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Final Report: Survey of clam resources in the vicinity of the Hampton Roads Bridge Tunnel (I-64): Fall 2018
Mann, Roger Southworth, Melissa
Mann, Roger
Southworth, Melissa
Abstract
The Hampton Roads I-64 Bridge Tunnel (HRBT) is to be expanded. Hampton Roads has long supported a fishery for the hard clam (Mercenaria mercenaria). The last comprehensive survey of hard clam resources in Hampton Roads was completed by a joint effort of the Virginia Institute of Marine Science (VIMS) and the Virginia Marine Resources Commission (VMRC) in 2001-2002 when hard clams were present both upstream and downstream of the HRBT location. The Virginia Department of Transportation (VDOT), through Stantec, approached VIMS to perform a survey of current hard clam resources in the HRBT expansion project area. A field survey was completed on October 2018 in a swath extending 100m downstream and 200m upstream of the current HRBT for the entire length of the structure from Hampton at the western terminus to the eastern “over-water” limit at Willoughby Spit. A sampling grid was developed by the Repletion Program at VMRC based on a sampling density of one sample station per every 5 acres. Each sample was a one meter square collection with a hydraulic patent tong. A total of 110 samples were collected: 20 from Willoughby Bay, 34 from HRBT South (the southern approach to HRBT) and 56 from HRBT North. These three sampling regions have the following estimates of clam populations: clams are absent from 45 acres of Willoughby Spit, 67,854 clams are present on 186 acres of HRBT South, and 439,731 clams are present on 362 acres of HRBT North. Throughout the sampled regions clam densities were <0.3m-2 , comparable to or less than 2001-2002 clam densities for the same region and below that generally targeted by for commercial fishing (typically ~1.00 – 8.00 clams m-2). The observed 2018 clam densities and size distributions are not indicative of regular clam recruitment of any notable magnitude.
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2018-12-15
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Virginia Institute of Marine Science
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