Wednesday, July 6, 2016

Top of the Tagging Pacific Bluefin Tuna Learning Curve!

Barb and Robbie tagging a Pacific bluefin
The trip aboard the shogun reached new territory today as the team aboard hit historic high levels of excitement as we finally had the banner day we were working towards. Five times today we had explosive bites while Kite fishing on breezing schools of the largest Pacific  bluefin we have ever seen in the eastern Pacific. Captain Aaron and Angler Chalie Morito along with crew member Tyler and several others worked seamlessly as a team sighting school after school of large almost giant bluefin feeding at the surface. After hookup long fights pursued in heavy tackle culminating at the swim step where the Tag team took over and gracefully captured each fish in slings barely large enough to hold the fish. Four men lifted the fish to four on deck tackling over 300 lbs of lift. The TAG team handled the fish like in a pit stop- each fish came came into the tagging station and were double tagged then sent on their way. Fish were feeding on Red crabs and anchovy. The fish had DNA and RNA samples taken and swam away strong. Five fish over six hours were  tagged and he team felt a sense of accomplishment as the techniques worked out early in the week succeeded with enormous efficiency and success. By the end of the day all ten satellite tags aboard were out in the sea on the largest Pacific bluefin the team has ever tagged in the North Pacific.  This is terrific for our efforts to learn the exact timing of when the fish spawn. 


A large bluefin being double-tagged on the Shogun  deck

Tuesday, July 5, 2016

Archival Tagging Bluefin in Mexico!

The focus turned from tagging large bluefin with satellite tags
in  US waters to getting out surgically implanted archival tags in
high numbers today- and to help us achieve our mission- our Mexican
colleagues at Baja Aquafarms  of Ensenada, Mexico- contributed 32
fish ranging from 40 to 70  lb fish for tagging. We came to some tow
pens maintained by the famr early in the AM, that had beautiful f2016
captured fish circling-that had been caught about a month earlier.
The fish were already feeding and looked quite well. To catch the
fish we used lift poles- manned by two of the crew, and with the help
of their divers and some members of our team- we coordinated the
capture of the fish in a sling, the removal of the hook, and the
transfer to the archival tagging station. The entire operation took
less then two hours (30 fish tagged), and was orchestrated from start
to finish with well coordinated steps. Fish were caught on a barbless
hook by Charlie, Aaron and Renne, then moved to a sling manned by Dr.
Daniel Madigan. Dan managed to keep the fish in the sling with some
water along with two divers assisting and passed off the fish to
teammates waiting on deck led by Dr. Luke Garnder. Luke's team
managed to bring the fish to the tagging station and were greeted by
Drs. Dale and Block, and TAG scientist, Mr. Robbie Schallert.
Together this team placed a surgical archival tag in the fish, took a
sample of muscle for mRNA, and DNA samples, and completed the process
in quick succession 30 different times! All fish looked good and what
made the entire team happy- is that just as we pulled away from the
pens- the captain sited more wild fish- and we within the space of an
hour tagged a few more of the same size class in the pen. It was a
glorious moment- to get about 32 tags out- and all on 3-4 year old
fish. These tags will last up to six years in the wild taking high
resolution data. And have the promise of showing how these fish
mature- the ontogenetics of their changing behavior and the route to
the various spawning grounds. Their only fault is that we need to get
the tags back!


Monday, July 4, 2016

The Pacific Bluefin Got Even Bigger!

