R-06-01 Effect of bloodworm harvesting on tidal flat fauna and ecosystem function
William Ambrose, Jr.
Lewiston , ME 04240
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In Maine, many people make their living digging clams and worms from tidal mudflats. Commercial harvesting of blood worms alone is a $7.5 million dollar industry, with 269 metric tons of worms harvested in 2004. The effects of blood worm harvest on other species in the mudflat, and on the mudflat itself, are not known. In areas where clams and bloodworms live side by side, digging for bloodworms disturbs habitat and can injure or kill neighboring clams.
Ambrose and his colleague Curtis Bohlen documented patterns of bloodworm digging on heavily dug flats in midcoast Maine, using a combination of aerial photography and GIS to quantify the frequency and timing of digging. The study showed that bloodworm density on intertidal flats varies independently of harvesting pressure, and bloodworm size has not changed significantly over several decades, such that management now has a time-series basis for decisions. Bloodworm harvesting does not significantly increase clam mortality, so both species can be harvested on the same flat. A report will be issued to the Maine Department of Marine Resources detailing the patterns of habitat use by bloodworm harvesters and a time-series of baseline data on bloodworm abundance and size. This project received continued funding from Sea Grant in 2008.
2-year project, 2006-2008