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Research Spotlight: Diving into Goliath Grouper Research

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The giant of the grouper family, the goliath, can reach lengths of eight feet or more and may exceed 800 pounds. While this monster fish makes for an impressive catch, harvest of this species was banned in U.S. waters in 1990, after a noted sharp decline in populations. After years of protection, increasing reports of sightings are accompanied by a growing sentiment that the species is recovering. However, the data needed to assess the status of this species are limited. As the species remains protected from harvest, researchers are not able to collect data in some of the traditional ways, such as gathering harvest statistics or collecting specimens for analysis.

To address this issue, FWC Fish and Wildlife Research Institute biologist Angela Collins established a cooperative research project to observe and tag goliath grouper along Florida's central west coast. Through this collaborative project with the St. Petersburg Underwater Club, researchers hope to identify potential patterns in the numbers of goliath grouper by season and by size relative to different habitats, as well as learn about the species' behavior and life history.

Since November 2007, Collins has performed over 350 dives at 78 survey sites to collect data in both natural and artificial (man-made) habitats at a variety of water depths. During each dive, Collins thoroughly assesses the entire site and records the number of goliath grouper. Collins uses underwater video to document the goliath grouper she observes. During filming, she projects visible dots onto the fish using a set of lasers fitted to the top of the camera. Back at the lab, researchers import the still frames of the recorded fish into a software program to analyze the image and estimate the size of the fish based on the distance between the laser points.

Following the initial underwater observations, divers also dart-tag some of the fish they observe using a modified spear gun. On subsequent surveys, divers note any tagged fish they see and angler reports of fish captures are encouraged as the FWC Angler Tag Return Hotline is printed on each tag.