The precautionary shellfish harvesting closure announced last week for Narragansett Bay, Mt. Hope Bay, Kickemuit River, Sakonnet River and their tributaries remains in effect until further notice. The Rhode Island Department of Environmental Management (DEM) announced today water samples collected on Sunday, October 9 still show high levels of phytoplankton in the Bay. DEM and the Rhode Island Department of Health (RIDOH) will continue to monitor water quality and shellfish meats to determine when these local waters can be reopened to shellfishing.
DEM regularly monitors local waters for the presence of phytoplankton that can produce harmful algae blooms. Since the closure, water samples are being taken every other day. Until Bay samples indicate the bloom is declining, efforts to collect local shellfish for analysis to determine if the toxins are present in shellfish meats at levels of concern will be suspended. The toxin, known as domoic acid, produced by these phytoplankton is responsible for causing amnesiac shellfish poisoning (ASP) in humans. Symptoms of ASP include short- and long-term memory loss along with other serious health effects.
Samples collected on October 9 from four of the coastal salt ponds show that Pseudo-nitzschia cells were absent or present at very low levels. The ponds sampled include – Winnapaug Pond, Pt. Judith Pond, Quonochontaug Pond, and Ninigret Pond.
Today’s sampling efforts focused on offshore waters outside the mouth of the Bay and waters flowing into Ninigret, Winnapaug, Quonochontaug and Pt Judith Pond.
Shellfish meats were collected by DEM from Narragansett Bay and aquaculture areas in southern Rhode Island coastal ponds over the weekend. The samples were transported to Maine for analysis. Test results confirm no toxin was present. As a result, RIDOH has released the inventory of shellfish collected last week, which were being held by dealers since the ban was enacted on October 6.
The shellfish closures, enacted at sunrise on Friday, October 7 and Saturday, October 8 are due to a confirmed harmful algae bloom (HAB) caused by the presence of toxic phytoplankton, Pseudo-nitzschia spp. The harvest restriction does not apply to carnivorous snails, such as whelk and moon snails.
Given the high concentrations of phytoplankton in several areas of Narragansett Bay and the confirmed presence of toxins in the phytoplankton, and out of an abundance of caution, all portions of the Bay where these elevated levels were found were closed to shellfish harvesting until further notice. There is no evidence that southern Rhode Island coastal ponds have been affected by the HAB.
For updates on shellfish closure areas, contact the DEM 24-hour shellfishing hotline at 401-222-2900.