Browsing by Subject "Diamondback terrapins (Malaclemys terrapin)"

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    Sea Turtle Damage and Bycatch in North Carolina's Blue Crab Fishery
    (2006) Avissar, Naomi
    In 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.
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    Tracking terrapins through genetic analysis: Multilocus assignment tests shed light on origin of turtles sold in markets
    (2007) Lester, Lori A
    Diamondback terrapins (Malaclemys terrapin) are currently sold for human consumption in many large cities in the United States. Some Asian cultural groups utilize large numbers of terrapins, both regionally and world-wide, as a protein source. Terrapin populations face many prevalent problems including predation by both native and non-native predators, and anthropogenic disturbances (such as habitat destruction, roadkill, and bycatch in blue crab traps). The additional anthropogenic dilemma of terrapins sold in fish markets is particularly troubling when added to the long list of widespread disturbances. Terrapin harvesting is restricted in each state throughout the Atlantic and Gulf coastal range of the species; however, enforcement of these restrictions is weak. The objective of our study was to determine the origin of terrapins sold in New York City’s Fulton Fish Market. In 2004, we collected blood samples from 63 individual terrapins confiscated from illegal sellers in the Market. Some of these terrapins were released off the coast of Maryland, based on the belief that the terrapins were originally harvested in the Chesapeake Bay. In this study, we used microsatellite DNA variation to test the hypothesis that M. terrapin collected in the Market are from the Coastal Mid-Atlantic terrapin metapopulation. We extracted DNA from blood samples, performed PCR, and screened each turtle at 12 polymorphic microsatellite DNA loci developed for bog turtles (Glyptemys muhlenbergii). Statistical analyses relied on assignment tests to determine the most likely region of origin for each terrapin to the metapopulation and subpopulation level. Many of the terrapins were assigned to the Chesapeake Bay metapopulation (or subpopulations in Maryland); however, some terrapins were assigned to the Coastal Mid-Atlantic or the Coastal Carolina region. Rules and regulations (and the enforcement of these rules) need to be improved to adequately protect terrapins from direct harvest.