanks Benoit and Lukas for continuing the turtle (and donkey!) research!

Coral Reef Team

• A busy day of surveys inside the lagoon (Bernards Knoll) and on the seaward side of Ile Poule.
• Ile Poule site had abundant reef fish populations.

Coral Health - Peros Banhos Reflection
• Past 3 days surveyed north, west & south
– Reef seems healthier in southern Peros Banhos
• But here at critical time
– Southern Peros Banhos sites showing early signs of bleaching

• –  Very worrying as large amount of damage to coral likely
  
• –  However, large numbers of juvenile corals on reef that appear less affected – so potential good recovery
  
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Lagoonal twilight zone reefs

• Continued twilight reef exploration (deeper than 30m) with the ROV in Peros Banhos lagoon:

• –  Interesting mix of corals and large fleshy algae not seen on shallow reefs
  
• –  3 grey & 1 black-tip reef sharks hanging out under VAVA II
  
• –  ‘Flattened’ corals adapted to deep reefs
  

Tagging and Array team

All hydrophones (except one which will be done early tomorrow) in Peros Banhos serviced

Great achievement by the Array Team and a huge amount of work!

Tagging team
• An exciting and very busy day for the tagging team:

• –  13 sharks tagged (grey reef sharks and silvertips)
  
• –  First camera tag deployed on grey reef shark
  
• –  First new generation tag deployed on grey reef shark
  

New Generation Pop Up Satellite Tag on Grey Reef Shark

A stunning end to another busy and productive day. Thanks everyone! 

Chagos 2016 - Day 3

Scientists from TRCC and GTOPP are at sea in the Indian Ocean with the Bertarelli Foundation's Chagos Archipelago Science Expedition 2016.  Dr Heather Koldewey, Chief Scientist of the Expedition, wrote: 

Day 3 highlights – 7th April 2016 , Peros Banhos

Turtle Team

• Today saw two good hawksbill turtle tracks:
  
• One at Ile Diamant
• One at Ile Yéyé (picture). This track was extremely fresh – either from last night or early morning
• Thanks Benoit and Lukas for continuing the turtle research! 
  

Coral Reef Team

• A busy day of surveys around Petit Coquillage in Peros Banhos and we enjoyed a turtle inspection and seeing reef and nurse sharks during the dives.
  
• Limited bleaching at present–only in occasional colonies. Water temperature is currently warm at 30- 31 degrees C.

Monitoring the reef ecosystem

• A newly designed automatic water sampler was deployed that collects water every 2 hours over a 24 hour period.
  
• The collected water will be sent back to Stanford University to precisely measure different forms of carbon.
  
• We will then quantify the calcification to net photosynthesis ratio to monitor ecosystem function.
  

Tagging & Array Team

• The array team continued to recover and redeploy receivers in the array, servicing 10 receivers and expanding our array at Speakers Bank.
  
• The expansion of the array at Speakers Bank included the first deployments of acoustic receivers set on acoustic releases, expanding our ability to monitor deep water habitats.

A nurse shark inspects a receiver

• The tagging team tagged one grey reef shark and caught and sampled a variety of pelagic fishes at Speakers Bank.
  
• The surprising abundance of pelagic fish at Speakers Bank led Dr Barbara Block to refer to it as a “tuna hotel”. 
  

Robbie with a yellowfin tuna at Speakers Bank. This fish was released. 

Thanks to all on Vava II, especially the Captain and crew, for a fantastic and productive day! 

Tag-A-Giant Nova Scotia 2015: First Bite

It’s 6am and the floodlights cast their rays on the back deck of the f/v Bay Queen IV in Murphy’s Pond, Port Hood’s small commercial fishing port on the west coast of Cape Breton Island, Nova Scotia.  Captain Dennis Cameron and mate Lloyd MacInnes move around the deck coiling lines and crimping monofilament, bantering over the low rumble of the inboard.

