Linking habitat to recruitment: Evaluating the importance of pelagic Sargassum to fisheries management in the Gulf of Mexico

This project evaluates the importance of sargassum as a nursery habitat for fish in the northern Gulf of Mexico.

Figure showing potential locations of Sargassum collection (red circles). Locations based on SEAMAP Plankton survey.

The Team: Frank Hernandez (Lead Investigator, The University of Southern Mississippi,, Chuanmin Hu (University of South Florida), Kevin Dillon (The University of Southern Mississippi), Glenn Zapfe (NOAA), and Walter Ingram (NOAA)

Technical Monitor: Mandy Karnauskas (

Federal Program Officer/Point of Contact: Frank Parker (

This project began in June 2017 and will end in May 2022.

Award Amount: $1,770,853

Why it matters: Sargassum is thought to serve as nursery habitat for recreationally and commercially important fishes in the Gulf of Mexico, such as gray triggerfish and mahi mahi. However, information about the nursery function of Sargassum for juvenile life stages of these fishes is lacking, and managers know little about the environmental factors that drive variability in Sargassum abundance and distribution.

What the team is doing: To evaluate the nursery function and importance of Sargassum to fisheries in a way that is useful to fisheries managers, and to better understand the ocean and climate conditions that result in “good” Sargassum years, the researchers will measure variability in the distribution and abundance of Sargassum in the northern Gulf of Mexico. They will also assess the nursery-role function of Sargassum relative to its location and variability in different habitats (open ocean vs. nearer to shore) and the morphology (i.e. thickness) of Sargassum mats. Additionally, they will develop and test the usefulness of including measures of the capacity for Sargassum to serve as juvenile fish nursery habitat (i.e. habitat indices) in population assessments of recreationally and commercially important fish species associated with Sargassum. These habitat indices will be developed using data collected from satellites and ships in the field.

Expected Outcome: The relationship between Sargassum and fish recruitment will be used to develop a long-term forecast system to provide fishery managers with a way to link changes in weather, ocean, and climate conditions to changes in Sargassum and subsequent changes in fish recruitment. This study will try to determine if a “good” Sargassum year results in “good” recruitment for a suite of managed fisheries species.

From the seminar “Linking habitat to recruitment: Evaluating the importance of pelagic Sargassum to fisheries management in the Gulf of Mexico” 
Presenter: Dr. Frank Hernandez, University of Southern Mississippi

Other Resources

Lestrade, O., and F. Hernandez. 2021. NOAA RESTORE Science Program: linking habitat to recruitment: evaluating the importance of pelagic sargassum to fisheries management in the Gulf of Mexico: microplastic concentration and ingestion in the Northern Gulf of Mexico, 2017-07-20 to 2019-06-04 (NCEI Accession 0232040). NOAA National Centers for Environmental Information. Dataset

The seaweed bloom that covered an ocean, Isabelle Gerretsen, BBC, November 19, 2020.

How much Sargassum is in the Gulf of Mexico? Are juvenile fish that live in Sargassum more likely to survive to adulthood? Follow Weedlines, the larval fish ecology lab’s cruise blog, as they gather new Sargassum samples to help answer these questions. The cruise set sail on May 30, 2018.

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