Friday, October 4, 2013

TAG Canada 2013: Epic Tagging!
Dr. Steve Wilson and Robbie Schallert tag a giant bluefin
in Port Hood, Nova Scotia

The TAG team is up in Canada where we’ve had an epic 5 days of nonstop bluefin tagging.  I’m Ethan Estess from the Monterey Bay Aquarium and Stanford University’s Tuna Research and Conservation Center, here with TAG scientists Robbie Schallert and Dr. Steve Wilson of Stanford University. We came to Port Hood, Nova Scotia on September 27th to work with Mike Stokesbury's team from Acadia University to study giant bluefin in the Gulf of Saint Lawrence.

TAG team Dr. Steve Wilson, Robbie Schallert (center), and Cpt. Dennis Cameron (at head irrigating the gills)

We awoke on the 28th to flat calm seas and sunny skies. The Tag-A-Giant team headed out with Captain Dennis Cameron and Craig of the Bay Queen IV and Bernie and Steve of the Carrie Anne.  The bait had barely hit the water when we hooked up on a giant bluefin tuna.  An hour later the 270cm fish was on the tagging mat and a minute later it was back out the door, outfitted with an acoustic and pop-up archival tag (PAT).  These tags will help unlock the mysteries of bluefin migratory patterns and spawning cycles, providing critical information for their management and conservation.   To date most of these Canadian giants have been tracked to the Gulf of Mexico spawning grounds, but a few (less then 2%) make their way to the Mediterranean Sea.

A giant bluefin tuna being reeled in by the crew 
of the Bay Queen IV

The bluefin were there in force to feed on the large schools of herring in the region.  We double tagged 6 fish with acoustics and pop-ups, and many of these fish were the largest I had seen.  All of Sunday’s fish were over 260cm, easily weighing 800 pounds or more.  These fish were extremely well fed and very big around!

Measuring the length of a giant bluefin

Over the next 3 days we deployed 14 more electronic tags in perfect fishing conditions.  Cape Breton is one of the most beautiful places I’ve ever been and we were surrounded by spectacular wildlife.  Hundreds of pilot whales, or “blackfish” as our captain called them, circled our boat throughout.  They were there for the same reason the bluefin were- to feed on the massive schools of herring spawning along the island.   Gannets dive-bombed and grey seals bobbed along with curious glances towards our bait.  One of the highlights of the trip was placing a tag in the largest giant bluefin TAG has ever tagged- a 313cm bluefin we tagged and released.  This behemoth barely fit on the deck of the Day Queen IV.  This fish is surely a spawner, and hopefully its PAT tag will teach us about bluefin spawning locations and behaviors in the Gulf of Mexico.

Surrounded by hungry pilot whales with our other fishing vessel
the Carrie Anne in the background

 Cape Breton sunset

Thursday, April 25, 2013

Tunas with Laser Beams!

A yellowfin tuna swims in the flume as an infrared laser beam reveals the flow patterns around its tail (photo B. Block)

A collaborative project between Massachusetts Institute of Technology and the TRCC team has been undertaken to characterize the water flow around live, swimming tunas.  Professor Block and visiting MIT Professor Alexandra Techet and graduate student Leah Mendelson have been leading the charge on this complex and challenging study.  The team is on a mission to better understand the underlying mechanisms that enable these highly streamlined organisms to swim at high speed and migrate across ocean basins.

MIT graduate student Leah Mendelson dawns her laser safety glasses as she captures high speed footage of the swimming tuna (photo B. Block)

Over the past 6 months Postdocs Adrian Gleiss and Jon Dale and graduate student Dane Klinger have trained bluefin and yellowfin tuna to swim steadily in the lab’s respirometer.  This specialized tank generates flow that enables the tuna to swim in place in a sealed acrylic chamber.  The tunas become acclimated to swimming in the environment through subsequent runs in the respirometer, and for this week’s project we’ve selected the calmest, most steady-swimming individuals as brave test pilots for this never-before-attempted study.

High-speed footage of the illuminated particles, seen here flowing over a bluefin tuna’s finlets, will be input into a mathematical model that will reconstruct the fluid motion around these features (video B. Block)

The team is applying a technique called PIV (Particle Imaging Velocimetry) to observe the fluid flow around the body and fins of a swimming tuna.  This technique involves seeding the seawater in the respirometer with small (20 micron) polyamide particles, which when illuminated by an infrared laser beam enable a high-speed camera to track the motion of each individual particle.  Subsequent analysis of this high-speed footage will enable the researchers to construct mathematical models of the particle movement around various features of the fish.  For the first time, we will be able to visualize the fluid flow from the head to tail of a swimming tuna.  Stay tuned to check out the results of this cutting edge project.  

