Implications of reef fish movement from unreported artificial reef sites in the northern Gulf of Mexico

Artificial reefs were deployed in the northeastern Gulf of Mexico (GOM) by the state of Florida's marine fisheries agency but not reported to the public in an attempt to create no-harvest refuges for exploited fishes. As part of a broader examination of the efficacy of this approach, a tagging study was conducted at a subset (n = 9) of these unreported artificial reefs to examine the likelihood that reef fishes would remain associated with them and to test factors affecting species-specific movement. Quarterly tagging trips (n = 12) were made between March 2005 and December 2007 during which 3109 fish among 12 species were tagged with internal anchor tags. Red snapper (Lutjanus campechanus, n = 2114), gray triggerfish (Balistes capriscus, n = 267), and groupers (Family: Serranidae, n = 148), were among the most frequently tagged fishes. Eighty-six fish were recaptured on subsequent tagging trips and fishermen reported 249 recaptures caught away from study sites. Mean (SD) distance moved among recaptures with reported recapture location was 37.1 (6.6) km for red snapper (n = 173), 8.8 (3.1) km for gray triggerfish (n = 47), and 25.2 (14.9) km for groupers (n = 26). During the study, a hurricane passed over the study area, thus adding an unplanned factor to movement analyses. Fish size, reef depth, time free, and hurricane exposure significantly affected the likelihood of red snapper movement (p < 0.020), but only fish size significantly affected distance moved (p = 0.036). No factors significantly affected gray triggerfish movement, and low sample size precluded statistical tests of grouper movement. Overall, results indicate that large scale (>100 km) red snapper movement was not dependent on hurricane occurrence, while gray triggerfish displayed mostly limited (<10 km) movement irrespective of factors tested. The scale of movement observed suggests the efficacy of unreported artificial reefs to serve as no-harvest refuges is doubtful, especially when regional fishing mortality is high. Marine protected areas may be an effective alternative approach to facilitate the recovery of overfished stocks, but would need to be expansive to account for reef fish movement.