Absolute Abundance Estimates of Atlantic Goliath Grouper (Epinephelus itajara) on Spawning Aggregation Sites (original) (raw)
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Endangered Species Research, 2009
In early 2006, NOAA National Marine Fisheries Service removed goliath grouper from its list of species of concern. It cited a recent status report that showed a significant increase in the abundance of the USA population and suggested that goliath grouper are re-establishing themselves throughout their historic range. However, under the Magnuson-Stevens Conservation Act, the goliath grouper remains 'overfished,' and harvest is still illegal. The historical center of abundance of goliath grouper is the Ten Thousand Islands area of southwest Florida. Detailed catch and effort data are available from this region for 1973 to 2006. The data were collected by Everglades National Park (ENP) officials during voluntary dockside interviews of sport fishermen. Using this data, a standardized index of abundance was created for juvenile goliath grouper. The index shows a substantial decline in abundance during the late 1970s and early 1980s. Since that time, the abundance of juveniles within ENP has increased considerably, suggesting that strong year classes have recently occurred in ENP. This information is useful for managers and stock assessment biologists tasked to evaluate the stock status of goliath grouper, and to determine acceptable harvest levels for scientific research and/or fishing.
Gulf of Mexico Science
Two visual surveys are examined for evidence that the number of goliath grouper has increased in the waters off South Florida since a harvest moratorium was imposed in 1990. Both surveys are standardized to account for the unbalanced design of the sampling procedure. The first survey is effectively a census of the number of goliath grouper at five artificial reef sites in the Gulf of Mexico about 90 miles north of Key West, Florida. It is standardized by use of the canonical log-linear model. The second survey includes the observations of many different SCUBA divers at 32 sites scattered along the Atlantic coast of Florida from the Dry Tortugas to Jupiter. The canonical log-linear model is not appropriate for standardizing this data set because observations of 2 to 10 fish are recorded only as 2 or more. To accommodate this feature, we developed a standardization procedure based on a censored Poisson distribution. The most important factors in standardizing the two surveys were the year and location. Seasonal effects were also statistically significant, but had little impact on the results because most of the dives in any given year were conducted during the 'warm' season. Both of the standardized series indicate a substantial increase in abundance since the 1990 moratorium.
Pattern of Recovery of the Goliath Grouper Epinephelus itajara Population in the Southeastern US
Bulletin of Marine Science, 2011
In the present study, we evaluate the past and current distribution and abundance of the Atlantic goliath grouper, Epinephelus itajara (Lichtenstein, 1822), in coastal waters of the southeastern United States. The study is based on quantitative surveys conducted by us (n = 190) and the Florida Fish and Wildlife Conservation Commission's Artificial Reef Program (n = 505), coupled with semi-quantitative data submitted by volunteer divers to the Reef Environmental Education Foundation (n = 27,542) over the past 15+ yrs. The vast majority of the goliath grouper population is restricted to Florida waters. We found that the population of goliath grouper, after dramatic fishery-induced declines in the 1970s and 1980s, and eventual fishery closure in the 1990s, increased off southwest Florida in the mid-1990s, directly offshore of the high-quality mangrove nursery of the Ten Thousand Islands. It then expanded north and south, eventually increasing off Florida's central east coast. Tagged fish, regardless of life stage, showed strong site fidelity to home sites: juveniles (2963 tagged, 32.6% recaptured) to mangrove nursery sites and adults (2110 tagged, 7.6% recaptured) to offshore reefs. All long-distance movements appeared to be in response to approaching maturity, with juveniles emigrating from mangroves to take up residence on offshore reefs, to seasonal spawning activity, with adults moving from home sites to aggregation sites, or to apparent feeding sites in inlets. Understanding these patterns of population recovery and movement is fundamental to devising appropriate management policies.
