Genetic discrimination of bluefin tuna spawned in the Mediterranean Sea and the Gulf of Mexico 
PI: John Graves, Jan McDowell, and Jens Carlsson
PROJECT DESCRIPTION:
This project is focused on assessing the genetic composition of yearling bluefin tuna from the U.S. mid-Atlantic region.
Previous work in our laboratory demonstrated significant differences in the distribution of mitochondrial DNA control region
sequence haplotypes and genotypes at eight nuclear microsatellite loci between young-of-the-year (YOY) bluefin tuna collected
near spawning grounds in the Mediterranean Sea and Gulf of Mexico . In the present study we will survey genetic variation of
the mtDNA control region and eight nuclear microsatellite loci of yearling bluefin tuna collected from the U.S. mid-Atlantic
region. Genetic data from YOY will be used to assign yearling fish to a spawning ground. In addition, we will increase sample
sizes of YOY fish from both areas to survey for temporal variation among year classes.
PROGRESS thru 10/31/2006:
According to the timeline presented, the first six months were to include sample collections and development of new microsatellite
markers. In addition, sequence and microsatellite analysis were set to begin at this time. To date, we have obtained the following
collections:
YOY
Gulf of Mexico : 352 potential bluefin larvae (Dr. Jay Rooker)
Mediterranean Sea: 56 YOY BFT from the Ionian Sea; year classes 2004 & 2005; processed in 2006 ( collected by Jay Rooker and awaiting shipment) and 80 juveniles from eastern Mediterranean (collected by Dr. Isak Oray)
Yearling
U.S. Mid-Atlantic: 3 specimens
2 –3 Year Old Fish
U.S. Mid-Atlantic 40 (mostly 2 and 3 year old fish)
DNA was isolated and the mitochondrial region sequenced for 36 specimens of 352 putative bluefin larvae collected during late May in the Gulf of Mexico by Jay Rooker. Sequence analysis indicated that most specimens were blackfin tuna with a few albacore, and additional analyses were not conducted. The mitochondrial control region has been sequenced from all other samples recieved to date and the eight microsatellite loci are currently being run for all samples. In addition, we are beginning to construct a microsatellite library for bluefin tuna. Although the grant stated that we would contract a company to make the library, we have had considerable success making libraries in our laboratory and have decided to do the work in-house.
PLANS FOR THE NEXT SIX MONTHS TO YEAR:
For the next six months we will screen all samples for the mtDNA control region and eight microsatellite loci. In addition, we
will augment our samples of yearling, two year old and three year old western Atlantic yearling bluefin from the NOS
laboratory in Charleston . We will also continue with the development of a new microsatellite genomic library to produce
additional microsatellite loci for the discrimination of eastern and western Atlantic bluefin tuna.
