Erin Nassif

Document Type

Internship Report

Publication Date

Spring 2017


The goals of this project were to quantify changes in the size-structure and abundance of fishes belonging to the snapper-grouper complex found throughout multiple management zones along the Florida Keys reef tract. Through the use of fishery independent Reef Visual Survey (RVC) data collected inside and out of Dry Tortugas National Park and Biscayne National Park, the status of eight reef fish species that contribute to the exploited snapper-grouper complex were analyzed. These species include the red grouper (Epinephelus morio), black grouper (Mycteroperca bonaci), hogfish (Lachnolaimus maximus), gray snapper (Lutjanus griseus), yellowtail snapper (Ocyurus chrysurus), mutton snapper (Lutjanus analis), schoolmaster snapper (Lutjanus apodus), and white grunt (Haemulon plumieri), all of which have been affected by fishing pressure. Individual population metrics including length frequency, size distribution, density, abundance, occurrence and biomass were calculated for each of the eight focal species and compared temporally across management zones. Overall it was found that Dry Tortugas National Park has higher population metrics when compared to Biscayne National Park for all focal species with the exception of schoolmaster snapper. With the use of RStudio statistical analysis software, RVC data collected over the past 17 years was able to be analyzed, processed and utilized to create informative graphical summaries of the above mentioned statistics. A set of standard operating procedures was developed through organized documentation of data analysis procedures with the hopes that subsequent users will be able to calculate the same population metrics for any of the reef fish species observed during an RVC fish count. The creation of an automated system during this project increased the efficiency of analysis, and reporting data, which will allow trends in fish populations to be better communicated to park managers and interested stakeholders.


Division: MES

MPS Track: MCO

Location: National Park Service, South Florida Carribean Network

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