Size of Prey Matters Most.

• Position: BLUEFIN TUNA - Atlantic herring - Brief article

Bluefin tuna are going hungry in a sea full of fish because their foraging habits are most efficient with larger--not necessarily more abundant --prey, according to a study led by Walter Golet, assistant research professor in the School of Marine Sciences at the University of Maine, Orono.

The Gulf of Maine is an important foraging ground for bluefin tuna (Thun-nus thynnus). Their preferred prey is Atlantic herring (Clupea harengus). Tuna spend up to six months in the Gulf consuming high-energy prey such as the herring and, in doing so, accumulate as much as 200 pounds in fat. Energy acquired in the Gulf of Maine is vital to support bluefin tuna migration and reproduction.

The population of Atlantic herring has increased over the past two decades, suggesting that foraging conditions should have been favorable for bluefin tuna. A decline in bluefin tuna despite abundant prey resources was puzzling, so the researchers tested hypotheses related to the energetic payoff of eating herring of various...