Historical declines of goliath grouper populations in South Florida, USA

Abstract

Historical data are important in fisheries management and conservation, particularly for species which suffered significant population declines prior to the collection of ecological data. The globally endangered goliath grouper Epinephelus itajara was fished intensively long before data on population size were first collected. Historical population estimates have significant management implications, as the estimated time to full recovery depends on the size of the baseline population before depletion. Evidence used previously suggests that goliath grouper populations in Florida were reduced by as much as 95% relative to estimated baseline levels at the time of protection in 1990 and have since recovered to more than 30% of these values. However, actual historic abundances are not well known because few early data exist. I present 2 new data sets: (1) historical photographs of ‘trophy fish’ and (2) newspaper articles from the Florida Keys. I analyzed goliath grouper in photos taken of fish caught on Key West charter boats from 1956 to 1985 to assess changes in abundance before the fishery was closed in 1990. The average number of individuals displayed per trip decreased before 1960 and was reduced by 86% before 1979. Further evidence of declines is found in newspaper accounts of landings (1923 to 1977), which show decreases in the maximum individual fish size caught and the proportion of large grouper caught from land vs. offshore before 1950. These results demonstrate population declines over longer time scales than are currently considered and suggest that recent increases do not represent significant recovery compared to population abundances before depletion.