Shellfish Dredge Survey
Hydraulic dredge
Deploying the dredge
Emptying the dredge
Measuring clams
Measuring clams
Background
The RI shellfish dredge survey aims to understand the relative abundance and distribution of quahog clams within Narragansett Bay. The data collected is used in stock assessments, development of Fishery Management Plans, and to characterize and map essential quahog habitat within the bay. The survey has been conducted since 1993 and will continue to collect biological information to help inform stock assessments and shellfish management actions such as quahog transplants and permit review.
Survey Design
The survey encompasses the upper Narragansett Bay. The region is split into stratums and each stratum is sampled biannually. The exception being Greenwich Bay and the Providence River which are sampled annually.
Survey Gear
The survey uses a hydraulic dredge with an 18-inch width which is towed from a vessel. The dredge is equipped with a 1-inch mesh to ensure all legal sized quahogs are retained.
Sampling Methods
A hydraulic dredge is towed behind the Reliance RV (36’ Calvin Beal) for a length of 100 feet within each station. All quahogs are counted and measured (hinge width in mm). Bycatch species are identified and enumerated. Details about the trip are recorded, such as date, sediment type, and position (latitude and longitude).
Sampling Frequency
Each dredging location in the bay is sampled biannually, except for Greenwich Bay and the Providence River, which are sampled every year.
For more information about the survey please contact Patrick Barrett.