Importance of Incorporating Digital Imaging Technology into Broad-Scale Surveys of Reef-Fish Assemblages: Lessons Learned from the West Florida Shelf

Reef fish populations have long supported lucrative commercial and recreational fisheries throughout much of the southeastern United States.  Recent stock assessments indicate that several high-profile reef fishes (e.g., gag, red snapper) are currently overfished and/or undergoing overfishing, necessitating restrictive management regulations designed to allow these stocks to rebuild.  To date, the assessment of exploited reef fishes has been hampered by the relative paucity of fisheries-independent data.  Accordingly, state and federal agencies have begun to address these limitations collaboratively through modified and/or expanded fisheries-independent surveys along both the Gulf of Mexico and South Atlantic coasts.  Monitoring efforts initiated by the Florida Fish and Wildlife Conservation Commission on the West Florida Shelf, which include water depths ranging from 10 – 110m, rely on the integration of underwater imaging technologies with traditionally-used capture gears as part of a holistic approach to characterize fisheries resources and associated benthic habitats.  We present an overview of the development of this monitoring program and early results that highlight the logistical challenges associated with the design and implementation of a broad-scale survey of reef-fish assemblages as well as the importance of incorporating technology to overcome these challenges.  To date, the biggest logistical challenge has been locating reef habitat due to the lack of broad-scale, high-resolution habitat data.  Mapping the entire West Florida Shelf survey area is an unrealistic goal due to cost and time requirements.  Instead, real-time mapping surveys using side-scan sonar are conducted prior to deploying the sampling gear to identify reef stations to be sampled the following day.  Surveys of reef stations involve a multi-gear approach using stationary underwater video camera arrays as well as capture gears (e.g., chevron traps, passive hooked gears).  Videos and still images from the camera arrays are analyzed to quantify and measure reef-associated nekton as well as characterize surrounding bottom habitat.  Capture gears, which are also equipped with underwater cameras, are used to quantify select reef-associated fishes as well as provide demographic data.  Integrating imagery from underwater cameras allow us to ground-truth side-scan sonar as well as post-stratify data when conducting species-specific analyses.  Ultimately, our goal is to use these data to develop a habitat-based approach to stratify and allocate sampling effort to improve overall survey efficiency and provide more accurate estimates of species-specific relative abundances.