Shellfish Closures Status & Trends

Related Pages:   B120 Shellfish Oil Spill Closures    Red Tide Closures

The maps below show pollution related shellfish resource area closures and status in Buzzards Bay projected for July 1, 2024 (top) and compared to July 1, 2023 (bottom). Theses maps does not include resource area management closures for seeded areas, shellfish relay area closures, or temporary rainfall related closures (either local rainfall conditionals or bay-wide closures related to extreme rainfalls). Permanent closures are areas closed year-round. Temporary closures are generally “seasonal closures”, that is, areas closed typically between June and September, but in some areas, closures may extend from April to November, or longer. The dramatic increase in permanently closed areas south of New Bedford, and the new expansive conditional closure area (shaded blue) stretch from the Westport-Dartmouth border to the Town of Marion, to Woods Hole and the Elzabeth Islands was the result of the Massachusetts Division of Marine Fisheries (DMF), complying with Food and Drug Administration rules issued about 2018. As noted on this Mass.gov webpage, DMF is required to meet National Shellfish Sanitation Program (NSSP) requirements when classifying shellfish growing areas, particularly around wastewater treatment facility outfalls.  The rules require closed safety zones around wastewater facility discharges based on specific model dilution concentrations. Massachusetts is a member of the Interstate Shellfish Sanitation Conference (a state-industry-FDA partnership), and state law and regulations require that DMF follow the NSSP when classifying shellfish growing areas. Failure to comply with the NSSP rules could result in significant sanctions on Massachusetts’ interstate shipping of shellfish. The new closure lines were based on a November 15, 2023, study by UMass Dartmouth and the Division of Marine Fisheries that identified a 1;500 dilution zone (approximately the new prohibited (shaded red south of New Bedford in the 2024 map) areas, and a 1:1000 dilution zone area (shaded blue in the 2024 map).

As shown in the next figure, the acreage of shellfish beds closed on July 1 in Buzzards Bay declined between 1994 and 2017. Increasing shellfish bed closures during the 1970s and 1980s was one of the principal drivers for the establishment of the Buzzards Bay National Estuary Program, and closures on July 1st was one of the indicators used by the NEP to track success in meeting goals of the Buzzards Bay Comprehensive Conservation and Management Plan, and by the Buzzards Bay Coalition in their state of Buzzards Bay reports. This figure does not include the Bouchard Oil spill shellfish bed closures.

Credit: Much of the information on this page was based on data kindly provided by the Massachusetts Division of Marine Fisheries which was analyzed by the BBNEP to prepare the maps and charts on this page. Note that all of Buzzards Bay is carved into “shellfish resource areas”, but only portions of these resource areas may have commercially or recreationally viable “shellfish beds.”

2015 Closure Boundaries

Caution: This map is superseded by maps posted at town hall or notices posted at the shoreline

Brief history of shellfish bed closures in Buzzards Bay

Throughout the 60s, 70s, and 80s, shellfish beds were increasingly being closed in Buzzards Bay due to fecal coliform contamination. As a result, keeping shellfish beds open and reopening closed beds were among the highest priorities contained in the Buzzards Bay Comprehensive Conservation and Management Plan when it was drafted in 1990. The reopening of shellfsih beds during the 1990s and 2000s were the result of the State Division of Marine Fisheries (DMF) and municipalities working together together to identify and remediate pollution sources. The opening of shellfish beds in Buzzards Bay resulted from two factors: water quality improvements and in implementing rainfall “conditional closure” programs.

Several important events and trends occurred during this period. As a result of the April 2003, the Bouchard No. 120 closed large areas of Buzzards Bay to shellfish, and some areas of Buzzards Bay (approximately 231 acres) remain closed through 2005 (figure below). Go to our Bouchard No. 120 Shellfish bed closure page for more info. Between 1990 and 2010, the Division of Marine Fisheries reduced the geographic extent of shellfish bed closures in some estuaries to a zone around certain stormwater discharge pipes. This is illustrated by the map of closures in Buttermilk Bay below. Another important trend is that the duration of “seasonal closures” has been lengthened in many areas. Ten to twenty years ago, seasonal closures typical lasted June 1 through September 1 (or Memorial Day to Labor Day). In recent years, these closures have extended, with some closures beginning May or April, and ending October or November. This means that although the closures on July 1 have been relatively unchanged during the past few years (except for the oil spill closures), the actual acre-days of shellfish closures has increased. However, this trend has been outpaced by the total summer season closures in Buzzards Bay as per the figure below.

The expansion of the summer seasonal closures was due the extended duration of degraded warm water conditions. This decline in water quality in some cases relates to increased development near shore, increased year-round occupancy rates in some coastal vacation communities, warmer weather, and even extended occupation of harbors by waterfowl due to delayed migrations.

Changes in Buttermilk Bay shellfish bed closures

Comparison of Shellfish bed closures in 2001 versus 2006. The seasonal area in Little Buttermilk Bay was eliminated and reclassified to approved with the exception of two small prohibited areas on April 14, 2003. The prohibited area in Queen Sewell Cove and the conditional area at Hideaway Village were both reclassified to approved with the exception of the current small prohibited classifications in both areas on October 17, 2001. Go to our Buttermilk Bay Stormwater Project page to learn more of what happened here.

Current shellfish bed closures in Buzzards Bay

This chart shows the annual status of pollution related shellfish resource area closures in Buzzards Bay as of July 1 of each year through 2016. The calculation of closure does not include management closures for seeded areas, shellfish relay area closures, local management closures, or temporary rainfall related closures (either local rainfall conditionals or bay-wide closures related to extreme rainfalls). The permanent closure total includes a management area in Little River, Dartmouth which is an under-tested area presumed to have high bacteria. Permanent closures are areas closed year-round. Temporary closures are generally “seasonal closures”, that is, areas closed during the June to September, but in some areas closures may extend from April to November, or longer.

This figure below shows trends by town bay wide. that although shellfish bed closures bay-wide have declined during since 1985. Bay wide total declines through about 2012 were largely due to water quality improvements in New Bedford, Dartmouth, and Fairhaven.  The 2024 closures erase all those gains. When shellfish bed closures in Buzzards Bay are evaluated by town, the picture is less rosy, with shellfish bed closures in some towns like Bourne, Westport, and Gosnold increasing, whereas in other towns the long-term trends are less clear. The 2024 wastewater closures reset the bar for most Buzzards Bay towns.