How does this information relate to fish advisories issued by the Massachusetts Department of Public Health (DPH)?

The Massachusetts Department of Public Health (DPH) evaluates all fish contaminant test results from MassDEP to determine whether a fish consumption advisory is needed for fish from specific locations. DPH and MassDEP have collaborated on fish sampling and analysis for 30 years, and as a result, many more lakes have been surveyed for contaminants in fish than the ones in the MassDEP research program. The complementary Public Request Sampling Program samples a larger universe of lakes, ponds, streams and rivers for more contaminants than mercury. The program samples fewer numbers of fish per lake, and combines the individual fish for analysis as composites. More species are sampled than in the MassDEP research program. That dataset is not available electronically. The primary purpose of the program is to provide data for health advisory screening. A searchable database of all fish advisories is available through DPH (including advisories for lakes sampled outside the scope of the research database).

The MassDEP research program data portal gives access to data from 39 lakes that are retested for fish mercury on a rotating basis. The research program is a statistically-based sampling program conducted to answer specific questions concerning mercury in Massachusetts aquatic ecosystems (e.g., do fish in one area of the state have more mercury than in another area? Do fish mercury concentrations change over time?).

Why not put all of the fish data collected by the state in the data portal?

The fish surveys conducted by DPH in collaboration with MassDEP consist of many species of fish. Fish of the same species collected from the same location are analyzed as composites. They are analyzed for many contaminants. Those data have more limited utility than the data collected for the research database. Fish collected as part of the MassDEP research program are analyzed only for mercury. They are analyzed as individuals, and the sample sizes are generally larger, to facilitate statistical analysis. The two groups of data have other differences, for example, the accuracy of testing methods, and the methods themselves, have changed over the past 30 years. Because of the differences in the data sets, they have not been merged into a single data set.

What lakes are sampled as part of this research?

The lakes are listed in the Text Search application. As more data are added to the database, additional lakes will be listed. A complete list of the 39 lakes along with sampling schedules can be found here:  Fish Mercury Sampling Schedule for 39 Massachusetts Lakes pdf format of Fish Mercury Sampling Schedule for Massachusetts Lakes

How often are the lakes sampled?

Approximately 12-18 lakes are sampled every other year on a rotating basis. A complete list of the 39 lakes along with sampling schedules can be found here: Fish Mercury Sampling Schedule for 39 Massachusetts Lakes pdf format of Fish Mercury Sampling Schedule for Massachusetts Lakes

Where can I find more information on the MassDEP fish research?

Results of the ongoing research are available by following the Environmental Monitoring link on the MassDEP Mercury page.