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Seasonal Variation in Sea Turtle Density and Abundance in the Southeast Florida Current and Surrounding Waters.

Bovery CM, Wyneken J - PLoS ONE (2015)

Bottom Line: This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current.Density of sea turtles observed within the study area ranged from 0.003 turtles km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012.This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, United States of America.

ABSTRACT
Assessment and management of sea turtle populations is often limited by a lack of available data pertaining to at-sea distributions at appropriate spatial and temporal resolutions. Assessing the spatial and temporal distributions of marine turtles in an open system poses both observational and analytical challenges due to the turtles' highly migratory nature. Surface counts of marine turtles in waters along the southern part of Florida's east coast were made in and adjacent to the southeast portion of the Florida Current using standard aerial surveys during 2011 and 2012 to assess their seasonal presence. This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current. While it is understood that marine turtles use these waters, here we evaluate seasonal variation in sea turtle abundance and density over two years. Density of sea turtles observed within the study area ranged from 0.003 turtles km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012. This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species.

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Sightings of the two most commonly observed sea turtle species in 2011–2012 by season.Loggerheads (top panels) and green turtles (bottom panels) sighted in each season during 2011–2012 aerial surveys. Note that the highest numbers of loggerheads sighted is in the spring while the highest numbers of green turtles sighted is in the summer. Each symbol represents a single sea turtle. Dotted lines represent the approximate location of the core of the Florida Current. Source: Florida Fish and Wildlife Conservation Commission-Fish and Wildlife Research Institute.
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pone.0145980.g003: Sightings of the two most commonly observed sea turtle species in 2011–2012 by season.Loggerheads (top panels) and green turtles (bottom panels) sighted in each season during 2011–2012 aerial surveys. Note that the highest numbers of loggerheads sighted is in the spring while the highest numbers of green turtles sighted is in the summer. Each symbol represents a single sea turtle. Dotted lines represent the approximate location of the core of the Florida Current. Source: Florida Fish and Wildlife Conservation Commission-Fish and Wildlife Research Institute.

Mentions: During this study, 218 sea turtles were observed on effort (2011: n = 79; 2012: n = 139) at a sighting rate of 0.01 turtles observed per km surveyed (Table 1). Four species (80% of all observations) were sighted and identified to species: loggerheads (Caretta caretta), green turtles (Chelonia mydas), leatherbacks (Dermochelys coriacea), and Kemp’s ridleys (Lepidochelys kempii). Spatial distributions of sea turtle sightings revealed that 72.8% of observations (n = 158) occurred within 20 km of the shoreline, west of the estimated core of the Florida Current (Fig 2). The most frequently observed species in our study was the loggerhead turtle (n = 113; 52% of all observations) followed by the green turtle (n = 57, 26%). Distributions for both species were similar within our study area (Fig 3). Leatherbacks (1.8%, n = 4) and Kemp’s ridleys (<1%, n = 1) were rare. The low flight altitude allowed for confident identification of most turtles to species. The remaining 20% of sea turtle sightings (n = 43) could not be identified to species due to water clarity and distance from plane, but could be classified as cheloniids (hard-shelled species) and not as leatherbacks. Size classes recorded during the surveys indicated that small juvenile (n = 39), large juvenile (n = 116), and adult (n = 45) life stages were present in these waters.


Seasonal Variation in Sea Turtle Density and Abundance in the Southeast Florida Current and Surrounding Waters.

Bovery CM, Wyneken J - PLoS ONE (2015)

Sightings of the two most commonly observed sea turtle species in 2011–2012 by season.Loggerheads (top panels) and green turtles (bottom panels) sighted in each season during 2011–2012 aerial surveys. Note that the highest numbers of loggerheads sighted is in the spring while the highest numbers of green turtles sighted is in the summer. Each symbol represents a single sea turtle. Dotted lines represent the approximate location of the core of the Florida Current. Source: Florida Fish and Wildlife Conservation Commission-Fish and Wildlife Research Institute.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696830&req=5

pone.0145980.g003: Sightings of the two most commonly observed sea turtle species in 2011–2012 by season.Loggerheads (top panels) and green turtles (bottom panels) sighted in each season during 2011–2012 aerial surveys. Note that the highest numbers of loggerheads sighted is in the spring while the highest numbers of green turtles sighted is in the summer. Each symbol represents a single sea turtle. Dotted lines represent the approximate location of the core of the Florida Current. Source: Florida Fish and Wildlife Conservation Commission-Fish and Wildlife Research Institute.
Mentions: During this study, 218 sea turtles were observed on effort (2011: n = 79; 2012: n = 139) at a sighting rate of 0.01 turtles observed per km surveyed (Table 1). Four species (80% of all observations) were sighted and identified to species: loggerheads (Caretta caretta), green turtles (Chelonia mydas), leatherbacks (Dermochelys coriacea), and Kemp’s ridleys (Lepidochelys kempii). Spatial distributions of sea turtle sightings revealed that 72.8% of observations (n = 158) occurred within 20 km of the shoreline, west of the estimated core of the Florida Current (Fig 2). The most frequently observed species in our study was the loggerhead turtle (n = 113; 52% of all observations) followed by the green turtle (n = 57, 26%). Distributions for both species were similar within our study area (Fig 3). Leatherbacks (1.8%, n = 4) and Kemp’s ridleys (<1%, n = 1) were rare. The low flight altitude allowed for confident identification of most turtles to species. The remaining 20% of sea turtle sightings (n = 43) could not be identified to species due to water clarity and distance from plane, but could be classified as cheloniids (hard-shelled species) and not as leatherbacks. Size classes recorded during the surveys indicated that small juvenile (n = 39), large juvenile (n = 116), and adult (n = 45) life stages were present in these waters.

Bottom Line: This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current.Density of sea turtles observed within the study area ranged from 0.003 turtles km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012.This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, United States of America.

ABSTRACT
Assessment and management of sea turtle populations is often limited by a lack of available data pertaining to at-sea distributions at appropriate spatial and temporal resolutions. Assessing the spatial and temporal distributions of marine turtles in an open system poses both observational and analytical challenges due to the turtles' highly migratory nature. Surface counts of marine turtles in waters along the southern part of Florida's east coast were made in and adjacent to the southeast portion of the Florida Current using standard aerial surveys during 2011 and 2012 to assess their seasonal presence. This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current. While it is understood that marine turtles use these waters, here we evaluate seasonal variation in sea turtle abundance and density over two years. Density of sea turtles observed within the study area ranged from 0.003 turtles km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012. This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species.

Show MeSH
Related in: MedlinePlus