By Elizabeth Wulfhorst
Clean Ocean Action (COA) executive director Cindy Zipf made sure everyone knew from the outset that the May 27 Rally for the Two Rivers meeting was going to be all about the fish. Local and state authorities, in addition to residents and environmental organizations like COA, have been concerned about the recent massive die-off of menhaden – or bunker – in the Shrewsbury and Navesink rivers.
Representatives from the New Jersey Department of Environmental Protection (DEP) and local government leaders spoke about their findings and answered questions about the now over two-month-long mortality event.
While he could not promise they would “have all the answers,” Ray Bukowski, DEP assistant commissioner of natural and historic resources, said the state has been working hard to find the cause of the die-off.
“This is an important topic,” Bukowski said. “I just want to stress that from the outset, that DEP has been focused on this for quite a long period of time. We understand the impacts to quality of life in and around the rivers. We also share in all the concern that everyone has for natural resources, making sure that our fish populations are healthy, under- standing what potential health effects it could have on human beings.”
As assistant commissioner, Bukowski leads the Division of Parks and Forestry, New Jersey Forest Fire Service, Green Acres Program, Division of Fish and Wildlife, and the Historic Preservation Office.
Menhaden die-offs and kills have been documented for decades and have been the focus of studies since the 1980s from Rhode Island to Virginia, Bukowski explained.
“It is not just an issue on these two rivers,” he said, “but it is an issue that we are trying to understand the best that we can so we can take any steps we possibly can to minimize these impacts to the fish populations and to minimize the effects on everyone’s quality of life.”
This current event is a die-off, he explained. A kill occurs when oxygen levels in the water are depleted to the point where massive amounts of fish die “in one fell swoop.” Menhaden, an oily fish harvested for bait and for use in the cosmetics and livestock industries, swim in dense schools. They are often chased by predators into smaller bodies of water where they use all the oxygen and die. They can also die when outside factors like stormwater runoff affect the nutrient levels of a waterway and cause a decrease in dissolved oxygen.
A die-off, by contrast, occurs when large quantities of fish die from a different cause over a longer period of time, called “chronic duration mortalities,” according to Jan Lovy, Ph.D., the NJ Division of Fish & Wildlife’s fish pathologist. He said samples from this event, which began around March 25, show the cause of this die-off is a Vibrio bacterium normally present in marine environments and in the menhaden’s gut.
As previously reported, “periodic samplings in March, April and May confirmed the bacterial disease vibriosis caused by the bacterium Vibrio anguillarum.”
Lovy stressed that this particular Vibrio bacterium is “not one that has an effect on humans,” calling it “mostly a fin fish pathogen” that currently seems to be affecting menhaden only.
Bob Schuster, chief of the NJ DEP’s Bureau of Marine Water Monitoring said 70 species of Vibrio exist in the environment and only a handful impact humans. “This is not one of them.”
Schuster said the ones that do affect humans are monitored under the DEP’s safe shellfish program. Periodically there are Vibrio bacteria illnesses reported in humans around the country but most of those are associated with improper handling of shellfish, he said.
And Schuster confirmed that this die-off, while disturbing on many levels, was not causing concerns “from a human health perspective.”
He said the bureau worked with the Monmouth County Health Department to get additional samples to see if the die-off was impacting bacteria levels in the water. They are still monitoring and it is “an ongoing process,” Schuster said, but they are currently not seeing an issue with water quality. “I would not be concerned with paddleboarding (or) other activities” on the water, he said.
As far as eating other fish caught in the rivers that might be preying on the menhaden, Schuster noted, “As this bacterium does not affect, you know, humans, it is not a concern from the consumption of fish side.” He stressed that fish should always be cooked before consuming because that kills any bacteria present.
The NJ DEP posts fish consumption advisories online with guidance on how to clean and cook fish and maps showing any issues with specific bodies of water.
“We have not had documented cases of other predatory fish, gamefish, like striped bass and bluefish, things like that, that have succumbed to this bacteria,” said Bukowski.
And there hasn’t been any documentation of an impact to birds or mammals or even crustaceans, he added. When questioned why birds were not eating more of the menhaden, Bukowski said he thinks it was simply because the die-off was so large. “There was quite a bit of food available and they can only eat so much.”
