Browsing by Subject "Loggerhead sea turtle (Caretta caretta)"
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Item Open Access AN EVALUATION OF NEST RELOCATION AS A LOGGERHEAD SEA TURTLE (Caretta caretta) MANAGEMENT TECHNIQUE IN NORTH CAROLINA(2003) Rush, Matthew DA network of volunteers, under the guidance of the North Carolina Sea Turtle Protection Program, monitors and protects loggerhead nests laid on state beaches. Although volunteers are encouraged to allow nest incubation to proceed naturally and with minimal intervention, some volunteers will relocate freshly laid nests that are threatened by possible inundation by high tides, heavy beach traffic, or under a sloughing escarpment. Nest relocation may have negative effects: it may reduce hatching success, alter incubation duration, and reduce hatchling fitness. Thus an evaluation of hatching success and incubation duration at nesting areas under the protection of the NC Sea Turtle Protection Program is warranted. My objective for the evaluation was to use loggerhead sea turtle (Caretta caretta) nest activity data from four high-density North Carolina nesting areas – Bald Head Island, Cape Lookout National Seashore, Cape Hatteras National Seashore, and Topsail Island – to assess statistically the management technique of nest relocation in North Carolina. Using 1997 to 2001 data, provided by the North Carolina Sea Turtle Protection Program, I evaluated hatching success and incubation duration among in-situ nests, relocated nests, and in-situ nests affected by tidal inundation. During each of the five years, 1997 to 2001, the average number of nests moved on the study’s four North Carolina nesting areas approached 40 to 60 percent. The evaluation of hatching success showed a tendency of more loggerhead hatchlings hatching in in-situ nests than in relocated nests. Also, the evaluation indicated a tendency of in-situ nests having longer incubation durations than relocated nests. The evaluation showed relocated nests might have shorter incubation periods, and thus present nest relocation techniques in North Carolina might be skewing northern sub-population sexratios more in favor of female hatchling production. I formulated a series of nest relocation recommendations with the evaluation results: use nest relocation as a last resort, only relocate nests that will be over-washed daily by high tides, do not base nest relocation measures on previous summer storms, and do not relocate nests in heavy foot traffic areas.Item Open Access REDUCING SEA TURTLE DAMAGE TO CRAB POTS USING A LOW-PROFILE POT DESIGN IN CORE SOUND, NORTH CAROLINA(2002) Marsh, Jesse C.The blue crab (Callinectes sapidus) supports North Carolina's most valuable commercial fishery; the value of hard blue crabs landed in 2000 was over $30 million dollars. This lucrative fishery may be adversely affected by loggerhead sea turtles (Caretta caretta), which are listed as threatened under the Endangered Species Act of 1973. Crabbers in Core Sound, North Carolina, report that sea turtle damage to crab pots has become an increasingly serious issue. Turtles damage crab pots by overturning them while trying to get the bait, tearing up the bottoms and sides of the pots; this damage results in higher gear replacement costs and losses in crab catch. Experimental fishing was conducted to test for differences in crab catch and pot damage using three types of crab pots: low-profile, square mesh, and hexagonal mesh. The hexagonal mesh pot is the most common pot type used by crabbers in Core Sound, and the low-profile pot was designed to reduce the sea turtles' ability to overturn the pots. The number and size of all crabs caught in the experimental pots were recorded. An analysis of variance (ANDVA) was used to analyze the relationship between number of crabs caught per pot and the effect of pot type, location, date, the interaction of date and location, and the interaction of pot type and location. Tukey-Kramer multiple comparison tests were used to determine significant differences among treatments. There was no significant difference in crab catch between the low-profile and the square mesh pots at any of the three experimental fishing locations. There was a significant difference in catch between the low-profile and hexagonal mesh pots at one location. The lowprofile pots sustained considerably less damage than both the square mesh and hexagonal mesh pot types. In interviews with 19 Core and Pamlico Sound crabbers, crabbers estimated that 62% of all crab pot damage, and 37% of lost crab catch, is due to sea turtle damage. The low-profile crab pot has the potential to improve this situation by allowing crabbers to maintain crab catch with a reduction in gear replacement costs.Item Open Access Sea Turtle Damage and Bycatch in North Carolina's Blue Crab Fishery(2006) Avissar, NaomiIn North Carolina’s sounds, loggerhead sea turtles are causing significant economic problems for blue crab fishermen by damaging crab pots, stealing bait, and reducing crab catch. This may be causing the fishermen to change their fishing locations, moving their crab pots further towards shore where they potentially encounter more bycatch of species that tend to be found near shore, such as diamondback terrapins. Loggerheads are a federally threatened species, and most of the loggerheads that interact with crab pots in North Carolina’s sounds are large juveniles, one of the most sensitive stages of their life cycle (Crouse et al. 1987). To exacerbate the problem, the state’s blue crab fishery is threatened by pollution, nitrification, and overfishing, and is listed in the “concern” category by the NC Division of Marine Fisheries. The loggerhead-fishery conflict could worsen as blue crabs are depleted, because turtles and fishermen that are drawn to the same prey may aggregate in smaller patches of crab availability, increasing probability of overlap. Due to these issues, and those associated with bycatch, careful management of the blue crab resource and the turtle interaction in the fishery is crucial. I conducted a collaborative fishing study with commercial crabbers to characterize location, timing, and extent of sea turtle damage to their crab pots, and tracked crab catch and bycatch in each pot. I examined spatial and temporal overlaps of crabbing with sea turtles and bycatch, and documented turtle-damage hotspots. Though over 990 animals were captured as bycatch, no clear spatial pattern was detected. My results may guide crabbers to times and areas of minimal overlap, where they should concentrate their fishing effort to minimize economic and ecological damages. This document describes the results of this research, and provides ecological, economic, and political analysis of the conflict.Item Open Access USING SURVEYS AS A TOOL TO ASSESS SEA TURTLE DISTRIBUTION AND HABITAT USE, AND TO PROMOTE PUBLIC ENGAGEMENT IN ENDANGERED SPECIES RESEARCH AND MANAGEMENT(2007-05) Saladin, NicoleFemale loggerhead sea turtles nesting on Bald Head Island, N.C. were equipped with satellite transmitters to assess their post-nesting movements and habitat use. The resulting surface satellite data revealed foraging and overwintering sites used by these sea turtles, but data provide limited benthic habitat information. To complement this data, a survey was developed to target N.C. dive shops, fishermen and offshore researchers to gather information in an effort to characterize the features of these habitats. An online survey and database will allow for public reporting of sea turtle sightings data and habitat information to complement existing long-term observation studies. By engaging the public in this citizen-scientist approach to sea turtle monitoring, these efforts may promote state-wide awareness and conservation efforts for sea turtles, as well as provide valuable data to researchers. The survey will eventually be expanded to accommodate global sightings reports and data will be managed through regional networks.