Shellfish Research

Development of an ocean quahog recruitment index (shell aging)

Lead PI: Eric Powell (USM): Ocean quahogs (Arctica islandica) are extremely long lived. Although the NMFS-NEFSC survey time series began in 1980, most of the animals fished were borne prior to that time. Consequently, recruitment dynamics for this stock are very poorly understood. Establishing that the current fishery is sustainable requires information on the recruitment dynamics of ocean quahogs over the last 200 years. This can be reconstructed from the age frequency of the population. This project will develop the first age frequencies for ocean quahogs in the northwest Atlantic, with study sites off New Jersey, Long Island, Nantucket, and on Georges Bank.

Development of an Age-Frequency Distribution for Ocean Quahogs (Arctica islandica) on Georges Bank – Sara Pace, Journal of Shellfish Research

Evidence of Multidecadal Recruitment in the Ocean Quahog, Arctica Islandica in the Western Atlantic Ocean – Sara Pace, USM Master’s Thesis

Development of management options for surfclams

Lead PI: Eric Powell (USM). The recent benchmark assessment for surfclams considered a two-stock option for surfclams that was rejected by the Stock Assessment Review Committee. Nevertheless, the continued influence of Mid-Atlantic Bight warming on the distribution of the surfclam stock suggests that a range of management options may need to be reviewed. SCEMFIS will examine this issue and recommend options to the IAB.

SCEMFIS scientists identified management options that will increase LPUE and also increase stock productivity and stock abundance in the Mid-Atlantic region, while maintaining landings at present quota levels.

Generation of GIS layers for Nantucket and Georges Bank closed areas

Lead PIs: Eric Powell (USM) & Roger Mann (VIMS): Fishing has been restricted in two areas by the creation of Habitat Management Areas (HMAs), one off Nantucket Shoals (NS) and one on Georges Bank (GB). The SCEMFIS team will analyze NMFS survey data and data from the fishing fleet operating in the NS/GB region to provide improved differentiation between habitat of concern and high-energy sands supporting surfclam production. These analyses will provide information on subregions in the HMAs supporting live market-size surfclams and regions of complex habitat as evidenced by the presence of untowable bottom, location of reported dredge damage, and locations where the survey dredge caught cobbles, rocks, and boulders.

DATA:

  • GIS Data (zip), Layers(zip) and Files (.docx). Space delimited ASCII with self explantory headers. Each station represents the same area, given the domain of the survey (about 29.4 km2.) ASCII Data
Support of the Survey Design Working Group for the NMFS Clam Survey

Lead PI: Eric Powell (USM). This project will undertake a reappraisal of the clam quahog survey sampling design which has not previously been evaluated with respect to the relationship between sample number and stock patchiness. This issue is uniquely important for the entirety of the continental shelf benthic biota, not just the commercial clam species. Additional funding will also support for 2 members of the working group to attend meetings.

Report: Improving the NEFSC Clam Survey for Atlantic Surfclam and Ocean Quahog

61st Northeast Regional Stock Assessment Workshop (61st SAW) Assessment Report
(61NE_SAWclam_assessment) (NEFSC access to sections)

There is a new issue (CRD 17-10) of the Center Reference Document Series entitled 63rd Northeast Regional Stock Assessment Workshop (63rd SAW) Assessment Report, by the NEFSC

– R-package for survey design analysis – PC fileUnix file