<p>Sea turtles, marine mammals and sea birds are vulnerable to higher mortality rates as a direct function of incidental capture (bycatch) in marine fisheries. Their migratory behavior exposes them to multiple fishing gear types and fishing practices and efforts to understand the rates of interaction between these taxa and fishing necessarily entails analysis of data over large spatial areas (ocean-basin) and multiple types of fishing activities. The acquisition the requisite data, however, requires considerable resources and many regions in the world are data-poor with respect to bycatch, including the Wider Caribbean Region (WCR) in the west central Atlantic Ocean basin. This dissertation presents the results of multiple strategies used to assess sea turtle, marine mammal and seabird bycatch in the WCR, with a particular focus on sea turtle bycatch. The research incorporated a synthetic review of the literature, expert consultation, statistical techniques, and geospatial analyses to assess the bycatch seascape for the region. I conclude that sea turtle bycatch in the WRC is significantly linked to turtle rookeries, especially those on the continental land mass and in the southern section of the Caribbean basin, in large part because of the near shore artisanal nature of the fisheries and the importance of these habitats for foraging and reproduction. The limited information on marine mammal bycatch does not permit robust inferences, but it clearly identifies threats to at least one vulnerable marine mammal species, the tucuxi (Sotalia fluviatilis). Information on seabird bycatch was even more limited; the most vulnerable seabird populations occur in the higher latitudes (temperate zones) while the seabird populations in the WCR face significant threats from habitat loss and over-exploitation. This dissertation proposes specific recommendations for improving and advancing the information base for a regional, ecosystem-level management and mitigation of bycatch.</p> / Dissertation

This study evaluated how three conservation approaches implemented by the Brazilian Sea Turtle Conservation Program (the TAMAR Project) are related to local support for sea turtle conservation in Praia do Forte, Brazil. Four species of sea turtles nest in Praia do Forte. In Praia do Forte, locals harvested sea turtles for their meat and eggs on a regular basis to support subsistence needs. The three conservation strategies analyzed are employment opportunities and alternative sources of income from sea turtle ecotourism; enforcement of federal sea turtle protection laws; and implementation of environmental education programs via sea turtle ecotourism. These conservation strategies, which are implemented since 1982, represent both top-down and bottom-up conservation paradigms. Qualitative and quantitative data were gathered through nine months of fieldbased research (between May 2006 and September 2008), using tools of participant observation, semi-structured interviews, and key informant interviews. Results indicate that conservation strategies implemented by TAMAR seem to influence local support for sea turtle conservation. Income and environmental education programs to the local children are cited as the main benefits sea turtle conservation brings to the community. Enforcement caused resentment when first implemented, but is now perceived as a necessary strategy to protect sea turtles. The relative lack of community participation in sea turtle conservation seems not to have hampered local support for sea turtle conservation. In fact, the majority of respondents perceive TAMAR as the most appropriate entity to manage sea turtles, and only a minority believes the community should co-manage sea turtle conservation with TAMAR. Though these three conservation strategies seem to help maintain traditional ecological knowledge, the future of this knowledge across generations is uncertain. Though community-based sea turtle conservation is working at the community scale, external factors associated with tourism development at the larger scale seem to influence both livelihoods and sea turtle survival. On a negative side, larger scale tourism development is associated with an increase in the cost of living, the introduction of drugs, violence and greater sense of insecurity, changes in the local fishing culture, and with ongoing threats to sea turtle survival. Tourism development is associated with benefits as well, including improvements in the local infrastructure, employment opportunities, and alternative sources of income. Since tourism development, at both local and regional scales, is unlikely to decrease any time soon, sea turtle survival no longer solely depends in getting local support for sea turtle conservation, but also in addressing the external factors that drive conservation and consumption of sea turtles. Overall, sea turtle ecotourism is one part of a larger strategy for meeting local socioeconomic needs while also protecting sea turtles in Praia do Forte.

