Sea Nettles Probability of Encounters
See where jellyfish are most likely to appear in the Chesapeake Bay
The jellyfish most commonly seen in the Chesapeake Bay is the sea nettle, Chrysaora chesapeakei. Chrysaora chesapeakei is typically white and most abundant in the tributaries of the middle Bay, where salinity levels range from 10 to 20 parts per thousand (ppt). In the southern Bay, it often features reddish-maroon markings on its long central tentacles and swimming bell. These experimental forecast maps show probability of sea nettle presence, helping reduce the chance of an unpleasant encounter.
Select the desired link to view the Sea Nettle Probability Forecasts (Current Day and Day 2 from latest model run). Select the bottom right link to view the full bay.
Background
Until 2017, sea nettles in the Bay were thought to be the same species found offshore in the Atlantic Ocean. However, a team of scientists discovered that the Bay’s nettles are actually a distinct species, now named Chrysaora chesapeakei, to differentiate them from their oceanic relative, Chrysaora quinquecirrha.
These encounter probability maps are now produced by NOS/NCCOS; they were previously provided by the NOAA/NWS Ocean Prediction Center. It is important to note that while these maps show the likelihood of sea nettle presence, they do not predict jellyfish density, which can vary greatly depending on the year and location. Please also note that these maps are numerical model guidance tools—they are not fully validated and may not reflect real-time conditions.
For more information, the following journal article describes the methodology behind this NOAA product:
Decker, M.B., C.W. Brown, R.R. Hood, J.E. Purcell, T.F. Gross, J.C. Matanoski, R.O. Bannon, and E.M. Setzler-Hamilton. 2007. Predicting the distribution of the scyphomedusa, Chrysaora quinquecirrha, in Chesapeake Bay. Marine Ecology Progress Series 329:99-113.