Mote Scientist Highlights Decline of Goliath Grouper Population in New Study

August 25, 2023 – Sarasota

According to newly published data in the international, peer-reviewed scientific journal Fishes, Goliath grouper, an ecologically vital species, have experienced population declines since 2013.

This study, led by Mote Marine Laboratory & Aquarium Fisheries Habitat Ecology and Acoustics Research Program Manager Dr. James Locascio, conducted at six different spawning aggregation sites off Jupiter, FL indicate that Goliath grouper abundance had declined at all but one of six sites between 2013 and 2022.

“The Atlantic Goliath grouper is currently categorized as ‘vulnerable’ on the International Union for the Conservation of Nature. It is a long-lived species native to Florida and is an essential species for the maintenance of a balanced ecosystem. We do not want the population of this species to decline,” said Dr. Locascio.

Having almost reached extinction in the 1980s as a result of overfishing, state and federal agencies prohibited commercial and recreational harvest of the species in an effort to protect and rebuild the population. In March of 2023, the Florida Fish and Wildlife Conservation Commission (FWC) approved a limited recreational harvest of 200 Goliath grouper a year in state waters which began in the Spring of 2023.

“Mote scientists conduct today’s research for tomorrow’s ocean through innovative science and technology to help navigate the challenges of ensuring oceans thrive for generations to come,” said Mote President and CEO Dr. Michael P. Crosby. “The results of this particular study by Dr. Locascio and his colleagues will provide valuable insights into Goliath grouper population dynamics as the State of Florida reopened a limited harvest on the species after a 32-year moratorium.”

Given the data collected at multiple spawning sites in 2013 to monitor population changes, the species was showing signs of recovery. However, as part of his National Oceanic and Atmospheric Administration (NOAA) funded study, Locascio found significantly lower numbers of the Goliath grouper at most of the same historical spawning sites where previous population estimates were made. “Due to the moratorium on commercial harvest of the species there is not yet enough data to estimate future stock–recruitment or stock assessment of this species. It is our job now to provide reliable data on Atlantic Goliath grouper abundance, which are used as a prerequisite to informed management decisions,” said Dr. Locascio.

His study methods “tags” and releases a sample of the species in a way that does not affect its survival. It is an effective and reliable method that allows researchers to tag the species without catching the fish by hook-and-line and raising it out of the water, and so causes minimal disruption.

In addition to the original spawning aggregation sites off Jupiter, Florida, three additional sites off the coast of Sarasota have been identified by Locascio as spawning sites. Mote is now seeking support to use these sites to create a long-term monitoring program to track changes in the species’ abundance as is done for other iconic species. This is especially relevant as this species faces new regulations, lethal red tide events and an uncertain future after 32 years of no-harvest protection.