Dead menhaden cluster at a Navesink River dock in Fair Haven last week. (Photo by Bernie McSherry. Click to enlarge.)
By JOHN T. WARD
A massive fish kill in the Navesink and Shrewsbury rivers in recent weeks is “the most severe mortality event in recent memory,” but New Jersey environmental officials still don’t know why it’s targeting only one species, Clean Ocean Action reported Thursday.
The environmental advocacy group also pressed the state to remove at least some of the dead fish from Red Bank-area waters.
Following up on an April 19 meeting with state Department of Environmental Protection personnel that executive director Cindy Zipf and staff scientist Swarna Muthukrishnan requested last week, COA’s website reported that officials “confirmed fish bacteria Vibrio anguillarum as the cause for this menhaden (aka bunker) die-off.”
“NJDEP has been monitoring these die-offs for years, but this is the most severe mortality event in recent memory,” the Thursday afternoon update said. “This on-going event is also particularly notable because it is caused by a bacterial infection and occurred in colder months (fall/winter), which is atypical.”
The bacterium lives in saltwater, but the fish die-off appears to be limited to menhaden, though “it is unclear why, or if other species could be affected,” COA said. “NJDEP suggested that menhaden may be more susceptible due to their schooling pattern of large numbers, in addition to being abundant.”
Other takeaways from the meeting, according to COA:
- NJDEP is conducting research to determine why the bacterial outbreak is so severe, as there is currently no documented cause. They are also in communication with other state and federal agencies about similar incidents.
- NJDEP is considering developing a monitoring plan. COA recommended and discussed year-round and in-water continuous monitoring in the Navesink and Shrewsbury rivers to assess oxygen, temperature, salinity and other basic conditions. After the meeting, NJDEP confirmed the deployment of a continuous monitoring buoy in the Navesink River off Blossom Cove (east of the Red Bank Rt. 35 Bridge) Â to collect information that may be useful in determining causes for future die-offs.
- While there seems to be no state plan to collect and remove dead fish, COA recommended NJDEP consider deploying skimmer boats to collect fish during high tides to reduce the wash-ups.  These boats have been used in the harbor area to scoop up garbage slicks before they spread out to sea or onto beaches. They have shallow drafts and are used in many harbors.
- As NJDEP continues to track the menhaden, they appreciate additional reports from citizens. In addition to reports on dead menhaden, they also welcome citizen observations on other species that are found dead or exhibiting sick/spinning behaviors. To share your observations with COA, please submit reports through the Two Rivers Water Quality Reporting Form. Reports submitted through this form will be shared with NJDEP.
- NJDEP recommends citizens avoid contact with the fish. NJDEP officials described that while this is a fish-specific bacteria, it is opportunistic, and if someone has a suppressed immune system or has an open cut or wound exposure, they could be at risk.
- NJDEP plans to post answers to Frequently Asked Questions on the agency website to inform the public soon. Their recent statement from April 16, 2021 can be viewed here.
COA said that while it applauds the DEP for providing a “swift and detailed briefing,” it again called on the agency and the state Department of Health to host a virtual public forum to update citizens and provide a means for questions and answers.
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