The nesting demographics of sea turtles using beaches within the Barrow, Lowendal, Montebello (B-L-M) island complex on the North West Shelf of Western Australia were examined in the context of their spatial and temporal distribution and potential for exposure to industrially based artificial light sources. The distribution of overnight turtle tracks throughout the island complex confirmed high density nesting of Chelonia mydas (green turtles) on deep, sandy and high energy beaches and Natator depressus (flatback turtles) on deep, sandy and low energy beaches, while Eretmochelys imbricata (hawksbill turtle) tracks were most visible on shallow, sandy beaches adjacent to near shore coral reef habitat. The three species exhibited a summer nesting peak. Hawksbill turtles commenced nesting in September and continued through to January, green turtles commenced in November and decreased in March. Flatback turtles displayed the most constrained nesting season reported to date in Australia with 86% of the animals visits recorded in December and January only. Nesting population sizes estimated for the three species suggest that on a national scale the B-L-M complex is a moderately large green turtle and a large flatback rookery site. The hawksbill rookery is large on an international scale. While none of the green turtle nesting beaches fell within a 1.5 km radius of industrially based artificial light sources an estimated 42% of nesting flatback turtles and 12% of nesting hawksbill turtles were potentially exposed to these light sources. Testing of green turtle and hawksbill hatchling response to different wavelengths of light indicate that hatchlings from the B-L-M region respond to low wavelength much like hatchlings tested in North America (Witherington 1992a). Flatback hatchlings displayed a similar preference for low wavelength light however their responses to discrete light wavelengths between 400 nm and 700 nm suggest that this species may not discriminate well between wavelengths that lie between 450 nm and 550 nm. This response may be related to the rapid attenuation of visible light that occurs in the turbid near shore habitats favoured by this species. Field based arena studies carried out to investigate hatchling behaviour on nesting beaches with light types commonly used in industrial settings found green turtle and flatback hatchlings are significantly attracted to these lights compared to controls. Lights that emit strongly in the low wavelength range (i.e. metal halide and fluorescent) caused hatchling misorientation at lower intensities than the test light that emitted relatively poorly in this range (high pressure sodium vapour). Hawksbill hatchlings tested in situ under the influence of actual oil and gas onshore and offshore facility based lighting were disrupted from the most direct line to the ocean by these light emissions. Emergence fan mapping methods that measure hatchling orientation on nesting beaches were refined and are proposed as an alternative monitoring tool for use on beaches that are logistically difficult to access for large scale experimental orientation studies. The hatchling behaviour was clearly complicated by beach topography and moon phase. Satellite tracking of post nesting female green and hawksbill turtles from North West Shelf rookeries has identified the Western Australian location of migratory corridors and foraging grounds for these species while Scott Reef turtles migrate from their south Timor Sea rookery to Northern Territory waters. Green turtle nesting on Barrow Island and Sandy Island (Scott Reef) forage at feeding grounds 200 – 1000 km from their nesting beaches. Hawksbill turtles nesting at Varanus Island and Rosemary Islands forage at locations 50 – 450 km from their nesting beaches. While all of the nesting beaches within the B-L-M island complex are protected under the Barrow-Montebello Marine Conservation Reserves, the only foraging ground similarly protected is the Northern Territory foraging ground used by Scott Reef green turtles. None of the foraging grounds used by North West Shelf green or hawksbill turtles is currently protected by conservation reserves.

No description available.

Beach nourishment has become common in Florida and it occurs on beaches that are major loggerhead (Caretta caretta) nesting grounds. Despite efforts to use beach-quality sand, nourishment sand may be different in grain size, moisture content, shear resistance and temperature when compared to native sand. Two main aspects of loggerhead nesting may be affected by nourishment. First, nourishment may reduce nesting success [(female nesting emergences/ female total emergences) X 100] due to physical barriers (i.e., scarps or steep cliffs) that can impede gravid females. Second, nourishment may reduce reproductive success {i.e., hatching success) by altering the nestsand environment. The objective of this study was to compare loggerhead nesting success, nest placement, slopes at nest sites, nest depths, incubation periods, reproductive success and egg fates among an old renourished beach {"south"), a recently nourished beach ("treatment") and a natural beach ("control") at Sebastian Inlet, Florida in 1996, 1997 and 1998. In all three years, nesting success was significantly different among study sites. After nourishment (1997), nesting success was reduced at the treatment site due to a seaward scarp. A year later (1998), the scarp was leveled and nesting success improved. Nest placement was not significantly different between study sites prior to nourishm_ent of the treatment study site (1996), but it was after nourishment (1997) and one-year post-nourishment (1998). After nourishment, most nests at the treatment beach were placed too close to the water or too close to the dune. There were no significant differences in the slope at nest sites in 1997; suggesting females may have selected similar increases in slope, but at varied cross-shore locations. Nest depths were significantly shallower at the treatment beach after nourishment, probably due to higher compaction of the nourishment sand. In addition, incubation periods were significantly longer on the nourished beaches one year post-nourishment. Loggerhead hatching success was significantly reduced on the nourished beaches in 1996 and 1997. The reduction was seen primarily in a larger proportion of eggs that were arrested early in development. The higher moisture in the nourishment sand may have impeded gas exchange, which resulted in decreased hatching success. One year post-nourishment (1998), there were no significant differences in hatching success. The lack of rainfall in 1998 may have introduced better incubation conditions on the nourished beaches. Researchers at the Florida Institute of Technology continued to show that the nourishment sand exhibited significantly smaller grain size, higher moisture content, lower temperature and higher shear resistance. These attributes were probably responsible for many of the results reported herein. However, other variables such as non-random nest depredation, inlet influences and water table levels may have also contributed to the results.

