Virginia Coastal Program: 2004 Coastal Grant Project Description and Final Summary
Project Task:
FY2004 Task 11.03
Grantee:
Virginia Institute of Marine Science/Wachapreage Lab
Project Title:
Interactions Between Clam Aquaculture and Shorebird Foraging
Project Description as Proposed:
In the first two
years we identified areas of potential overlap between shorebird
concentrations and clam aquaculture, and we began to characterize
benthic prey for foraging shorebirds in areas with and without aquaculture.
During the periods when migratory shorebirds were present in the
region, we collected quantitative benthic samples from five intertidal
habitats in relation to clam aquaculture—(1) in the macroalgae
on top of the nets, (2) in sediments between the nets, (3) in sediments
at the location of old nets, (4) 50 – 100 m away from the nets
and (5) a site that had no history of clam aquaculture—for
the purpose of characterizing the species composition and abundance
of prey for shorebirds. Sample processing is still underway, but
preliminary results suggest that food resources for shorebirds vary
across these habitat types. During the next phase of this project
we will (1) complete the characterization of prey species and abundances
from the 2004 samples, (2) sample prey species during the summer
of 2005 to determine interannual variability, (3) obtain quantitative
data on shorebird foraging in areas with and without clam aquaculture
and (4) incorporate our findings on any effects of clam aquaculture
on shorebird foraging into the clam aquaculture BMP’s (Best
Management Practices) developed during Years 1 and 2 of the Seaside
Heritage Program.
We will collect quantitative data on foraging activity by shorebirds
in each of these habitat types. Observations will be made using
a spotting scope from a distance of at least 50 m during as many
low tides as possible over the period that shorebirds are present.
Observations at sites with clam aquaculture will be made both during
periods when clam farmers are present (tending nets, planting clams,
etc.) and not present to assess the effects of the farming activity
on shorebird foraging. Within pre-designated areas for which we
have characterized the benthic prey species, we will record the
number and species of shorebirds observed and quantify their time
spent foraging; within the clam aquaculture sites we will note whether
birds are feeding between the nets or on the nets.
Finally, we will integrate the findings from this work into the
developing BMP’s for clam aquaculture in an effort to minimize
the impacts of clam aquaculture on shorebird foraging.
Federal Funding:
$35,000
Project Contact:
Mark W Luckenbach, 757.787.5816; luck@vims.edu
Project Status:
Grant Closed
Final Product Received:
Project Summary Provided by Grantee:
Shorebird Prey and Clam Aquaculture Conflicts—Concern over the potential impact of predator exclusion nets used in clam aquaculture on foraging habitat and prey availability for migratory shorebirds was addressed by (1) examining the potential areas of overlap of the two uses and (2) the availability of benthic invertebrates that serve as prey for foraging shorebirds at sites with and without clam aquaculture. The results indicate that there is currently only limited overlap between primary shorebird foraging habitats and clam aquaculture sites. This finding is largely the result of the limited aerial exposure of the clam beds which are generally planted in the shallow subtidal and very low intertidal regions of mudflats. Surveys of benthic invertebrates which serve as prey for shorebirds were undertaken in the early summers of 2004 and 2006 at clam aquaculture and control sites. The findings from both years indicate that both species numbers and total prey abundance in the sediments on clam farms (both between the nets and at locations which previously had nets) are comparable to both local and distant control sites. Further, they reveal that the macroalgae (seaweed) on the surfaces of the nets harbor species numbers and prey abundances that are comparable to or even greater than those found in surface sediments on and off clam farms. These prey include a wide array of species generally considered to be infaunal, including many that are known prey items for shorebirds. In short, although the time available for shorebirds to forage at clam aquaculture sites is limited by tidal exposure, our data suggest that abundant and diverse prey are available at these sites.
Development of Environmental Codes of Practice and BMP’s for Clam Aquaculture—Environmental Codes of Practice (ECOP) and Best Management Practices (BMP’s) for clam aquaculture were developed with input from industry members and other stakeholders. The BMP’s have recently been updated to include the findings and recommendations from a survey of derelict clam netting conducted as another element in the Seaside Heritage Program and from the shorebird prey study referenced above. The BMP’s now incorporate elements related to site selection, site deliniation, predator protection, biofouling management, waste management, maintenance of water quality, disease management, exotic species, aesthetics and public education. The lack of a coherent industry organization within Virginia has impeded efforts to get full industry buy-in for the ECOP’s and BMP’s. These documents are expected to form the basis of an effort in the coming year to develop more broad-based ECOP’s and BMP’s for all shellfish culture in Virginia.
Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email: Laura.McKay@deq.virginia.gov
A more detailed Scope of Work for this project is available. Please direct your request for a copy to Virginia.Witmer@deq.virginia.gov
