Abstract

Unlike the terrestrial environment where comprehensive maps are readily available, maps of the ocean are scarce and usually lack the detail required to identify benthic habitats. A relatively inexpensive, commercially available product may help marine researchers overcome this obstacle. This system, distributed by Humminbird for fishermen, records sidescan imagery, bathymetry data, and GPS coordinates simultaneously and costs under $2000. The Humminbird system reveals geologic features and habitat types as well as schools of fishes and other large marine animals. The main advantages of this particular system are the sidescan component and the ability to record all the imagery, maps, and coordinates on to a SD card. The recorded data can be downloaded to a computer, converted into a more usable format and then incorporated into ArcGIS to create georeferenced habitat maps. Using the Humminbird, I mapped several artificial reefs and hardbottom sites in the northeastern Gulf of Mexico and verified the imagery with dive surveys. The mapping methods were improved as the study progressed and ideally consist of recording one parallel transect at a time by starting the recording at the beginning of each transect and stopping it at the end. This greatly reduces the amount of post-processing and makes the imagery easier to manage. Relatively small ledges, rocks, and reef balls can be identified and accurately mapped using this approach. The Humminbird system has great potential and should benefit future reef fish research and provide essential maps for effective-ly implementing ecosystem based management.

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