Florida Keys Reef Fish Monitoring: Reef Fish Visual Census

By Alejandro Acosta, Jennifer Herbig, Jessica Keller, Danielle Morley and Colin Howe

In the Keys, the finfish team was hard at work during 2018, collecting data for the biennial reef fish underwater visual census. Underwater visual census methods are used worldwide to survey shallow aquatic habitats. These methods are suited to monitoring the abundance of coral reef fish because it allows for the collection of community level data without the disturbance inherent in other, more destructive sampling techniques. The finfish team monitors reef fish assemblages and benthic components with the objective of detecting changes in reef fish communities over time.

This is a multi-agency partnership that includes the National Oceanic Atmospheric Administration, National Park Service, and University of Miami-Rosenstiel School of Marine and Atmospheric Science and we rely on each other to complete the sampling. The RVC survey is a probability-based stratified random sampling survey that focus hard bottom habitat in depths less than 30m.  Sites are chosen by using a two-stage stratified-random sampling design based on depth and habitat.  Habitat with higher complexity has more fish, and therefore higher variance.  To improve sampling accuracy, more sites are allocated to habitats with higher complexity.    Targeting locations that represent important habitat for many fish species, scientists visit each of these sites to observe the size, species, and number of fishes within their sample location.

More than 4,000 individual fish surveys were conducted during the 2018 RVC season in South Florida, and the eight members of the finfish team conducted 452 of these surveys at 113 sites in the middle Keys.  They counted 89,464 individual fish, representing 187 species. FWC uses data from these surveys to help inform management decisions. For example, data from the RVCs were recently used to support the continuation of the Research Natural Area (a no-take marine reserve) in the Dry Tortugas for the next 20 years.  Data are also used in stock assessments, like the upcoming SEDAR 64 for Southeastern Yellowtail Snapper.  For more information, check the link. http://myfwc.com/research/saltwater/fish/research/fim-fl-keys-visual-sampling/

Sampling domain of the Florida Keys Reef Fish Monitoring. Each purple dot represents a survey conducted by the finfish team in 2018 in the middle Florida Keys.