Goliath Grouper Research

goliath grouper
Goliath Grouper
(Epinephelus itajara)
Photo Credit: NOAA

NOAA Fisheries Service scientists from the Southeast Fisheries Science Center (SEFSC) are working to understand the changes that have occurred in coral reef ecosystems following the loss of top predators, such as groupers. The once common Nassau grouper (Epinephelus striatus) and goliath grouper (E. itajara) have been so depleted that they are under complete protection from the South Atlantic, Gulf of Mexico, and Caribbean Fishery Management Councils exit arrow icon.

Since 1990, the goliath grouper (Epinephelus itajara) fishery has been closed to harvest throughout the southeast region of the United States (harvest was prohibited in the US Caribbean in 1993). It was listed as a candidate for listing under the Endangered Species Act in 1991 (because of the success of the harvest prohibition, it was removed in 2006).It is currently listed as "critically endangered" on the International Union for the Conservation of Nature's (IUCN, 1996) Red Listexit arrow icon

From 1997-2005, researchers at NMFS/SEFSC collaborated with Florida State University's Institute for Fishery Resource Ecology (Dr. Chris Koenig, Dr. Felicia Coleman) to monitor the status and recovery of goliath grouper. This goliath grouper research program investigated juvenile and adult jewfish abundance, distribution and migration patterns; their age and growth; and their habitat utilization. Research was conducted in the Ten Thousand Islands area of southwest Florida and in the offshore waters of the Florida Keys, the Gulf of Mexico, and South Atlantic. Florida State University investigations on goliath grouper continueexit arrow icon

Distribution, Abundance, and Habitat Needs of Juvenile Goliath Grouper

From 1997-2005, researchers studied and tagged juvenile jewfish in the Ten Thousand Islands area of Southwest Florida. Our mark-recapture study utilized trot lines and circle hooks, fish traps and blue crab traps. Some of the larger fish were fitted with sonic transmitters to allow tracking throughout the year. This sonic data revealed seasonal movement patterns and provided important information on microhabitat utilization.

Our offshore work on adult jewfish has been conducted each summer/fall spawning period since 1994. With the help of Don DeMaria we have tagged over 1000 adult jewfish and have observed aggregations of goliath grouper in both the Gulf of Mexico and more recently, the South Atlantic.

Posters created by the Center of Marine Conservation help disseminate information about our project and its requirements, highlighting our tagging study and the morphology of goliath grouper. The posters also have information on our tagging hotline so anglers and divers can call in any recapture or re-sighting information.

Age and Growth of Goliath Grouper

Given that these groupers were afforded protected status, researchers worked to utilize and develop novel non-lethal techniques to procure and analyze biological samples for life history information. Recent analysis by biologists at both the National Marine Fisheries Service SEFSC Miami and Panama City laboratories, for example, have determined that dorsal spines can be used to effectively age juvenile goliath groupers (age 0-6), instead of using otoliths (which require sacrificing the fish (Brusher and Schull, 2008). Researchers have also determined that soft dorsal rays hold promise for ageing older fish. (Murie et al, 2008).

SEFSC researchers were also the first to capture recently settled juvenile goliath grouper, describe their settlement habitat, and determine ages of these very young fish, which helps us learn about when and where the adults are spawning (Koenig et al, 2007; Lara et al, 2008).

Red Tide Impacts on Goliath Grouper

In 2003 and 2005, significant red tide events occurred in Lee and Collier Counties of Southwest Florida. Reports of manatee and turtle strandings began pouring into local and state agencies in the region, along with reports of large fish washing up dead on Southwest Florida beaches. Once these large fish were positively identified as goliath grouper, a team of biologists from the Southeast Fisheries Science Center went in search of these fish, to collect biological samples, especially otoliths (ear bones), which are valuable for determining the age of the fish. Because of the fish's protected status, researchers attempt to harm/kill as few goliaths as possible during the course of research. However, because of this, researchers lack otolith samples which are the most commonly used structure to determine the age of the fish.

These casualties, resulting from red tide, gave our biologists a unique opportunity to collect a multitude of biological samples, without having to sacrifice healthy animals. From these decomposing carcasses, biologists were able to record length for use in an age/length relationship, and were able to extract otoliths and remove dorsal spines and rays for comparison of hardparts in age and growth analysis. Tissue samples were also removed and sent to the Florida Marine Research Institute so they could evaluate the level of red tide toxin. The sampling trip gave these biologists an opportunity to educate the curious beach goers about red tide and goliath grouper (a few of which had been misidentified as baby manatees).

Assessing Population Status of Goliath Grouper

Attempts to evaluate the data needed to assess the status of these depleted stocks and develop rebuilding plans present unique challenges. In March 2003, the Gulf of Mexico Fishery Management Council exit arrow icon and the SEFSC convened a Stock Assessment Workshop, in St. Petersburg, Florida. Under the new SouthEast Data, Assessment, and Review (SEDAR) protocol, scientists, constituents, and managers evaluated the data available for a goliath grouper stock assessment. The final stock assessment, released in 2004, demonstrated that the goliath grouper stock was recovering, but that full recovery to management targets might not occur until 2020 or later (SEDAR 2004). Discussion at the meeting highlighted the need for more population level assessment work for the species, which is difficult to deliver when the species is protected from harvest (Porch et al, 2006; Cass-Calay and Schmidt, 2009).

In 2006, the National Marine Fisheries Service conducted a status review of the Goliath grouper to review whether the continental US population of goliath grouper still warranted "species of concern" status under the Endangered Species Act. The 2006 report indicated that the species was on a recovery trajectory because of current management strategies and no longer qualified for species of concern status.

In 2010, the Florida Fish and Wildlife Conservation Commission and NOAA National Marine Fisheries Service convened a benchmark goliath grouper assessment for the continental US population. That assessment is complete and the final recommendations will be forthcoming. Also in 2010, Wild Earth Guardians petitioned the US Government to list Goliath grouper under the Endangered Species Act.

This project would not have been possible without ongoing collaboration with researchers from Florida State University, Everglades National Park, and the Recreational Fishing and SCUBA Diving communities. Funding for this project was provided by NMFS Office of Protected Resources, NMFS Essential Fish Habitat Initiative, NOAA-MARFIN initiative, Everglades National Park, and the National Fish and Wildlife Foundation.

More Information/References:

Gulf and Caribbean Fisheries Institute Special Symposium:

The Status of Goliath Grouper: Finding a Common Conservation and Management Solution through a Regional Scientific and Fisheries Framework exit arrow icon

Selected goliath grouper publications from SEFSC

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