Murphy's Pond in Port Hood, Nova Scotia 
photo credit: R. Schallert

We approach the dock in our minivan loaded with crates of scientific gear and snacks for our day on the water. Dr. Steve Wilson and Robbie Schallert of Stanford University and the Tag-A-Giant Foundation lift a heavy silver crate and shuffle towards the Bay Queen IV, greeting the crews of the various vessels staging their gear in the grey light.  The crate is full of acoustic and satellite tags that, with luck, will be deployed on some of the largest tunas in the world.

The TAG team has been coming up to Nova Scotia every fall for the past 8 years and it shows.  Robbie cracks jokes with Melvin, Troy, Carl and more as we make our way down the floating dock. TAG has fostered lifelong relationships within the Port Hood community to create a collaborative environment; we couldn’t tag without their ocean expertise, and our research contributes to the sustainable management of their local bluefin fishery.

Loading the bait well with mackerel in the morning light
photo credit: E. Estess 

We shove off as the clouds turn a light pink hue. The first order of business, as with all fishing, is bait.  Dennis eyes the echo sounder and quickly shifts out of gear when he spots a school of mackerel.  We keep the biggest mackerel in the live-well and motor off towards the tuna grounds.  Once we’re in the zone Lloyd rigs up two of the thick rods with live mackerel and pink balloons as surface floats, and the third rod is connected to a kite line to dangle a live mackerel at the surface.  And now we wait.

Radio calls come in from across the Gulf of St. Lawrence.  “Congratulations Bill, glad to hear you got your fish.”  “We’re marking lots of fish over here boys.”  Again, I take note of the friendly, collaborative nature of the fishery. Canadians really are as nice as people say!  After hours of silence we decide to pick up our lines and try another spot. More silence and no tuna marks on the echo sounder.

Searching the Gulf of St. Lawrence for giant bluefin
photo credit: R. Schallert

This is our second day on the water and the fishing has been silent.  Not to mention the weather has been on the rough side of the spectrum.  Part of me accepts that this is the nature of fishing- the bite is always hotter the week before. It’s fishing, not catching. Am I wearing my lucky tuna belt? I didn’t even bring any bananas on board.  These old catchphrases and superstitions drift through my mind as the hours flow on.

Deep down I know I’m paying a karmic penance after my last trip up to Port Hood in 2013, when we tagged up to 9 giant bluefin in a day and fished for 5 days straight in sunny, flat calm conditions.  I knew I was going to have to pay some dues, and bouncing around in the cabin with my hands shoved deep into my foul weather jacket to keep warm in the Arctic breeze, I accepted my fate with a meditative mantra, “It’s fishing, not tagging.”

Wind on the water. Waiting for action.
photo credit: E. Estess

At that moment, I watched the monofilament pull tight and the pink balloon float disappear. SNAP! The rubber band holding the Teflon leader guard broke and it rocketed down the line to protect the mono leader from the glass-sharp teeth of the giant tuna below.  BZZZZZZZZZZZ the line screamed off the reel as Lloyd rocketed across the deck and started cranking away.  Dennis began maneuvering the vessel, backing down on the fish to gain slack in the 300lb test line like a boxer circling their opponent in the ring.  The rod bent with strain as the fish made a run and Lloyd waited patiently for his chance to gain line.

  

But as quickly as it had come, the tuna jerked the hook from its mouth and was gone.  Lloyd silently reeled in the slack line, pausing to look at the bent hook.  Strike one, but after days of no action the reminder of the power of these animals was enough inspiration.  The fish are around. They’re always on the move throughout the gulf waters as they hunt for herring and mackerel, and it takes skill and decent dose of luck to line up on them.  Weather permitting, we will be putting in our time these next weeks to tag and release these beautiful giants, unlocking the secrets of their life history and migratory routes to inform the sustainable management of the tuna fishery.

Hoping for an evening bite.
photo credit: E. Estess

Bluefin Satellite Tag Hunt

Low Fog kisses the Highlands along the Cabot Trail

Place yourself for a moment in the office of a tuna tagging scientist staring at a map with a GPS location of a popped-off mini-PAT satellite tag.  The tag had been attached to a Giant Bluefin Tuna for the past 10 months, and it contains a virtual diary of its movements, behaviours and environments encountered.  The tag is sending a summary of the tuna’s story to a satellite which relays it to your computer.  This summary data is like reading the first and final chapter of a novel and the story line on the back cover.  It’s valuable and you get the highlights and main point of it all, but you feel cheated somehow, especially after you spent weeks travelling and fishing to tag the tuna in the first place. If you can get the tag back, you can download the entire "story".