Towns across the Two River area could attest to the amount of fish available. Oceanport Mayor Jay Coffey spoke about his town’s cleanup efforts which involved the hiring of an outside contractor that spent four days clearing the borough’s shores and water ways of dead fish.
State Sen. Vin Gopal (D-11) called the mounds of dead and rotting fish, “One of the most disgusting things I’ve ever seen.” He has been working closely with shore towns to secure funding for cleanup through the state and federal government.
“We have a small window because of the federal resources that came in this year from the recovery act (American Rescue Plan Act) where we might be able to get some help with this,” Gopal said.
He said the die-off posed “big challenges with quality of life” for local towns and worried the events like this in the future could decimate small municipalities’ budgets.
As Coffey pointed out, the towns were at the mercy of “winds and tides” when it came to where the dead fish ended up. Gopal is currently submitting reimbursements for Oceanport, Long Branch and Monmouth Beach but has also reached out to all the other municipalities impacted to see if they need or want state help.
Bukowski praised Coffey and Gopal for “taking the bull by the horns” (or, as Zipf suggested “taking the fish by the gills”) and getting the job done for the residents of these hard-hit areas.
If residents are still plagued by dead fish on their property, Bukowski recommends raking them back into the water and letting the environment take its course; double bagging smaller quantities and putting it into the garbage; or if you only have a few, burying them in your garden as fertilizer – the bacteria will not hurt the soil.
As the die-off begins to die down – Lovy said it was harder to find samples in May, hopefully an indication that this is the “tail end of this mortality” – the question now becomes what caused this bacterium to multiply within the fish population to the point where it became deadly on such a large scale. Knowing this could help prevent future die-offs or quicken reactions when one occurs.
Bukowski said it is going to be difficult to pinpoint one exact cause. He said it is likely they will not find “a single smoking gun” but that it rather will be a combination of factors.
He said all fish can be immunocompromised coming out of the cold winter months, so mortalities do occur more frequently in the spring. Temperature, oxygen levels, salinity, tidal flows and the density of the menhaden schools – these fish are “horrible at social distancing,” joked Bukowski – all could play a part.
COA representatives asked if sewage and other pollutants in the rivers, something the organization fights hard to prevent, could have caused the bacterial growth. None of the state representatives thought that was the case, which pleased Alison Jones, COA Watershed Program coordinator.
She said it was “good to hear” that sewage was not playing a part.
“It may not be pollutants from the stormwater, it may be something as simple as salinity changes” from the amount of stormwater, Schuster said.
There was no hard freeze this winter either, which could be a factor.
“As we keep studying this, working together within our department and other partners, we’re going to learn a lot more,” Schuster said.
Something in the menhaden physiology is making them “more reactive” to this bacteria, said Bukowski, while also noting that “the menhaden population overall is very healthy. Overall the stock is very high, very healthy across the entire region,” which is heartening. Researchers will be looking for trends.
One final item Lovy noted was that May samplings were showing a “second bacterial species” called Yersinia ruckeri, also a fin fish pathogen. He said it could be “acting as an opportunistic pathogen” on an already stressed fish and noted that it also posed no risk to humans.
“The DEP is still trying to understand all of the environmental factors that were involved in this particular fish die-off but even before this mortality event we knew that the Navesink and the Shrewsbury rivers were facing water quality issues,” Jones said.
She said events like this help us become more “aware of our impact on our local water quality, which goes in hand-in-hand with understanding the things that we can all do personally to help improve our water quality.”
The next Rally for the Two Rivers meeting is scheduled for 7 p.m. Thursday, July 29. But before then, local citizen-environmentalists can join COA at the third annual Eco-Fest from 9 a.m. to 12:30 p.m. June 5 at Victory Park in Rumson. The event, co-hosted by the Rumson Environmental Commission, features family-friendly education programs and experiences.
Rally for the Two Rivers is “a focused alliance of around 30 organizations and all municipalities working to improve water quality in the Shrewsbury and Navesink rivers,” coordinated by COA, explained Zipf.
Wrapping up the virtual meeting, Zipf thanked and “blessed” the contractors who cleaned up the rotting fish, adding that she would not have been able to complete that task.
This was “a nasty little stinky fish on top of what was really not a really fun year,” Zipf said.
This article originally appeared in the June 3 – 9, 2021, print edition of The Two River Times.