The cues used by marine turtles to locate foraging areas in the open ocean are largely unknown though some species (especially the green turtle [Chelonia mydas], the loggerhead [Caretta caretta], and the leatherback [Dermochelys coriacea]) somehow locate areas of high productivity. Loggerheads can detect airborne odors, but a capacity to orient has not yet been investigated. In this comparative study, tethered loggerheads and leatherbacks were exposed to dimethyl sulfide (DMS) or food odors in a laminar flow of air. Turtles did not orient into the air current. Free-swimming loggerheads and green turtles were also exposed to air- or waterborne food (squid) odor plus a neutral visual stimulus. Both species showed increases in swimming activity and biting behavior to both stimuli. These results suggest that airborne odors are likely not used to locate distant areas, but that they are used in localized food searching efforts. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

There are four distinct subpopulations of loggerhead sea turtles (Caretta caretta) in Florida as determined behaviorally by geographic fidelity, and genetically by mitochondrial haplotypes. The South Florida subpopulation consists of females nesting on the southeastern and southwestern coasts of Florida and their offspring. Previous research shows that west coast hatchlings exhibit higher levels of nocturnal swimming during the postfrenzy period than east coast hatchlings. This study attempted to determine how these differences in migratory behavior develop. A reciprocal translocation experiment was conducted to distinguish between environmental and genetic factors. No consistent differences in hatchling swimming behavior were seen based on geography. Movement of nests resulted in lower levels of nocturnal swimming behavior in hatchlings compared to hatchlings that emerged from natural nests, suggesting that the relocation of nests may not provide a natural incubation environment for developing hatchlings. / by Jeffrey Guertin. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Loggerhead sea turtles nest on either the Atlantic or Gulf coast of Florida. The hatchlings from these nests migrate offshore in opposite directions. The purpose of my study was to determine if Gulf coast hatchlings use magnetic maps, as Atlantic coast hatchlings do, both to locate areas favorable for survival in the Gulf of Mexico and to orient appropriately within surface currents that could transport them into the Atlantic Ocean. To find out, I presented Gulf coast hatchlings with magnetic fields corresponding to different locations inside the Gulf, and within currents leading into (Florida Straits) and within (Gulf Stream) the western portion of the Atlantic Ocean. I conclude that Gulf coast hatchlings (i) use a high resolution magnetic map for navigation within the Gulf of Mexico, (ii) initially remain within the eastern Gulf, but later may (iii) gain entry into currents that transport them into Atlantic waters. / by Maria W. Merrill. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Worldwide, sea turtles are especially vulnerable immediately after emerging from nests. Many monitoring programs measure hatchling production from nest inventories. These inventories rarely account for mortality occurring post-emergence, leaving an incomplete estimate of hatchling production. This study addresses the nest-to-surf data gap for Florida’s east coast nesting assemblages of loggerhead sea turtles (Caretta caretta). Five locations were surveyed during the 2016 nesting season by using infrared time-lapse imagery, night vision optics, and track maps. Over all beaches, 7.6% of the observed hatchlings did not survive to reach the water. Mortality sources varied by location. Observed predators included: foxes, bobcats, yellow-crowned night herons, ghost crabs, and gulls. Hatchling disorientation and misorientation occurred more frequently in urban areas than natural areas. Factors including number of hatchlings emerging, nest-to-surf distance, and urbanization may help managers estimate nest-to-surf mortality. This study will improve life history models that serve as foundations of conservation management. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy