There are minimum sizes for shellfish under which size the shellfish must be immediately returned to the water and flats from which it came. This provides for the protection for the regeneration of the species.
The minimum sizes have been determined to enable the shell stock to be able to reproduce before being harvested.
How?
The inner width of the shellfish gauge measures 1 inch, which is the minimum size for harvestable quahogs
The inner length of the gauge measures 2 inches, the minimum size (on the longest length) for the taking of soft shell clams and blue mussels.