Reef Fish Survey Team in the Southeast
The Reef Fish Survey Team conducts fishery independent surveys.
The Reef Fish Survey Team conducts fishery independent surveys to provide spatially-explicit demographic and biological information linked to habitat parameters for economically and ecologically important reef fish. The specific goal is to enhance fishery ecosystem model development and management. A variety of methods are employed to collect information which is unavailable through traditional means.
Methodology and Gear
Stationary Video Camera Array
This array is composed of four orthogonally (perpendicular) spaced video cameras to determine relative abundance of fish and percent cover of habitat. The array has no lights, does not move, and emits no sounds and therefore provides more accurate data on fishes than a remotely operated vehicle—called an ROV—because it does not modify their behavior as much. However, data collected from the array is far more restricted geographically due to its static positioning.
These new cameras consist of a stereo head (two cameras simultaneously recording paired images), a video camera, a computer to record data, and control functions, all inside a pressure housing. The advantage of these cameras is they provide not only video data, but paired still images that can be run through Vision Measurement Software to provide length data for most fish in the field of view.
Chevron Fish Trap
A limited number of traps are dropped on sample sites after the video array has been recovered. A random number of fish are collected to determine age and size structure of local populations, as well as determine spawning condition. All fish collected are measured, weighed, and have otoliths and gonads removed for age, growth, and reproductive studies.
A SeaBird SB-19+ is dropped on each sample site either during or after the camera array deployment. This instrument provides full water column measurements of depth, salinity, temperature, dissolved oxygen, and light transmissivity at each station.
Side Scan Sonar
Remotely Operated Vehicle
The ROV provides continuous live video data of fish and habitat within the study areas. The video footage is used to delineate and quantify habitat types, as well as fish species presence and density within each habitat type. A ROV tracking system allows geo-referencing of fish and habitat data, and also allows for estimates of fish abundance per area. Our Seabotix LBV 3002 is capable of diving to depths of 100 meters and is equipped with scaling lasers so that fish size may be estimated.
The Gulf of Mexico, specifically the West Florida Shelf, is an area that supports a large quantity of reef fish species. Although their numbers are economically significant to both commercial and recreational fisheries, only approximately two percent of the shelf has been mapped with sufficient resolution to locate and quantify the hard bottom habitat these reef fish are so strongly tied to. Such maps are essential for designing an efficient fishery independent survey of reef fishes, enabling pre-stratification by habitat, and thereby minimizing variance and optimizing survey resource. Utilizing side-scan sonar to conduct cross shelf transects in the Northern Gulf of Mexico to locate and classify areas of hard bottom reef allowed us to create a landscape picture of the benthic terrain which is further broken down with a classification scheme to then identify hard bottom areas into pre-made geoform categories (i.e., ledge, hard bottom, fracture, etc.). We have found significant differences in distribution and extent of hard bottom geoforms, both by depth and spatially east and west of Cape San Blas, a known zoogeographic feature. Hard bottom distribution is not uniform and can vary from greater than four percent to less than one percent depending on the area.
We began mapping cross-shelf transects on the northern West Florida Shelf using a Marine Sonic HDS 600/1200 kHz side scan sonar in the spring of 2010. In seven days, ten single swath cross-shelf transects approximately 20 to 30 nanometers by 150 meters, primarily in depths from 10 to 30 meters, were mapped in Apalachee Bay in the Florida Big Bend, yielding approximately 1,400 new hard bottom sites. Additionally, 355 sites were found in a 13.2 square kilometer area of high relief (up to 10 meters) off Panama City. An inexpensive live video drop camera, a high definition video camera array, and occasionally a remotely operated vehicle were used for visual ground truthing of a select number of the side scan targets. Ground truthing specific targets from side scan data proved to be very useful in developing a habitat classification scheme. From this we were able to classify habitat types, as well as measure habitat relief and area in an effort to sample a variety of reef types in our surveys. Since 2010, we have found over 4,000 hard bottom sites on the West Florida Shelf.