Saturday, March 15, 2008

Archival Tagged Bluefin Recaptured in the Gulf of Mexico

The lab was a buzz with the news that an Atlantic bluefin tuna released in January of 2004 from North Carolina and implanted with an archival tag, was recaptured by a US longliner operating in the Gulf of Mexico. We look forward to receiving the tag the first ever returned in US waters on the spawning ground. We've been able for years to piece together the tracks of bluefin who move into the Gulf to breed from North Carolina, and New England releases, and from release of Pop up satellite tags from Gulf fish, but never have we obtained an archival tag- that is from the recent generation of our archival program- with this much promise. One Caveat, is this tuna is carrying an archival tag of the A-series in our long Development history of electronic tags- if only it had been D-series, I'd be super excited. The tags with an A have had a battery issue where after 700-800 days at sea in a warm tuna body the battery slowly corrodes and due to a mathematical error early on we do not pulse enough juice to remove the corrosion- this is called passivation. We all know what happens when batteries give out- fortunately we do get the data up until the battery fails. But.. there is good news- as we set the tag up for 120 seconds- a slow sampling rate, which should if all went well...give us potentially a 1000 day track or more. Now I may be counting my chickens too soon, but folks we've rarely ever been this enthusiastic to see an archival tag returned. More soon- when the tag arrives. So much has to work-Our tags are essentially computers- about as expensive, placed gently at sea into the body cavity of a bluefin- in this case it has within the fish, for years been taking data, and we can only hope that the tag, has remained intact and that when this large fish left the deck of the F/V Calcutta our surgery boat, we did not knock the light stalk a very thin Teflon coated sensor that carries the most delicate looking string of sensors you've seen. I hope it works.