By Elizabeth Wulfhorst
As reported last week in The Two River Times, local waterways and river banks have been awash in dead fish recently, an occurrence that seems to be increasing.
Swarna Muthukrishnan, Ph.D. the staff scientist for Clean Ocean Action, explained the scenarios during which this phenomenon might occur, which included natural (varying oxygen levels in the water), man-made (climate change, toxic runoff) and bacterial.
And the New Jersey Department of Environmental Protection (NJDEP), has now determined that a Vibrio bacterium specific to fish seems to be causing the current fish kills in the area, according to information from COA.
Residents and others along the Navesink and Shrewsbury rivers may be used to seeing the dead menhaden – an oily fish harvested by fishermen for chum and for use in sup- plements, livestock feed and cosmetics, among oth- er things – at certain times throughout the year. A filter fish at the bottom of the food chain, menhaden, or bunker fish, swim in schools and are the favorite prey of larger fish and marine birds. They are often chased into shallow waters and, during warmer months, die from the low levels of dissolved oxygen in those areas.
But dead fish began showing up in November and December, two colder months that don’t usually fit this pattern, and the fish were seen “spinning” in the water before dying. Sightings increased dramatically this past week.
Rick Swanson, a 20-year resident of Fair Haven, said he has seen the dead fish wash up every year and agreed that this year is especially bad. He lives where Fair Haven meets Red Bank at what he called an “elbow” in the Navesink River. “The wind and the current go right into the corners and we get everything that washes up,” he said. This week that included thousands of dead menhaden.
“They’re coming in almost like an oil slick,” Swanson said. “This is definitely several times the volume of anything we’ve ever seen.”
According to COA, the NJDEP confirmed that a neurological bacterium specific to fish, most closely related to Vibrio anguillarum, is the culprit. COA called for “fast federal and state funding to research this Vibrio species, the effects to menhaden, other fish, and the food chain as well as other impacts and possible solutions.” It is requesting a task force comprised of the waterways’ stakeholders to find solutions to the problem.
Swanson said he was not surprised to learn about the bacterial infection. “There’s been something wrong with the river for a while,” he said. “The level of brown out there that you see, it’s not just algae that comes in August when it’s super hot. It’s like a muddied water that you think, ‘Wow, this is not right.’ ”
Similar fish kills were reported in New York, Connecticut and Rhode Island this fall. The NJDEP’s investigation found high levels of a species of Vibrio in all the fish it sampled which suggests the bacterial infection is a major factor in the recent fish kills. According to COA results are still pending from recent samples the NJDEP collected from the Navesink River.
Vibrio anguillarum is commonly found in ocean and brackish waters during warmer months and causes Vibriosis.
Right now Swanson’s concern is focused on cleanup. He’s hoping someone from the borough will address what to do with the thousands of dead fish currently rotting on the shores and the thousands more floating in the water that will eventually wash up near docks and homes – especially if a bacterium is confirmed from current samples to be the cause.
COA is looking for citizen-scientist observers to document this and future menhaden mortality events. Contact the NJDEP through the WARN DEP Hotline at 877-WARN-DEP (877-927-6337). For more information on how to report fish kills, including a fish kill reporting form, visit NJDEP Division of Fish & Wildlife at nj.gov/dep/fgw/fishhealth_fishkills.htm.
This article originally appeared in the April 8 – 14, 2021, print edition of The Two River Times.
