GOLDSTEIN, J. L.*; HEPPELL, S.; BRAULT, S.; LUTCAVAGE, M. E.; University of Massachusetts Boston; University of Massachusetts Boston; Oregon State University; University of New Hampshire: Reproductive Status and Body Condition of Atlantic Bluefin Tuna in the Gulf of Maine, 2000-02: Conservation Implications

The Gulf of Maine (GOM) is an important seasonal foraging habitat for Atlantic bluefin tuna (ABT). Current management models assume that the western stock of ABT travel to the GOM annually after spawning in the Gulf of Mexico in late spring, yet recent findings from pop-up and archival tag programs suggest a more complex scenario, including trans-Atlantic migrations, multi-month residency in the central north Atlantic, and years in which some tagged animals do not return to the western Atlantic at all. In light of these new findings, we examined the reproductive status and body condition of ABT in order to define the energetic status bracketing their migration patterns outside the GOM. Data from this study may help to determine if habitat protection is needed in areas other than traditional spawning and feeding grounds. During the fishing seasons of 2000-2002, 257 ABT ranging in size from 185-291cm and weights of 75-134kg were sampled as part of an ongoing study of foraging energetics. Histological analysis identified six distinct reproductive stages for each sex. With a few exceptions, females fell into two stages: stage 1, indicating immaturity or a resting stage, and stage 6, indicating recent spawning activity. Males were found in all stages of development. Approximately 30% of female ABT landed in June and July showed signs of recent maturity, possibly indicating an alternative spawning location. A multivariate analysis will be performed to define the relationship between reproductive status and body condition, as measured by a body condition index, and adipose fat reserves.