Pattern of Recovery of the Goliath Grouper Epinephelus itajara Population in the Southeastern US
Bulletin of Marine Science, 2011
in the present study, we evaluate the past and current distribution and abundance of the atlantic goliath grouper, Epinephelus itajara (lichtenstein, 1822), in coastal waters of the southeastern united states. The study is based on quantitative surveys conducted by us (n = 190) and the florida fish and Wildlife conservation commission's artificial reef Program (n = 505), coupled with semi-quantitative data submitted by volunteer divers to the reef environmental education foundation (n = 27,542) over the past 15+ yrs. The vast majority of the goliath grouper population is restricted to florida waters. We found that the population of goliath grouper, after dramatic fishery-induced declines in the 1970s and 1980s, and eventual fishery closure in the 1990s, increased off southwest florida in the mid-1990s, directly offshore of the high-quality mangrove nursery of the ten Thousand islands. it then expanded north and south, eventually increasing off florida's central east coast. tagged fish, regardless of life stage, showed strong site fidelity to home sites: juveniles (2963 tagged, 32.6% recaptured) to mangrove nursery sites and adults (2110 tagged, 7.6% recaptured) to offshore reefs. all long-distance movements appeared to be in response to approaching maturity, with juveniles emigrating from mangroves to take up residence on offshore reefs, to seasonal spawning activity, with adults moving from home sites to aggregation sites, or to apparent feeding sites in inlets. understanding these patterns of population recovery and movement is fundamental to devising appropriate management policies.
Fishery Bulletin- National Oceanic and Atmospheric Administration
Many modern stock assessment methods provide the machinery for determining the status of a stock in relation to certain reference points and for estimating how quickly a stock can be rebuilt. However, these methods typically require catch data, which are not always available. We introduce a model-based framework for estimating reference points, stock status, and recovery times in situations where catch data and other measures of absolute abundance are unavailable. The specif ic estimator developed is essentially an agestructured production model recast in terms relative to pre-exploitation levels. A Bayesian estimation scheme is adopted to allow the incorporation of pertinent auxiliary information such as might be obtained from meta-analyses of similar stocks or anecdotal observations. The approach is applied to the population of goliath grouper (Epinephelus itajara) off southern Florida, for which there are three indices of relative abundance but no reliable catch data. The results confirm anecdotal accounts of a marked decline in abundance during the 1980s followed by a substantial increase after the harvest of goliath grouper was banned in 1990. The ban appears to have reduced fishing pressure to between 10% and 50% of the levels observed during the 1980s. Nevertheless, the predicted fishing mortality rate under the ban appears to remain substantial, perhaps owing to illegal harvest and depth-related release mortality. As a result, the base model predicts that there is less than a 40% chance that the spawning biomass will recover to a level that would produce a 50% spawning potential ratio.
Recovery of the Goliath Grouper (Epinephelus itajara) Population of the Southeastern U.S
2009
Reef fishes across the globe are threatened by human exploitation as well as the adverse effects of pollution, habitat destruction, and climate change. Many species are fished almost out of existence. One such species is the goliath grouper, Epinephelus itajara, which is considered critically endangered by the IUCN throughout most of their range from North Carolina to Brazil in the western Atlantic and from Senegal to the Congo in the eastern Atlantic (the Pacific population was recently deemed a separate species, E. quinquefasciatus (Craig et al. 2009)). The exception to this depletion is in Florida, where goliath grouper populations have been recovering since the fishery closure in 1990. The dive surveys submitted by volunteer dive surveyors to the Reef Environmental Education Foundation (REEF) over the past 15+ years (n = 27,542) document the recovery of goliath grouper throughout their former range in the United States. The recovering population initially increased off southwest...
Spawning Migrations of the Atlantic Goliath Grouper along the Florida Atlantic Coast
Fishes
Atlantic goliath grouper (Epinephelus itajara), the largest reef fish in the Western Atlantic, exhibit high site fidelity to home reefs but also undertake annual migrations to distant spawning sites. Once relatively common throughout Florida and the Caribbean, the species; is now considered vulnerable (i.e., threatened with extinction) due to overfishing and loss of juvenile mangrove habitat. Goliath grouper in the southeastern US form annual spawning aggregations on high-relief reefs located offshore of both the Gulf and Atlantic coasts of Florida, US. To determine spawning site fidelity and describe migration patterns to aggregations, we implanted 50 adult goliath grouper with acoustic transmitter tags from 2010 to 2013. Fish were tagged at known spawning sites off the Florida Atlantic coast and tracked as they moved through the FACT Network array of acoustic receivers. From 2010 to 2020, we collected ~7 million detections from tagged goliath grouper at 153 sites along the southea...