A lot of tags pop off far from shore, well beyond reach of an inshore vessel’s range.  So what happens when a tag comes to the surface 15 kms from shore?  And 25 kms from the nearest port where you know a local fisher who has a boat at the dock?  You scramble; you email, call and coordinate a recovery as fast as humanly possible…and then you pray, for good weather, calm seas and good visibility.  On Wednesday, this week, such an event happened.  Although I wasn’t the scientist staring at the map of the first GPS location, early Thursday morning...I was the scientist along with a Honours student from Acadia University rushing to the dock to jump on board the ‘Mary Heather’ captained by TAG-A-GIANT’s Captain Lloyd MacInnes based out of Little River, Cape Breton, Nova Scotia.

The search for the tag begins

Finding a tag the size of an egg with a thin black antenna sticking out would be an ok Easter-egg-hunt on land. However, throw in waves, a large area, a GPS location that is hours old, and the fact that the tag is floating with only the antenna peaking out, all of a sudden the easter egg hunt isn't quite as easy. That’s where Seth Newall, a Honours student from Acadia University comes in.  He brought a "tag locator" with him, which picks up the specific frequency of the tag and allows us to home in on the signal.  It’s a lot like playing ‘hot-cold’ as a kid, except you’re still looking for a black, half-submerged tag within 300 to 50 m of the boat.  So with Captain Lloyd at the helm spinning circles and squiggles on his chart display, Seth relaying signal strength of the tag, and myself standing on the cabin roof searching the water, we played that very game.  It was bit foggy, but relatively calm, no breaking waves or chop.  With help texts coming from TAG-A-GIANT’s Robbie Schallert in Texas, we honed our rookie skills using the tag locator.  Seth’s signal strength got stronger as the search continued.  After 3 hours of playing hide-and-seek, I spotted the black egg with antenna sticking straight up, 20 m off the port bow.

“I got it!” I yelled out, “10 o’clock! 60 feet off the port side!”

“I see it!” confirmed Captain Lloyd.

“Seth, grab the dip net while I keep an eye on it!” I instructed.

Captain Lloyd had the boat alongside the tag within seconds.  He wasn’t waiting for a dip net.  He had a deck-brush in hand and was frantically sweeping the tag closer to the boat.  Seth netted our find and with that, we had in hand the day-to-day story of one Bluefin.

Relieved Capt. with the tag

Close up of the Wildlife Computers miniPAT

Steaming back to port, the sun broke through the fog to illuminate the sea’s surface and rocky cliffs onshore, yet the lush green mountain tops of Cape Breton’s Highlands remained covered.  A pod of white-sided dolphins broke the surface and a puffin dove under upon the Mary Heather’s approach.  Some gifts in view while others remained out of sight, a fitting summary to our search’s conclusion.

Acadia Team with the tag safely secured!!

-          Written by Aaron Spares, Acadia University Coastal Ecology Lab 

Chagos 3.0 - Day 10: Last-Minute Mantas

After 10 busy days we are reluctantly leaving Chagos, heading to Blenheim Reef and Speaker’s Bank in the north-west on our way out of the archipelago. It’s an early start for our last day. At 4:30am I’m filling tanks, and we already have one of our final round of receiver deployments out of the way before the sun rises. Chagos treats us to one last spectacular sunrise: an orange ball floats above Ile de Passe at Salomon Atoll as we drift at the lagoon entrance while our dive team deploy the temperature and dissolved oxygen loggers used to monitor water conditions around our acoustic receiver network.

As we prepare to leave Salomon we have one last surprise. Manta rays are feeding at the surface around the boat, and eagle-eyed captain guides the tender into position allowing us to get one last satellite tag attached. Every piece of data counts, and this tag will be a valuable addition to the information this expedition can provide.