(left-to-right) Graduate student Leah Mendelson, Professor Alexandra Techet, and Professor Barbara Block in front of the TRCC at Hopkins Marine Station (photo E. Estess)

Friday, February 1, 2013

the Chagos Archipelago

The mission to the Chagos Archipelago has begun...we finally arrived in the Maldives after two days of traveling...crossing 13 time zones. The Bertarelli Foundation has joined forces with TRCC/TAG/GTOPP to tag apex predators in one of the most remote and protected reef systems in the world. In 2010, the Chagos became the largest marine protected area in the world at 644,000 square kilometers. We have 65 tags (15 miniPAT and 50 acoustic) to deploy on various species...from tuna to sharks to rays. And a 10 receiver acoustic array to set-up.

This morning we will fly across the equator to meet our hosts aboard the Vava II...the 314 foot ship is docked in Gan Island on the southernmost atoll in the Maldives. From there we head due south 500 kilometers.

-Robbie Schallert

Tuesday, January 8, 2013

Sea Surfing “Wave Glider” to Search for Bluefin Tuna and Striped Bass off the North Carolina Coast

The Wave Glider Carey begins her latest mission

A mobile robot called a Wave Glider outfitted with acoustic receivers to detect free-swimming tagged fish was put in the ocean off the coast of Beaufort, North Carolina today. The glider was launched from the Duke ship R/V Susan Hudson outside the Beaufort Inlet by Drs. Dick Barber and Joe Bonaventura of Duke University.  The Glider is part of a collaborative experiment to test the capacity of the unmanned robot designed for biological ocean observation, to detect where animals are in relationship to ocean conditions. For this first test off the North Carolina seaboard, scientists from Stanford, Duke and Eastern Carolina University are working together to listen for tagged bluefin tuna, striped bass and sturgeon that overwinter in North Carolina waters.

Monitoring marine species is valuable not only for the data about their whereabouts but also to better understand our changing oceans and climate. These species can act as roving reporters providing knowledge of their presence or absence in relationship to ocean conditions.  Bluefins and striped bass overwinter in the coastal waters of North Carolina to feed on Menhaden an oily forage fish that is a coastal favorite of both species.

“I am really enthusiastic about the role of the Wave Glider, this new ocean robot, to help us detect where fish are” said Dr. Barbara Block a professor from Stanford University. “We’ve been tagging bluefin tuna for years, through the Tag-A-Giant program, off the Carolina coast and we’re now moving into the phase of developing techniques to long-term monitor their presence or absence along the eastern Seaboard. The glider provides an opportunity to experiment with how to do this in the rough winter conditions of the Hatteras coastline.”

The Stanford team tags a giant bluefin
The bluefin tunas Block is searching for were tagged with long-term acoustic tags in Canada this past summer and fall. Block estimates there are over 50 bluefin with tags roaming the Atlantic seas, and is hoping that the hot spot region off Carolina will attract the tagged fish into the region. She and her team have studied bluefin tuna for years determined previously this foraging hot spot is like a favorite restaurant where the tunas tend to gather from several populations roaming in the North Atlantic. By deploying the Wave Glider in this region, they hope to hear the tags’ acoustic pings, which allow them to detect and identify individual tunas.

In addition, ECU professor Roger Rulifson is leading a team on the R/V Cape Hatteras, an NSF ship managed by Duke University, which will be out tagging stripped bass acoustic tags.  “We hope that the Glider can pick up some of the new animals we’re releasing in the next few weeks and help monitor the presence of a variety of fish and sharks we’ve been tagging in the region the past few years,” said Rulifson.  Like Barbara, he is investigating how mobile receivers can aid in the teams capacity to monitor where fish are in the rough winter conditions off the Carolina coast.

Duke University Professor Dick Barber stands with the Carey glider
The glider is was deployed by two of Block’s mentors, Drs. Joe Bonaventura and  Dick Barber from Duke University, where Block got her Ph.D. in 1986. “Ocean Observation is critically important, and I am pleased to see the next steps in biological observation being tested here off North Carolina,” says Professor Dick Barber. “I was fortunate to know Frank Carey, the pioneering tuna scientists from Woods Hole Oceanographic, and a Duke Post-doc, after whom the Carey Glider was named, and he would be very pleased to know of the experimental importance of this mission- chasing Atlantic bluefin and striped bass off our coast”. 

The Wave Glider is manufactured by Liquid Robotics of Sunnyvale California. The project is funded by a Rolex award to Block, The Tag A Giant Fund, Duke University, Stanford University and Liquid Robotics.