Visual surveys are used to estimate relative abundance and to monitor the size class distribution of economically important fish species in coral reef areas of the Florida Keys National Marine Sanctuary.
Reef fish communities are a vital component of coral reef ecosystems and have major economic and ecological importance throughout the world. Increasing stressors such as overfishing, coastal development, and coral degradation makes it more important than ever to have a long term monitoring program. In 1998, the Florida Fish and Wildlife Conservation Commission (FWC) Fisheries Independent Monitoring (FIM) program started a long-term monitoring program of key reef fish species throughout the Florida Keys National Marine Sanctuary. In 2008, researchers with the Florida Fish and Wildlife Conservation Commission’s Fish and Wildlife Research Institute (FWRI) joined efforts with other agencies to perform cooperative monitoring of reef fish communities in the FL Keys coral reef ecosystem. From this collaboration, the multi-agency Reef Fish Visual Census monitoring program was developed. Other agencies involved with the monitoring include the National Oceanic and Atmospheric Administration (NOAA)’s Southeast Fisheries Science Center, the National Park Service (NPS), the University of Miami-Rosenstiel School of Marine and Atmospheric Science (RSMAS), and Nova Southeastern University (NOVA).
The Reef Visual Census (RVC) program was designed to monitor both juvenile and adult reef fish populations through time and space for selected economically and ecologically important reef fish species. The goals of the program are: (1) detect trends in reef fish habitat and reef fish species composition, abundance, and sizes; (2) assess effectiveness of marine reserves, MPA zoning, and other regulatory efforts to achieve management objectives; and (3) provide data to support habitat, ecosystem, and length-based fishery stock assessments.
The FWC-FWRI has been conducting visual census surveys since 1998, but adopted the RVC methodology in 2008. The RVC monitoring program was conducted annually until 2014, when it changed to biennial sampling on even-numbered years. Since the start of the multi-agency collaboration in 2008, over 11,000 diver surveys have been conducted in the Florida Keys region
Surveys are conducted in three regions of South Florida: Dry Tortugas/Marquesas, Florida Keys, and Southeast Florida (Miami-Dade to Martin County).
A map of the 2016 Reef Visual Census sites in the Florida Keys (not including sites in the Southeast Florida region or the Dry Tortugas)
A map showing habitat classification and select sampling sites. Different colors indicate different benthic habitats (example: orange indicates coral reef habitat while green indicates seagrass), blue circles represent sampling sites for 2016, and the black lines indicate the boundaries of Sanctuary Preservation Areas.
Sampling sites are selected using a two-stage stratified random sampling design, and then allocated to the participating agencies (FWRI, NOAA, NPS, RSMAS, and NOVA). The first stage of the stratified random sampling design divides all hard-bottom habitat under 100 feet deep into grid cells, which are then classified by habitat type (nearshore patch reef, high relief reef, etc.). Two pairs of divers will then conduct surveys at randomly selected stations within a selected grid cell for the second stage. This type of stratified random sampling design ensures that every habitat type both within and outside marine reserves are effectively surveyed, and also accounts for natural variation found within the same habitat types.
Two buddy-pairs of highly trained underwater fish observers conduct stationary point counts of all reef fish species within a 15 m diameter cylinder for a total of four fish surveys per sampling location. Once divers complete the fish survey, they will then conduct a habitat survey within their 15 m diameter cylinder. The habitat survey collects information on benthic cover, reef rugosity, and habitat type in addition to the environmental conditions such as water temperature, visibility, and depth. Surveys are generally conducted between the month of April and September and are conducted at depths up to 100’. Each RVC season, around 400 different sites are visited which amounts to 1600 individual diver surveys. Over 400,000 fish are counted each year, representing over 250 different species.
As of 2014, a subset of sites are selected for a more extensive coral demographic survey to compliment the RVC survey.
Watch an animated video of the RVC methods.
How this data is used:
Analysis of length distribution data of hogfish during the Reef Visual Census surveys in 2014 show both juvenile and adult fish sizes among populations in protected and unprotected areas of the Florida Keys and in the Dry Tortugas. Data like this can help inform managers when species are undergoing fishing regulation changes.
The Reef Visual Census program has developed a long-term database for reef fish species that has proven valuable in interpreting fisheries dependent data and developing regulations for protecting reef fish resources in the Florida Keys. Restrictions on capture and minimum sizes of most commercially important species makes it difficult to monitor life history parameters and abundance data from samples collected from the fishery. The reef fish visual census program is the only existing long term program that monitors reef fish length frequency, abundance, and life history based on fishery-independent data for the reef fish community as a whole. These data provide critical input for the state and federal agencies in the assessments of stock status and assist decision makers in the management of reef fish species in South Florida.
Citation: Brandt, M.E., N. Zurcher, A. Acosta, J.S. Ault, J.A. Bohnsack, M.W. Feeley, D.E. Harper, J.H. Hunt, T. Kellison, D.B. McClellan, M.E. Patterson, and S.G. Smith. 2009. A cooperative multi-agency reef fish monitoring protocol for the Florida Keys coral reef ecosystem. Natural Resource Report NPS/SFCN/NRR-2009/150. National Park Service, Fort Collins, Colorado.