Sunday, October 26, 2008
catching fleet worked together transferring 6 fish from the boats to the Bay Queen IV. The team worked together where every boat in the TAG Fleet contributed with a fish for transfer and we succeeded tagging 2.5 Tons of fish several measured in the1000 # class. The Tags are set for 240-300 days- We hope to see where these fish go to Breed. Dr. Steve Wilson and Aaron Spares are leading the charge and the picture above shows Dr. Steve tagging a big one. Aaron, Sheldon (near the hose), mate Mike and Captain Pete are helping on the deck. The fishers of Nova Scotia and PEI are doing the hard work of catching and transferring the fish. More quota has been allocated, when its all captured- we'll be back out tagging- Barb for Dr. Wilson Go Steve!
Saturday, October 25, 2008
Canada Hits 1000!
1,000 TAGS REVEAL MYSTERIES OF GIANT BLUEFIN TUNA
A giant Atlantic bluefin tuna weighing more than half a ton had the honor of being fitted with the 1000th electronic tracking tag placed by our team on an Atlantic bluefin when it was caught and released on Monday (October 20) in the Gulf of St. Lawrence off Port Hood, Nova Scotia. The prized fish, which measured 10 feet in length, was tagged by our scientific team from Stanford University, Dalhousie University and the Monterey Bay Aquarium, working in collaboration with Canadian fishermen from Prince Edward Island and Nova Scotia. The field team was led by Drs. Mike Stokesbury of Dalhousie University and Steve Wilson of Stanford University. Mr. Aaron Spares was also on board helping to tag and lip hook the fish. This is the 5th tag deployed this year from our Canadian squad who also succeeded in the past weeks putting out some acoustic and archival tagged giants. The tunas this week are getting only the Pop Up Satellite Archival tag- build by Wildlife Computers who have been large supporters of the TAG effort.
The TAG team has been tagging bluefin tuna since 1996, when the first tag was put out on a bluefin tuna off North Carolina’s Outer Banks. We have traveled from the Gulf of St. Lawrence to the Gulf of Mexico and from Ireland, to Corsica and to Spain to tag Atlantic bluefin tuna. Placing 1,000 tags on giant bluefin has been a long quest for TAG researchers, whose work has helped to reveal the life histories of these amazing, elusive creatures. The tagging data assembled by the TAG researchers have been vital in identifying how populations of bluefin tuna use the North Atlantic, leading to new discoveries about their physiology, their migratory patterns and their population structure.
I would like to thank all those responsible for helping us to achieve the Herculean task of deploying 1,000 electronic tags on giant Atlantic bluefin tuna, with special recognition of our Gulf of St. Lawrence team who realized the goal: the captains and crew of the F/V Angel Brailyne, F/V Bay Queen IV, F/V Carrie Anne II, F/V Gail O’ Wind, F/V Neptuna, F/V Nicole Brandy, and F/V North Lake Breeze, together with scientists Dr. Michael Stokesbury, Dr. Steven Wilson, Robbie Schallert, Jake Noguiera and Aaron Spares. Special thanks for the support of Dr. John Nielson from Canada’s Department of Fisheries and Oceans. Our gratitude to Captain Dennis Cameron for letting us use his vessel with a super fine door- for tagging. Funding was also from the TAG A Giant Foundation, the Monterey Bay Aquarium Foundation and NOAA. Congrads to our entire team. Go TEAM CANADA!!!
Monday, October 6, 2008
Our spirits still high and the fleet still optimistic, we continued the next morning on the quest for the first Canadian bluefin of 2008. Captain Dennis Cameron and mate Sheldon Gillis aboard the Bay Queen IV guided the TAG boat out of Port Hood, first stopping to jig up live mackerel, and then stopping to pull a small herring net just to make sure we had all our bases covered. After a full day of searching, those two words that make any fisherman’s blood pump…”Hook Up!”…crackled over the radio. North Lake Breeze was hooked into a 300-plus lb fish, and the TAG team scrambled to get the gear ready. The veteran Dr. Mike Stokesbury chose his lip hook and positioned the tuna mat, while making sure the flow of the hose had the proper pressure to ensure the gills would be adequately oxygenated. Dr. Barbara Block checked the tags to make sure they were on and deployable. Once the TAG boat reached the fishing vessel, a delicate handoff of the rod took place. It sounds easy, but with 5 foot seas, a 25 knot wind, and a Giant bluefin on one end, it takes fishing experts to accomplish such an inter-vessel transfer of rod and fish. Sheldon continued the fight, and after a relatively brief battle, the fish was at the leader. To see these guys fight a fish for an hour and then wire the fish effortlessly makes anyone watching feel tired! Dr. Stokesbury had the quickest lip hook to date, and the beautiful bluefin was safely on board. The fish measured over 78 inches, and Dr. Block zoomed into action. This fish got an acoustic, a pop-up, and an archival tag, and the first triple-tagged fish of the season emphatically kicked its tail back into the ocean. While we have not traditionally deployed many acoustic tags, there is a new effort called the Ocean Tracking Network that is establishing acoustic listening stations up and down the East Coast of North America. The acoustic tag on this fish will communicate with the listening stations to let us know its location whenever it is near a station.
