OLI Grant: Understanding the Distribution of Atlantic Bluefin Tuna in a Physical Oceanographic Context

Amy Bower, Physical Oceanography

Grant Funded: 2006

Atlantic bluefin tuna populations in the western North Atlantic have declined precipitously (by ~80%) over the past 30 years due to overexploitation. To help develop effective management and conservation plans, biological oceanographers have for the last decade been tracking these wide-ranging fish with electronic tags to document their migratory, feeding, and spawning behavior. In a recent paper in the journal Nature, Block et al. (2005) reported that bluefin tuna from both the western and eastern Atlantic populations exhibit a preference for foraging near and inshore of the Gulf Stream and North Atlantic Current from Cape Hatteras to north of the Grand Banks of Newfoundland. To explain the distributions of foraging bluefin tuna, and predict how they might be affected by climate change, we need to better understand the fundamental physical and biological factors that influence where tuna congregate.

I propose to explore this research topic by developing an interdisciplinary collaboration with Dr. Barbara Block of Stanford University, a biological oceanographer and a leader in the tagging of bluefin tuna and other pelagic species in the Atlantic and Pacific Oceans. I am a physical oceanographer with 20 years of research experience studying the structure and dynamics of the Gulf Stream, North Atlantic Current, and adjacent water masses. I am requesting support to conduct a preliminary analysis of the data collected by foraging bluefin tuna, including latitude, longitude, and temperature versus depth profiles, from a "hot spot" in tuna concentration east of the Grand Banks.  These data will be compared to subsurface float, sea surface temperature (SST), SeaWiFS, and surface current data to develop some initial intuition on the relationships between tuna behavior and the physical environment. Funds are also requested to visit Dr. Block at Stanford and to host one of her PhD students for one or two weeks here at WHOI in order to exchange information. This work will be carried out to prepare for a more substantial externally-funded interdisciplinary study which would include an in-depth analysis of the tag and other relevant oceanographic data from the wider Gulf Stream region, and possibly new collaborative field work. Dr. Block has indicated her commitment to building this collaboration by offering to match up to two months of salary support obtained through this proposal.