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Status and Trends: LISS Environmental Indicators

Approved Shellfish Acreage

CT Dept of Agriculture/Bureau of Aquaculture


Approved Conditionally Approved Restricted Prohibited
2005 149,265   79,283 138,048 23,328
2006 134,870   93,048 138,678 23,328
2007 134,039   93,764 138,784 23,337
2008 134,039   93,764 138,735 22,708
2009 133,580   93,836 138,873 22,954
2010 134,524   92,818 138,833 23,071
2011 128,175   99,156 138,573 23,342
2012 127,884   99,132 138,849 23,384
2013 126,416 101,131 138,480 23,220
2014 126,416   95,567 141,503 25,761
2015  126,416   95,598 141,611 25,622
Approved growing area where direct marketing is allowed and water meets certain bacterial standards. Conditionally approved growing area meets the criteria for an Approved classification except under certain conditions, for example, under dry weather up to 1.0” of rain, or seasonally when boats are removed from an area.  Restricted growing area is subject to a limited degree of bacterial pollution but may be relayed to other cleaner areas of the Sound for cleansing. Prohibited growing area is subject to contamination by a sewage treatment plant or otherwise contaminated by deleterious substances and may only be used as a source of seed oysters.
New York
Certified Seasonal* Uncertified
2000 410,552    942 77,518
2001 410,552    942 77,518
2002 410,597    879 77,473
2003 410,597    879 77,473
2004 410,336    961 77,734
2005 410,336    961 77,734
2006 409,934 1,650 78,136
2007 409,934 1,650 78,136
2008 409,889 1,650 78,181
2009 409,889 1,650 78,181
2010 409,889 1,650 78,171
2011 412,093 1,690 75,424
2012 412,018 1,613 75,499
2013 411,623 1,994 75,513
2014 411,623 1,994 75,513
2015 411,252 2,293 75,585
2016 411,252 2,293 75,585
Certified shellfish areas are of such condition that shellfish may be taken from there for use as food. Uncertified shellfish lands are areas from which the harvesting of shellfish for use as food is prohibited. Seasonally certified areas are uncertified (closed) during several months of the year, usually from late spring through late fall due to documented water quality problems during the warmer months of the year. Other seasonal closures are around marinas and boat mooring areas because of the potential for sewage discharges from marine toilets. *Seasonally certified (closed) acreage is a subset of total uncertified acreage, and its acreage is also included in the uncertified shellfish lands column.


In New York, shellfish lands are defined as all tidal or saline waters within the marine district and the lands lying thereunder, including such lands which are exposed at low tide. In Connecticut, shellfish growing areas are defined as any area that supports or could support the growth and/or propagation of molluscan shell stock (live clams, oysters, mussels and scallops in their shell). Both states reevaluate shellfish areas for improvements or degradation of water quality and status of pollution sources, and to determine whether it’s classification for harvesting species should be upgraded or downgraded..


Approved shellfish acreage indicates whether water quality in embayments and tidal rivers and in open waters near the shore are able to support the harvesting of shellfish for human consumption.


In Connecticut, the vast majority of classification changes  in 2014 were administrative in nature, rather than resulting from water quality issues impacting shellfish growing areas.  For example, there were a number of classification downgrades from Restricted to Prohibited in portions of rivers that are not active shellfish areas and are not able to be sampled at the frequency necessary for the areas to remain active growing areas.  Also, a large reclassification of 5,531.81 acres from Conditionally Approved: Administratively Closed  to Restricted occurred in Old Saybrook at the mouth of the Connecticut River.  The location had been under administrative closures for many years, and only briefly supported a shellfish program many years ago. The acreage extends all the way to the New York-Connecticut mid-Sound boundary.  In New York, the 2015 changes in classification were water quality related and there were two emergency closures related to excessive rainfalls in August and September.

Shellfish areas can be temporarily closed as a result of naturally occurring pathogen outbreaks and harmful algal blooms. Closures due to shellfish-related food borne illnesses caused by the naturally occurring (not sewage or pollution related) marine bacterium Vibrio parahaemolyticus resulted in the extended closure of Connecticut’s most productive oyster grounds in Norwalk and Westport in both 2012 and 2013. New York’s most productive shellfishing area, Oyster Bay Harbor, was closed for several weeks in 2012.   In New York, Oyster Bay Harbor and Cold Spring Harbor were closed for several weeks in 2013 after several confirmed Vibrio parahaemolyticus illnesses were traced to those harvest areas. Wide-spread illness due to a virulent strain of this bacteria plagued the East Coast during the summer of 2013, with other  states including Massachusetts, New Jersey and Virginia also closing shellfishing areas after experiencing illness outbreaks caused by Vibrio parahaemolyticus.

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Flowers Oyster Barge in Oyster Bay. Photo taken by Matthew Graff during NYSDEC Shellfish Sanitation sampling event.

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