This has been a fantastic trip, and yet again the teamwork between our group of six scientists (and diving doctor) and the ship’s crew has been the key to its success. The Chagos acoustic array now comprises 63 acoustic receivers, and we have tagged over 160 animals since the project’s start in 2013. Our two VR4 Globals have been successfully repaired and we have two of last year’s sharks already ‘talking’ to us as they swim by.



As we leave Speaker’s Bank, we say goodbye to Chagos for another year.

Chagos 3.0 - Day 9: Chagos Goes Global

Deploying the latest technology in the field can be fraught with difficulties, and our Vemco VR4 Global receivers are certainly high tech. Not only do they detect and record shark movements, but they are equipped with an Iridium satellite antenna, mounted on a surface buoy, that sends information about detections straight back to us in real time, allowing us to monitor our sharks from anywhere in the world.

A Vemco VR4 Global buoy floats at the surface, uplinking
to Iridium satellites through the dome at the top.

Ensuring that each step in the chain, from detection to sending the signal to the surface unit to transmitting the signal to the satellite, is working perfectly requires patience and a lot of testing – after all it will be twelve months before we have a chance to service this equipment again.

Dr Taylor Chapple is our team’s expert on working with the ‘Globals’, and he has had a busy couple of days. Despite having no apparent issues with replacing batteries, cleaning, and reinstalling both our units earlier in the expedition, we had been getting no data sent through, despite everything apparently working perfectly. Taylor, supported remotely by the Vemco team, worked to eliminate all the possible causes by testing each link in the chain. He concluded that it might be the hydrophone – the listening tip of the system – or its connection that was causing the problems.

With spare hydrophones carefully swaddled in bubble-wrap we set out to our the first of our Global receivers again, this time with a battery of additional testing equipment. Two divers detached the hydrophone from the mooring cable and passed it up to Taylor, who carefully changed the hydrophone and checked the connections, before placing it back in the water with some test transmitters. Connecting wirelessly to the surface part of the system, he is able to see what the system sees, and he was quickly able to confirm that it was now detecting the tags. Hot on the heels of this a radio call from Robbie Schallert, back on board the ship, confirmed that the system was also sending the data back to Vemco. We were back on line! Carefully reattaching the hydrophone back to its anchor, the system was ready to go for another year of work in Chagos.

Dealing with problems like this in the field requires patience and resourcefulness, and the support of a good team at home as well!

Chagos 3.0 - Day 7: Chasing Giants

Today finds us at the Egmont Islands, off the south west corner of the Great Chagos Bank. We've come here looking for manta rays, which we know from previous visits to be a common sight around the reefs and within the lagoon. The purpose of our visit here is to acoustically tag some of the manta population and deploy some of our acoustic receivers to track their movements over the coming year. The aim is to understand how resident the mantas of Egmont are, and the influence of the tides and other natural cycles on their daily movements around this small atoll.

Firstly, however, you need to find a manta, and this year we have a new tool at our disposal – a Phantom camera drone. Able to relay live images from a bird eye view to the pilot on the deck of the boat, we can locate groups of mantas and direct the tagging team to the area.

The Phantom camera drone is on the lookout!

Tagging mantas is a somewhat different exercise to the work with sharks – rather than fishing for them (it is too hard to get plankton on a hook) we have to search for mantas feeding near the surface and then apply the tags directly, either from the boat or by free-diving alongside them. A calm approach is needed, both to avoid spooking the animals and sending them to deeper water.

The day proved to be rich in mantas, with 12 tags going out and then a reef dive in the afternoon encountering at least eight more feeding at depth along the entrance to the lagoon. The shark work continued in between manta sorties, and we acoustically tagged a further 11 animals, including our largest reef shark of the trip so far – an impressive male silvertip measuring almost two metres. With three days left here we are making good progress.

Taylor attempts to tag a manta

Aside from the science workload, our most senior scientist and the trip’s doctor have been moonlighting in the galley, producing excellent desserts to complement the already abundant meals aboard. Hopefully all the hard work on deck will keep waistlines in check!

   -Dave Tickler