Bovery, Caitlin M.

Assessing the presence or absence of marine turtles in an open system poses both
observational and analytical challenges due to the migratory nature of marine turtles and their
use of large current systems. Concentrations can shift as turtles shift between oceanic and neritic
stages and migrate between breeding and foraging grounds. We conducted standard aerial
surveys monthly from 2011-2012 to capture seasonal snapshots of sea turtle presence. Each
survey covered the area from a northern boundary near West Palm Beach, Florida
26°43′N to a southern boundary near Miami, Florida 25°40′N, USA with
transects up to 20-50 km offshore. 218 turtles were observed during the course of this study
2011: n 79; 2012: n 139. We summarize our sightings by season: Winter December-February,
Spring March-May, Summer June-August, and Fall September-November to examine trends in
presence of sea turtles. A variety of sizes were observed throughout the year, indicating the
presence of several life stages of marine turtles in Florida’s waters during all four seasons. While
it is understood that marine turtles use the waters off the eastern coast of Florida, here we
document the magnitude of the shift in turtle presence each season throughout two years and
where the turtles occur most frequently. Our assessment of marine turtles in the waters off of
southeast Florida provide valuable metrics describing the in-water biology of these turtles and
for the first time, provide a quantitative assessment of annual and inter-annual fluctuations in
presence in the major current and along our coast.

Assessing the spatial and temporal distributions of marine turtles in an open
system poses both observational and analytical challenges due to their migratory nature
and use of large current systems. Concentrations of animals can shift because turtles
undergo large-scale migrations and habitat shifts seasonally as well as a function of lifestage.
Surface counts of marine turtles in waters off Florida’s east coast were made in
and adjacent to the Florida Current using standard aerial surveys. While it is understood
that marine turtles use waters off the eastern coast of Florida, here we document the
magnitude of the shift in turtle presence each season throughout a two year study and
identify habitat characteristics where turtles occur most frequently. Our assessment of
marine turtles in the waters off southeast Florida provide valuable metrics describing the
in-water biology of sea turtles in this area to inform future management strategies of
these endangered species.