Suwannee Regional Reef Program Summary

Extracted from document ‘Grant Number C-6729 Final Project Report: Fundamental Design Parameters for Artificial Reefs: Interaction of Patch Reef Spacing and Size.’ Reference code 2211413. Off the mouth of the Suwannee River along Florida's north-central Gulf coast, University of Florida researchers began a program m 1990 to answer many questions regarding the use of artificial reefs for fishery management. Specifically, the program is seeking to answer two important questions: ( 1) How much fishing can take place at an artificial reef site before the fish caught exceeds the fish produced by that reef? And (2) To what extent can the balance between fish harvested and fish produced be shifted to maximize the sustainable fish populations at managed reef sites? In addition to answering these questions, the research is providing new information to improve reef designs and how to place them for best results. At the onset of the program, 22 artificial reef sites known as the Suwannee Regional Reef System were developed as the largest experiment of its kind in the nation. Located along the 40-foot depth contour, the reefs are approximately 15 nautical miles offshore and bracket the mouth of the Suwannee River. Each site has six patch reefs spaced either 25, 75, or 225 meters apart. Each of the reefs consists of either four or 16 prefabricated concrete cubes with horizontal 55 gallon drums as central cavities. The reefs were constructed with funds collected from the sale of Florida saltwater fishing licenses. With funding from the Department of Environmental Protection's Marine Resources Grants Program (saltwater fishing license revenues), the initial study of these reefs from 1991-1995 provided the following findings: *Although it takes time, gag grouper eventually find that they like living on the artificial reefs. Gag populations increased steadily over the first five years of the project—especially on patch reef with 16 cubes. By the fifth summer of the program, the 16 cube reefs placed 225 meters apart had an average gag population of 400 fish per site. In fact, gag grouper accounted for almost 42% of the total fish weight at all reefs. However, as gag populations increased, the number of black sea bass and adult tomtate decreased from several hundred fish per site to virtually none. *The total fish abundance and biomass was significantly greater on 16-cube reefs than on 4- cube reefs. But despite having four times as many cubes, there were only two to three times as many fish at the 16-cube sites. *Some fish that shelter at the reefs and forage over sand bottom had a distinct preference for reefs spaced 225 meters apart. For example, black sea bass, white grunt, cubbyu and gray triggerfish all prepared to maximize the spacing between reefs. On the other hand, adult tomtate and sheepshead, both of which display the same shelter and forage characteristics, did not seem to care about reef spacing.