Report on Local Fish Die-Off

Atlantic Menhaden (Bunker) Die-offs Around Hempstead Harbor and Long Island Sound

Recent fish and wildlife reports for Hempstead Harbor have indicated that things have started this spring a little earlier than usual. On April 7, we had our first report of schools of Atlantic menhaden (bunker) in Hempstead Harbor. Bunker are an important food source for other fish such as striped bass and bluefish, as well as for birds such as ospreys and bald eagles. Over the last several years, the bunker population in Hempstead Harbor and other bays around Long Island Sound has grown, and with the larger population there have been increased incidents of this particular fish being affected by disease and parasites.

Last season, an inexplicable die-off of bunker had been noted all around Long Island Sound. Although bunker are susceptible to die-offs related to low oxygen levels that occur during hot summer months, what had occurred last season extended into the autumn when oxygen levels were much higher. Several state agencies have conducted pathology studies to try to determine the cause of the most recent die-off. Over the weeks in April, there have been reports of bunker kills occurring from Rhode Island to New Jersey. On April 25, there was a report of a fish kill occurring in the Peconic River. A few dead fish were reported seen around Hempstead Harbor and Manhasset Bay.

So far, a Vibrio bacteria (different from the Vibrio bacteria that affects shellfish) has been implicated in the bunker kill, but it is not clear what conditions have caused the bacteria to affect the bunker population. NYS Department of Environmental Conservation (DEC) recommends wearing gloves if you need to handle dead fish and has posted the following, updated notification on its website (

Atlantic Menhaden Fish Kill 2020-2021

DEC and neighboring state agencies have been investigating, monitoring, and tracking an ongoing fish kill event for Atlantic menhaden (Brevoortia tyrannus) since Fall of 2020.

Investigations of affected fish by the New Jersey Department of Environmental Protection (NJDEP) found internal signs of disease associated with the presence of a Vibrio bacterium (link leaves DEC website) in most samples. DEC collected samples of fish found in New York and confirmed the presence of the same Vibrio species in the tissues of the fish. This bacterium is a possible cause of the mortality event. Vibrio bacteria are a naturally occurring bacteria in coastal waters that are typically present in elevated concentrations between May and October. The specific bacterium identified by the DEC and NJDEP is not typically known to be harmful to humans.

There have been no reports of other fish or wildlife species being impacted by the suspected bacterium causing this mortality event. Menhaden occupy estuaries and coastal waters from northern Florida to Nova Scotia and are an important prey species for a wide range of wildlife and are typically used by humans as bait. It is still safe to eat fish that prey on menhaden. As always, it is recommended that all fish and shellfish be cooked to the proper temperature and fish that are dead or appear sick should not be collected or eaten.

In Fall 2020, DEC initially sent samples of tissue from collected fish to Stony Brook University’s Marine Animal Disease Laboratory and Cornell University to test for a viral infection often associated with the observed, irregular, swimming behavior. NJDEP also sent samples of menhaden to Pequest Aquatic Animal Health Laboratory, and samples of menhaden collected by both states tested negative for the virus.

Please also continue to notify CSHH office (516-801-6792, or email of your observations. All of your reports and photos are greatly appreciated and so important to understanding whether local conditions are isolated to Hempstead Harbor or are part of more widespread events.

When reporting observations, please provide as many details as possible. It is most helpful if you include the following information:

  • Date and time of your observation;
  • Location of observation (providing landmarks if possible);
  • Number of fish observed;
  • Species of fish observed;
  • If unable to determine the species, please provide a photo or describe the size, color, and/or shape of the fish, if possible;
  • If fish are alive, provide details on their swimming behavior;
  • If fish are dead, provide details on their condition and external appearance.
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