DEI has been working with towns in eastern Maine since 1987 when we were known as the Beals Island Regional Shellfish Hatchery. Our work continues today as we transfer knowledge and technology necessary to adapt the soft-shell clam fishery to the effects of environmental change, specifically problems associated with increased levels of predation by invasive green crabs and other predators.

DEI’s recent investigations into the cause of the southern Maine clam decline identified extremely high levels of predation (over 99% of clam recruits dying within their first year) driven by warming ocean temperatures, to be the cause of the dramatic decreases in commercial clam populations. Though the waters of eastern Maine are generally cooler than the waters of southern Maine, DEI’s long-term research data set research shows that the region is not immune to the effects of rising predation.

For example, DEI and the University of Maine at Machias have been conducting clam growth and survival experiments since 1999 at Duck Brook Cove in Cutler. Our research shows that:

1) Clam survival dropped from an average of 58% from 1999-2007 to only 32% clam survival from 2008-2014.

2) The first year that clam survival dropped dramatically, 2008, was the same year that significant amounts of juvenile green crabs were found in our experimental units. Prior to 2007  green crabs were rarely seen in our experiments.

Average clam survival vs percent of experimental units containing green crabs at Duck Brook Flat, Cutler, ME from 1999 to 2013.

To help clammers in local communities measure the effectiveness of predator deterrents and other conservation strategies to help sustain the fishery, DEI  worked with the towns of Gouldsboro, Steuben, Milbridge, Addison, Machiasport, Perry, Pembroke, Trescott and Edmunds to initiate a Community Clam project. With DEI’s assistance, clammers and others:

1) Deploy, monitor, sample and assess the effectiveness of predator deterrent netting on clam survival and growth in areas seeded with hatchery-reared clams at one or more location within each town.

2) Measure rates of wild clam recruitment and compare survival and growth of cultured clams at two flats in the town. This effort helps inform of best places to deploy nets the following year.

2017 Results

The video below shows the 2017 results as presented at the 2018 Fishermen’s Forum.

Click here to see the 2017 results.

The information produced from this project informs helps the members of the municipal Shellfish Committees to better understand their resource and managing it effectively. It gives Committees the tools and skills needed to evaluate the potential natural productivity of flats, implement predator exclusion techniques, and monitor results in terms of clam survival and growth. It transfers the technology and skills to the clammers themselves so that they understand which management efforts have the greatest return on the investment of time and resources.

2018 Results

 

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