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June 17, 2013

A Bit More on Bluefin

Exploring the science behind bluefin tuna migrations in the Atlantic - a web extra to the SWS July 2013 feature "Bluefin Tuna Tracker"

The Atlantic bluefin tuna is an enigma, an transoceanic apex predator that seems to delight in throwing researchers and fisheries managers curve balls right around the time they think they are figuring them out. Researching my Bluefin Tuna Tracker feature for Salt Water Sportsman, I spent several hours on the phone with Dr. Molly Lutcavage, a PhD fisheries biologist and director of the Large Pelagic Research Center at the University of New Hampshire. She has decades of experience trying to unravel the mysteries surrounding bluefins and has been at the forefront of recent research that could very well rewrite much of what has been suspected about these remarkable fish.  (http://marine.unh.edu/people/faculty/lutcavage-molly.html)

Lutcavage revealed a number of interesting revelations that have come about through the use of genetic markers and DNA studies of bluefin. One that I found astounding: The latest information strongly suggests that a larger number of young-of-the-year bluefin spawned in the Eastern Atlantic swim to the waters off the East Coast of the United States, an amazing journey for fish so small, and  they appear to stay here for years. What is driving young bluefin to undertake that journey remains unexplained. Conjecture is that the Mediterranean no longer holds the forage base it once did and they truck over in search of more productive hunting grounds. Others surmise it could be simply something programmed into their DNA.

Another interesting finding is that there appears to be little spawning fidelity to the place they were born. In other words these transoceanic travelers will spawn wherever conditions are right and not necessarily in just the Med or Gulf of Mexico either. Recent captures of ripe, female bluefin just hours away from spawning have been made in the transition waters along the west side of the Gulf Stream off the U.S. coast. We have included links to some of the studies, but there is so much more to learn. There are even interactive satellite charts indicating the location and travels of tagged bluefin. We encourage you to do a little exploring of your own.

 

 

ESTIMATING THE AGE OF A BLUEFIN

NOAA Bluefin Tuna Age/Size Chart (.pdf)

 

KEY TRACKING AND SPAWNING STUDIES

Dispersal Routes and Habitat Utilization of Juvenile Atlantic Bluefin Tuna, Thunnus thynnus, Tracked with Mini PSAT and Archival Tags

New Results On Maturity Status Of Western Atlantic Bluefin Tuna, Thunnus Thynnus (.pdf)

Complex Migration Routes Of Atlantic Bluefin Tuna Question Current Population Structure Paradigm (.pdf)

Predicting Potential Atlantic Spawning Grounds Of Western Atlantic Bluefin Tuna Based On Electronic Tagging Results, 2002-2011 (.pdf)