Soft-shell clam recruitment monitoring network

In 2020, the Downeast Institute (DEI) and University of Maine at Machias (UMM) partnered with nine community shellfish programs Sipayik to Wells to establish the Soft-shell Clam Recruitment Monitoring Network. The network currently consists of 18 monitoring sites (two in each community) that measure densities of soft-shell clams recruiting to mudflats. Analysis of the amount of recruitment and recruit survival rate help to better understand local, regional, and coastwide trends in clam production. The Network standardizes clam recruitment data collection and begins to build a long-term database. The information generated from the monitoring network may inform new measures to better manage the soft-shell clam resource.

These are the major sites for the Soft-shell clam monitoring network. Image provided by Sara Randall at DEI.

The Network is based on a deep understanding of clam biology and ecology. Specifically, each of the 18 monitoring stations are composed of sixteen 1-ft x 2-ft x3-in deep wooden-framed “Beal Boxes,” which are deployed in the lower mid-intertidal gradient before the beginning of the clam spawning season. Small mesh on the top and bottom of the boxes protect the clams that settle into them from most predators. Protected from predators, clam recruits are able to survive and grow throughout the summer and fall. Scientists and community members retrieve the boxes in late October and early November (after clam settlement has ceased) and take 6-inch deep and 6-inch diameter samples of the adjacent mudflats in the late fall. The contents of the boxes and the samples  are processed through a 1mm mesh sieve and the number of recruits are counted and recorded. Determining the number of recruits inside the boxes shows us how many juvenile clams settled out during the season at that site. Comparing those numbers to the number per square foot and size distribution found in the samples from outside the boxes provides and understanding of  how many clam recruits are able to survive into adulthood at that location, providing information about how or why a clam flat is commercially productive. For more information on clam biology or ecology, please visit our Clam Ecology page

Primarily, the soft-shell clam monitoring network uses recruitment boxes to measure the productivity of clam flats. Image provided by Sara Randall, DEI.

The overarching goals of the Soft-Shell Clam Recruitment Monitoring Network are to: 1) Increase visibility and public awareness of a fishery that is threatened by a dramatically changing marine environment; 2) Create an extensive data set for shellfish managers to better understand factors that affect the fishery; and, 3) Encourage participation and learning by coastal residents including clammers, shellfish committee members, and other municipal officials as well as K-12 grade students, their teachers and parents. 


Dr. Brian Beal

Sara Randall

More information

Review the first technical report which details the results of baseline clam surveys at all 18 sites, which you can find here.