Clinging Jellyfish Out In Force In Metedeconk River In Brick

BRICK, NJ — The warming water and warm temperatures may have you considering taking a dip in the bay or the river, but authorities are urging people to exercise caution as clinging jellyfish have been found in northern Barnegat Bay.

Clinging jellyfish, the non-native species whose presence was first confirmed in New Jersey in 2016, deliver a powerful sting, and the state's rivers and bays have been monitored for them ever since by the state Department of Environmental Protection and by scientists at Montclair State University.

In 2024, the clinging jellyfish have been found in North Wildwood and northern Barnegat Bay with the heaviest concentrations in the Metedeconk River, according to Paul Bologna, a biology professor and the director of the Marine Biology and Coastal Sciences Program at Montclair State University.

Bologna has been researching and monitoring the jellyfish for several years and posts updates on the New Jersey Jellyspotters group on Facebook.

"The season is starting with a bang. We collected around 300 clinging jellyfish in northern Barnegat Bay," Bologna wrote May 31 in the Facebook group. He said multiple sites sampled in the Metedeconk River produced many large clinging jellyfish "so be careful where you wade."

The water at Tices Shoal, the popular boaters' hangout behind Island Beach State Park, has not yet been sampled but Bologna said people should be careful. "Keep your eyes open and if you see any please let us know!"

A map maintained by the state DEP shows where clinging jellyfish have been confirmed and sites that have been investigated but no clinging jellyfish were found (click here).

The clinging jellyfish, a native of the Pacific Ocean, is small and very difficult to spot in the water. They range from the size of a dime to about the size of a quarter and have a distinctive red, orange or violet cross across their middle.

Both the adult, or medusa, and polyp stages of the clinging jellyfish are capable of stinging, a mechanism the species uses to stun prey and to defend against predators. Each jellyfish can trail 60 to 90 tentacles that uncoil like sharp threads and emit painful neurotoxins. Tentacles grow to be about 3 inches long, and they primarily feed on zooplankton.

They are not known to inhabit ocean beaches or other sandy areas but tend to attach to submerged aquatic vegetation and algae in back bays and estuaries. Anyone wading through these areas, especially near aquatic vegetation, should take precautions, such as wearing boots or waders to protect themselves. Swimming at lifeguarded beaches is always encouraged.

A sting can produce severe pain and other localized symptoms and can result in hospitalization in some individuals. There is no method to effectively control clinging jellyfish populations in the aquatic environment.