August 21, 2025 — A researcher at the University of Maine’s Pelagic Fisheries Lab conducted a study about Atlantic bluefin tuna and observed surprising changes in the fish’s diet.

This prized species of fish is shifting away from eating herring and now consuming menhaden as its primary prey.

What’s happening?

As the university shared on Phys.org, researcher Sammi Nadeau published the study in the journal Marine Ecology Progress Series.

Atlantic herring in the Gulf of Maine have been dramatically declining in population. Without ample herring to eat, Atlantic bluefin tuna began eating another fatty pelagic fish, menhaden.

Menhaden is not only a primary food source now for Atlantic bluefin tuna but also an essential ingredient in commercial fish oils. Understanding how vital menhaden have become commercially and in the natural food chain, scientists are recommending fishing limits to reduce the burden on menhaden populations.

Read the full article at The Cool Down