Shellfish Harvest Opportunities
How much of our estuaries are open for shellfish harvesting and how has it changed over time?
The percentage of possible acre-days (i.e. the number of open acres multiplied by the number of days those acres were open for harvest) between 2012 and 2016 was 80% and 66% for the Great Bay and Hampton-Seabrook estuaries, respectively. This continues the long-term trend of a gradual increase in acre-days. The next reporting period may see continued increases as the Portsmouth wastewater treatment facility upgrade is completed in 2019.
The areas designated as “conditionally approved” (open but subject to temporary closures due to water quality issues), “restricted” (closed due to chronic water quality problems) and “prohibited” (closed due to water quality issues that require further investigation) have remained fairly constant since 2004 (Figure 11.3). The most notable change occurred in 2014 with the conversion of over 1,300 acres that was “prohibited/unclassified” area (closed because the water quality is unknown) to “prohibited/safety zone.” This refers to areas closed due to pollution sources that may unpredictably affect the water quality of the area and create a potentially dangerous public health risk. These zones are most often related to WWTFs.
This 2014 conversion was a direct result of the December 2012 Portsmouth wastewater treatment facility (WWTF) dye study46, which examined how this primary WWTF affected water quality in the estuary, and how those effects might change once the facility upgrade is complete in 2019. The dye study indicated effluent travels further up river and faster than previously determined; this resulted in the reduction of harvest opportunities at the Little Bay and Bellamy River shellfish beds (Figure 11.1). Specifically, harvest days were reduced from seven days/week to Saturdays only, from 9 a.m. to 5 p.m.; this approach gives wastewater operators and the NHDES Shellfish Program more time to react in the event of a WWTF problem that occurs overnight. (Note: aquaculture operators in Little Bay are mandated to call the NHDES Shellfish Program before harvesting and so are not impacted by the new rule).
Maine waters, including areas of the Piscataqua River and Spruce Creek are also closed due to concerns about the Portsmouth WWTF. This facility is being upgraded from primary to secondary treatment, which should greatly reduce both the risk of bacteria/viral contamination during failure events as well as improve overall water quality. When the Portsmouth upgrade is complete, NHDES and Maine Department of Marine Resources will reassess the public health risks and modify harvesting classifications accordingly.