Water Tampers with Fish Hormones, Causing Males to Develop Female Traits

By Michael Hill

Raymond Gallagher jogs through the Wallkill River National Wildlife Refuge but he had no idea he was crossing paths with gender-crossing fish.

“This is really concerning for me because, you know, I like this area. I live around this neighborhood,” he said.

Over the last several years, the U.S. Geological Survey has tested the water and nearly 300 fish in 19 wildlife refuges in the northeast, including the Wallkill River and Morris County’s Great Swamp. It found that something in the water is tampering with the hormones of 85 percent of the male smallmouth bass and a quarter of the male largemouth bass and causing them to develop female reproductive traits.

Fred Pinkney co-authored the study.

“It resonates with the public when you see things like this that scientists frankly don’t fully understand,” he said.

One male largemouth bass from the Great Swamp but all five male smallmouth bass from the Wallkill showed the female traits. It’s a phenomenon researchers say they’re finding across the country and the world, leading to some to wonder if this is naturally occurring.

“Really this is just pointing attention to the widespread nature of this problem,” Pinkney said.

As a society, America has gotten smarter about disposing of medications, that is, after years of flushing birth control pills and other prescription meds down the toilet only to have them show up in waterways. In the Wallkill, researchers suspect it’s one of several culprits or a combination of pharmaceuticals from human waste that the upstream water treatment plant can’t filter or antibiotics fed to livestock or pesticides from farm runoff. Pinkney says the Wallkill points to human influence because all five fish are “intersex.” It qualifies the popular New Jersey to New York fishing spot for a follow up study. In the meantime, researchers and river keepers wonder about the impact of eating any of the “contaminated” fish.

“In the meantime it amounts to an uncontrolled experiment on environmental and human health,” said Water Quality Program Manager Dan Shapley.

What’s disturbing to river keepers and researchers is the refuges are protected lands meant to keep pollution away from fish, water and wildlife.

“If we’re seeing effects of pollution there we would suspect that we’re seeing it in waters that are less protected as well and that is certainly concerning,” Shapley said.

“It shows we need to do a better job to protect all our watersheds,” Pinkney said.

Whenever researchers get the money to go beyond the initial study and do a definitive one, it won’t be soon enough for river keepers, other environmentalists and even the government. For many want to know why many of the fish here are developing female reproductive traits whether it’s a quirk of nature, or whether it’s something humans have done intentionally or inadvertently to the water.

We’re in this together
For a better-informed future. Support our nonprofit newsroom.
Donate to NJ Spotlight