Current research on the gear effects of crab dredging and clam raking in Raritan Bay is led by Clyde L. MacKenzie, Jr. of the Howard Marine Sciences Laboratory. Mackenzie is collecting samples to describe the effects of commercial bottom fisheries on the habitat as well as natural changes to the fauna.

Once a month the Nauvoo sails to survey the abundance of amphipod tubes of Raritan Bay in areas worked by crab dredges and clammers.

A Ponar grab is used at select stations to sample the bottom habitat.

Bottom samples collected by the grab reveal whether amphipod tubes are present, or not.
At times dense mats of amphipod tubes, of the genus Ampelisca cover the bottom.

The outlined study area is West and East of the US Navy’s Earle Pier. The survey has a total of 54 stations within this area. Between 15 and 36 stations are sampled every month. 

When the survey began in January 2007 the amphipod tubes were abundant throughout the study area. By mid to late summer the tubes had all but disappeared. However the December 2007 survey indicated a return of the tubes. This could indicate a natural cycle within the estuary.

In addition by observing the crab dredging effort stations are selected for sampling. In March 2007 a number of crab dredges worked in the study area. Grab samples revealed that the bottom was harder where dredging occurred and the amphipod tubes were gone. Further sampling will provide needed information on the recovery of the amphipods.

Contact: Clyde.MacKenzie@noaa.gov