Computer Applications for Shellfish Bay Sanitation Analysis, adjusting SHELLFISH Harvest Closure Rules AND BAY MANAGEMENT

Pearl and Aquarius are shellfish sanitation models that are now combined into a single application. The applications is a powerful tool capable of rapidly analyzing Public Health shellfish sanitation datasets to monitor bay conditions over multiple years, characterize fecal coliform concentrations by time and magnitude, micro-adjust shellfish harvest closure rules and assist in overall bay sanitary management. The models employ the identical equations and procedures as mandated by the National Shellfish Sanitation Program (NSSP), Model Ordinance, but in place of regression analyses the models employ non-regression equations that consider sample size, and increase sensitivity of analyses.   

Although the total model applications are named Aquarius, the heart of the system is now Pearl. The Pearl model can be used in one of two modes; in the stand-alone mode Pearl performs multi-year analyses, for example 30 years, using observed fecal coliform data collected from within shellfish growing areas to profile fecal coliform concentrations to profile the historical conditions, and determine that under current closure rules if harvesting shellfish from those areas may pose a human health risk for shellfish consumers. Pearl outputs are scattergrams that illustrate data points appearing as either in the True Positive, False Negative, or True Negative zones relative to the NSSP 14/43 MPN/100 mL standard and the Pearl 8/26 MPN/100 mL standard for a 5-tube test (Fig. 1). The model also adjusts the zones to match conditions for a 3-Tube Test, 12-Tube Test, Membrane Filter (MF); and Restricted 3-, 5-, and 12- Tube Test.

Shellfish growing areas that are identified "at risk" through the stand-alone Pearl analysis under current rules are candidates for closure rule adjustments. Pearl is then operated in tandem mode with Aquarius, and the two models can be used together to micro-adjust closure rules and maximize the number of days a shellfish growing area can remain open to harvest with no increased risk of illness to shellfish consumers.