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studies including comprehensive habitat characterization (Bestley et al., 2013), stable isotope analysis (Pajuelo et al., 2016) and fine-scale behavioural ecology (Okuyama et al., 2010; Watanabe & Takahashi, 2013) are needed to evaluate the extent to which other factors could be driving habitat selection and use by marine turtles in the region. This could provide further insights into the direct and indirect impacts of recreational fisheries on marine turtles. Understanding the interaction between anthropogenic
pressures and marine species is vital to inform local man- agement and conservation practices. Marine turtles in near- shore habitats reportedly tend to avoid areas with high human activity related to heavy boat traffic or intensive fish- ing (Renaud et al., 1995; Seminoff et al., 2002). The largest effect of the vessel–turtle interaction in Crystal River is probably related to the presence of a high number of vessels engaged in harvest activities. To reduce this effect, manage- ment measures could focus on number of vessel quotas al- lowed in any given area, or maintaining a minimum distance between boats (Norman, 2009). Another mitiga- tion strategy is the establishment of speed restrictions, such as go-slow zones (Calleson & Frohlich, 2007; DERM, 2008). Areas used by turtles in the study area are within zones that do not have speed regulations and/or the 40 km/h speed zone of the Manatee Protection Zone. Such speeds are probably too fast for turtles to avoid colli- sions. Green turtles have been reported to react to vessels when the boat speed is up to 4 km/h (Hazel et al., 2007). Although the area used by marine turtles is too large to be transformed entirely into a go-slow zone, slow speed areas could be expanded to include marine turtle hotspots. We recommend marine turtle behaviour should be considered in the planning of future management actions in coastal areas along the Eastern Gulf of Mexico. In conclusion, our study highlights the importance of considering recreational fisheries when assessing the spa- tial ecology of coastal marine turtle populations, even though the fishing practices in use might not pose an evi- dent imminent risk to the species. The cumulative and syn- ergistic exposure of marine turtles to direct and indirect pressures derived from recreational fisheries, in addition to other natural and atrophic threats, can have detrimental effects on the overall persistence of turtle populations (Fuentes et al., 2011; Maxwell et al., 2013). Further studies on seasonal effects on marine turtle behaviour and habitat use in the study area are needed. Such studies would bene- fit from more tracking data before, during and after the scallop harvest season. In addition, studies that quantify the response of marine turtles to the presence of vessels (e.g. using animal-borne technologies), and assess the medium- and long-term impact of the scallop and other recreational fisheries on the fitness and population dynam- ics of marine turtle populations would be informative for management purposes.
Acknowledgements
We appreciate the support provided by the Department of Environmental Protection of Florida, the Marine Turtle Research Ecology and Conservation Group at Florida State University, Inwater Research Group Inc., and the National Oceanic and Atmospheric Administration. This research was partly supported by the Florida Sea Turtle License Plate grant, and permitted by: National Marine Fisheries Service ESA Section 10(a) permit (#16733,#19496), Florida Fish and Wildlife Conservation Commission Marine Turtle Permit (MTP-16-30,MTP-16-243,MTP-17-243A), Research and Monitoring Special Use permit for Chassahowitzka (#41510-14002,#16011), and Florida Animal Care and Use Committee permit (ACUC #1524). We appreciate the critiques of the Editor and reviewers. All authors declare that there are no conflicts of interest.
Author contributions
MMPBF and CG designed the study, MMPBF, CG and CS carried out the fieldwork and NW carried out the analysis. NW and MMPBF wrote the manuscript, and CS and CG helped with editing and comments.
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Oryx, 2020, 54(3), 307–314 © 2018 Fauna & Flora International. This is a work of the U.S. Government and is not subject to copyright protection in the United States. doi:10.1017/S0030605318000182
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