U.S. Geological Survey Home Page USGS Patuxent Wildlife Research Center Science Meetings; dedicated to Chandler S. Robbins USGS Patuxent Wildlife Research Center; Science Meetings dedicated to Chandler S. Robbins Dedicated to Chan Robbins USGS Patuxent Wildlife Research Center; Science Meetings dedicated to Chandler S. Robbins Poster Abstracts from USGS Patuxent Wildlife Research Science Meetings, October, 2006
Patuxent Science Meeting 2006 Poster Abstract

Use of a traditional harvest method to sample diamondback terrapins in

winter in Chesapeake Bay

Haramis GM, Henry PFP, Day DD, Marshall D

Harvest of Diamondback Terrapins (Malaclemys terrapin terrapin) in Chesapeake Bay

historically took place in the winter months using dredges of various configurations. We worked

with Dwight Marshall, an experienced terrapin harvester from Smith Island to document these

methods first hand, to assess the effects of commercial harvest on local populations, and

potentially adapt the methods for scientific study. In winters 2003 through 2005, we used a

modified crab scrape to dredge 1220 terrapins at 7 hibernacula, 6 of which were located in the

Tangier Sound area. The scrape was framed with cold-rolled steel stock, was 1.7 m wide and

trailed an 8-cm mesh nylon bag to retain terrapins. The leading bar of the scrape was equipped

with 30 15-cm long downward facing teeth to help remove terrapins from soft bottom sediments.

Hibernacula were located in semi-protected estuarine bays normally within 300 m from nearby

marsh. These sites were characterized by water depths of 2 to 4 m and bottoms of moderately

soft mud. These conditions provided for good tidal circulation, even under ice cover, while at the

same time protecting against dewatering at extreme low storm tides. The cold winters of 2003

to 2005 (< 7 degree C February water temperatures) produced well-populated hibernacula of

virtually all adult terrapin. The dredge did not injure terrapins and proved to be an efficient

capture method capable of landing 200 terrapins/hr in some circumstances. We found terrapins

to be abundant at most sites and site-specific sex ratios to vary widely. Most importantly, our

sampling revealed the relative ease of harvest of large numbers of adult females from estuarine

bay hibernacula. Removal of large numbers of breeding age females could have long-term

effects on local terrapin populations.

Friday, September 22, 2006

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