The goal of this research was to develop statistically robust ecosystem-based approaches, while optimizing data acquisition on relatively unexploited fish species in South Florida reefs, i.e., parrotfishes, Family Scaridae, in Biscayne Bay (with seasonal roller frame beam trawl surveys, 1996-2000) and Florida Keys (with annual Reef Fish Visual Censuses, 1997-2001), by following these steps: (I) analysis of information gaps for the stocks, including systematics, biogeography, population dynamics, reproductive ecology, trophodynamics, habitat use, and fisheries dynamics of Western Atlantic parrotfishes; (II) determination of primary research objectives from prioritization in Step I; (III) determination of essential fish habitats, ontogenetic shifts, migrations, and reef-seagrass habitat, from integration of stratified sampling design for fisheries-independent surveys, habitat selection theory-based analyses, and length-based analyses; (IV) estimation of population dynamics and fisheries-specific parameters encompassing life history demographics from empirical data or comparisons to theoretical expectations adapted to local conditions; (V) simulation modeling of a realistic range of fishing scenarios and demographic characteristics to evaluate the efficacy of potential traditional fisheries and spatial management strategies; and (VI) application of sampling optimization procedures and fisheries ecology approaches. Four scarid species had an estimated combined abundance of ca. 36.8 x 106 individuals in the Florida Keys. Connectivity among seagrass beds, coral reefs and deep waters had three major patterns: seagrass dwellers, reef dwellers, with inshore-to-offshore ontogenetic , and a seagrass-reef connection, using Biscayne Bay as an important recruitment ground. Marine protected areas of the Florida Keys National Marine Sanctuary did not show effects on abundance, size composition or spatial distribution of any parrotfish studied. Simulations suggested relatively short longevities (5-10 years), moderate body growth curvature, high instantaneous natural mortality rates (0.3-0.6 y super minus one), and low annual survival rates (27-54%). Simulated estimates of fishing mortalities ranged from 0.3 to 0.6 y super minus one, indicating low levels of exploitation, but low Spawning Potential Ratios (SPR = 23.5-26%). Proposed potential exploitation based on a legal minimum size equal to their size at first maturity and fishing rates equal or below to their natural mortality should secure SPR values at 45-48%.

This study examined the effects of the January 2010 cold spell on mangrove utilizing coral reef fishes off the southeast coast of Florida, USA, in the vicinity of Biscayne National Park (BNP). An ongoing, fishery-independent mangrove visual survey documenting fish assemblages in BNP provided data from the years 1998 to 2014 for examination. Of particular interest were the presence, abundance, and size structure for five mangrove utilizing coral reef fishes: sergeant major (Abudefduf saxatilis), yellowfin mojarra (Gerres cinereus), schoolmaster snapper (Lutjanus apodus), gray snapper (Lutjanus griseus), and great barracuda (Sphyraena barracuda). These species were selected for analysis due to their economic and ecologic importance, their potential as environmental indicators, their connectedness to multiple habitats, and their abundance within the available data set. Data were collected using a modified visual ‘belt transect’ method, consisting of 60 m2 transects running parallel to the mangrove shorelines. Data for average length of fish were reconstructed to form standard normal distributions and the resulting lengths were assigned to various age-classes to create species-specific length-frequency distributions. Variations in presence and abundance were examined across three time periods (1998-2009; 2010-2011; 2012-2014), as well as comparisons of length-frequency distributions. Following the January 2010 cold spell, the presence and abundance values for the two years immediately following the event were significantly decreased compared to the years prior to the cold spell for most of the five species at either mainland (ML) or leeward key (LK) locations. Additionally, the presence and abundance estimates typically remained statistically decreased when compared against the remaining years in the available data set. The size structures for the majority of the five species at either location, however, were not consistently significantly different between the three time periods, as was hypothesized. Instead, the analyses showed mixed results, with the size structure typically shifting towards smaller individuals immediately following the event. These findings suggest that drops in water temperature resulting from cold spells are capable of directly impacting mangrove utilizing reef fish species, albeit to varying degrees depending on various factors, such as physiological tolerances, ecological life history strategies, and habitat requirements.