December 5, 2025 — Atlantic bluefin tuna are prized by both recreational and commercial fishermen. In 2022 alone, U.S. commercial fishermen generated an estimated $12.4 million in revenue from harvesting bluefin tuna. However, they are also among the most challenging species to study, as they migrate long distances and live in the open ocean for much of the year.
NOAA Fisheries recently embarked on a cooperative research project to understand Atlantic bluefin tuna reproduction (also known as spawning) in the Slope Sea. Scientists infrequently sample this area of the ocean between the Gulf Stream and the continental shelf of the Northeast United States. It may contain a crucial missing piece for understanding the overall population structure of bluefin tuna in the Atlantic.
Historically, this species has been managed as having two primary stocks:
- Eastern stock that spawns in the Mediterranean Sea
- Western stock that spawns at older ages in the Gulf of America
Dr. Molly Lutcavage’s lab at the Large Pelagics Research Center in Gloucester, Massachusetts is conducting research on reproduction and electronic tagging. The lab is affiliated with UMass Dartmouth’s School for Marine Science & Technology. Their research suggested that spawning might be occurring in other areas of the western Atlantic as well, and by younger, smaller fish. Lutcavage’s lab predicted that smaller fish would spawn closer to feeding grounds. Biological evidence from NOAA Fisheries larval fish sampling in the Slope Sea supported this hypothesis. Recent genetic research shows the stocks are interconnected. However, there was little data available on the reproductive condition of adult bluefin tuna, including smaller adults, in the Slope Sea to corroborate these studies—until now.