The next day brought just as much excitement, as the team again waited with baited breath for its first call to duty. Just like the day before, on a changing tide, the silence was interrupted. This time it was the Angel Brailyne that got her hook in one. A beautiful fish measured at over 90 inches and estimated around 600 lbs because of the girth. You couldn’t have asked for a more picturesque scene…just as the fish was turned loose with its two tags (pop-up and archival), the sun set on the horizon to create one of those magical moments you remember forever.
Third Scientific Technique Confirms That Discrete Western and Eastern Bluefin Tuna Mix on North Atlantic Foraging Grounds
Tag-A-Giant Foundation Scientific Advisor Dr. Barbara Block is co-author on a new paper published in the prestigious journal, Science, entitled, "Natal Homing and Connectivity in Atlantic Bluefin Tuna Populations." The paper was published online on October 2nd and will appear in print later in the month. The study corroborates previous electronic tagging and genetics work conducted by the TAG team and others that there are two unique populations of Atlantic bluefin tuna that do not interbreed but mix on foraging grounds in the North Atlantic. This is the first research to quantify the level of mixing based on feeding area.
The paper analyzes the chemical composition of bluefin tuna otoliths, or earbones, to determine whether individuals were born in the Gulf of Mexico or the Mediterranean Sea, the only known spawning areas of western and eastern Atlantic bluefin tuna, respectively. Otoliths incorporate carbon and oxygen isotopic ratios unique to the waters in which the bluefin swims, creating a birth certificate of sorts.
Otolith samples were collected from bluefin in the Gulf of Mexico, Mid-Atlantic Bight, Gulf of Maine and Gulf of St. Lawrence in the West Atlantic, as well as the Mediterranean Sea. The results reveal a high level of mixing of Gulf of Mexico and Mediterranean Sea-spawned juvenile fish on foraging grounds in the mid-Atlantic. The percentage of Mediterranean fish decreases in the older age classes of larger fish. Interestingly, the research also shows that bluefin in northern New England and Canada are nearly entirely of Gulf of Mexico origin, suggesting that these waters may represent critical foraging habitat of the smaller, more vulnerable population that spawns in the Gulf of Mexico.
Nearly 100% of bluefin sampled on the Gulf of Mexico and Mediterranean Sea spawning grounds were found to have been born in the same area, revealing an extremely high rate of homing that exceeds the fidelity of Pacific salmon to their natal streams. This is not surprising, given previous genetic results that no more than 1 bluefin per generation (~5 years) can transfer to the other population and interbreed to maintain the observed level of genetic difference.
The research has several implications for management of bluefin tuna fisheries and is particularly timely since the international rebuilding plans for Atlantic bluefin tuna will be revisited and likely revised at the ICCAT meeting in Morocco next month. First of all, mixing rates that exceed 50% for juveniles in the Mid-Atlantic Bight confirms that the U.S. fishery is highly subsidized by fish from the eastern Atlantic population. As the eastern population has declined due to egregious levels of authorized and illegal overfishing, the depleted status of the western population has been highlighted as evidenced by the inability of U.S. fishermen to catch our quota. It is clear that current estimates of the eastern and western population size are inaccurate, and only by incorporating realistic rates of mixing in stock assessment models will we be able to reliably assess the populations.
Furthermore, while the overfishing in the Mediterranean Sea is not negatively impacting the Gulf of Mexico population, it is negatively impacting U.S. fisheries and may be largely to blame for the decreased catches in U.S. waters in recent years. This latter point should help the U.S. leverage their voice in management decisions for the Mediterranean fisheries, even if U.S. boats do not fish bluefin in the area.
Lastly, the study has shown that fish in the Gulf of Mexico, Gulf of St. Lawrence and Gulf of Maine are almost entirely from the vulnerable Gulf of Mexico population, highlighting the importance of recovery and protection efforts for bluefin tuna in these regions.
For more information, click here to visit the Tag-A-Giant Foundation page dedicated to the paper.