On Independence Day 2016 the Tag team aboard the Shogun actually made some real history. We have struggled to learn how to capture tag and release the largest Pacific bluefin tuna we have seen in our lifetime and this day proved more successful then the previous two. Today aboard the shogun, a long range recreational fishing boat out of San Diego we were able to catch three Pacific bluefin that taped  twice on two fish to 184 cm (72-73 inch fish) above the 200 lb class of Pacific bluefin and get them to the swim step. Two of the three  fish were in excellent condition for double tagging with pop up satellite archival tags and an implantable archival tag went in surgically in both. The tasks were challenging for the team from the hook up on a kite with a surface bait to the fight on heavy stand up tackle in the open ocean.The coordination and capacity for our team to capture in a sling and lift a large fish and the water draining from the  sling to the deck for tagging. Led by Robbie Schallert of TAG and Dr  Luke Gardner of Stanford the men with help from many others were able to place the large fish in a sling and move it to the deck placed Mats for tagging.   Pacific bluefin older the six years of age hold a secret we want to know: Where and when do they breed in the Pacific. The excitement aboard the Shogun is that this is a challenging operation and we are succeeding and improving daily. Five of these large fish have been hooked  successfully and three to date tagged and one sampled intensively. These fish hold a secret to he life history of bluefin we all seek to understand. This tagging trip working out the techniques to handle large bluefin for this realm reminds me of our work over twenty years ago off North Carolina in 1996 when a small team from the TRCC went out with Captain Bob Eakes to figure out how to tag and release this similar class of fish on the east coast. From the 1996 work we went on to tag 1300 Atlantic bluefin most bigger then the fish we are working on today. Our goal as we go forward is to satellite tag the larger bluefin we can catch in the Pacific but it's very hard to access these large fish. 

But confidence grows from catching three and releasing two large Pacific bluefin on the fourth of July and we are all excited about what we are seeing. The fish are packed full of red tuna crabs and anchovy. More bait and whales and Albatross and shearwaters making a hot spot on tthis region of our blue Serengeti of the California Current. 


Friday, July 1, 2016

Bluefin Tuna Special

Our Pacific bluefin tuna tagging and collecting trip  is out in the Pacific aboard the Shogun a recreational long Range fishing boat we've used annually to do this trip. The objective of the cruise is to electronic tag Pacific bluefin tuna and study their migrations to the spawning grounds in the western Pacific. In addition we hope to collect 15 to 20!bluefin tuna for the TRCC lab to conduct feeding studies.   For tagging we use two types of electronic tags each with their target size of fish and story we hope to tell with the data  One type of electronic tag is a Pop up satellite tag that is programmed to stay on the fish for one year and potentially show us where the largest year classes go after foraging in the eastern Pacific hot spots. This is a hot question in current Pacific bluefin tuna science. The other type of tag is called an archival tag. These tags are programmed to last six years and will provide in depth data in what a bluefin does over the entire period In 10-20 second intervals. That would be immense data and to far we've successfully used these techniques up to three years in the Pacific and five years in the Atlantic. These tags are brand new and when we put them in fish off the shores of North America we hope to see them five to six years from now recaptured. They have the potential to record the daily position, thus the journeys and behavior in high resolution for the entire six years.  They carry three languages  and all say Return for Big reward.bit takes a fisher person to get the tag back. But we know this works to date we have 53 percent returned in the Pacific and about twenty percent in the Atlantic.  It takes a lot of international cooperation but we are hopeful as this type of tagging has given Atlantic and Pacific bluefin tuna researchers the most  detail required to increase our knowledge of when and where tuna spawn a critical question essential to life history and management questions. In addition these tags provide oceanography and behavioral data essential for better understanding the fish. 

Slow Bite but Big Fish😎

Today the first of July l, we got off to great start with the pop up satellite tagging of our first fish which by measurement is the largest fish we ever have tagged on the Shogun. The bluefin tuna was caught by a crew member and measured 177  cm in curved length. We estimate the fish was close to 190-200 lbs. 

We caught the fish using innovative techniques by the Shogun crew and met the challenge of lifting it on board from a swim step and satellite tagging the fish.   If the tag stays on (a problem for these fast moving fish) we hope to get a year of data on where the bluefin tuna go to spawn.  Fish of this size class are very hard to catch as bluefin tuna vision is extraordinary. We were able to catch two more bluefin tuna of a smaller size class well above the size we intend to collect and for our first day we ended with two archival tags and the largest fish ever in twenty years of TRCC tagging. Great start! 

- Barbara Block