Photo: Courtesy of MassWildlife
WESTBOROUGH, Mass. (WBZ NewsRadio) — Dead fish are piling up on the shores of water bodies across Massachusetts, leaving residents to wonder what might be wrong with their local lakes and ponds.
The phenomenon is called a "fish kill." It can happen any time of year and can occur naturally.
In the winter, fish kills often occur when snow and ice blocks light from entering the water column. Without light, the oxygen level in the water decreases because plants cannot perform photosynthesis to replenish oxygen that is being consumed by decomposing plant matter on the floor of the water body.
"So we have less light, less photosynthesis, and then less dissolved oxygen," said Jason Stolarski, Watershed Project Leader with the Massachusetts Division of Fisheries and Wildlife. "All the while, that decomposition is occurring at the bottom."
Fish kills that happen naturally are not usually cause for concern, although this winter's snow has resulted in the most active fish kill season in "about 10 years," Stolarski said.
"Those fish that are floating in those ponds are being consumed by turtles [and] birds of prey," Stolarski said. "So while it is detrimental in the short term to the fish population in that particular water body, they are beneficial to other consumers in the terrestrial environment."
What concerns researchers is fish kills that occur for unnatural reasons, like pollution.
MassWildlife urges residents to report piles of dead fish to the Massachusetts Environmental Police so researchers can make sure there are not unnatural pollutants in the water.
"In my tenure here at MassWildlife, there have only been a handful of kills that resulted from pollution," Stolarski said. "But those are the ones we really need to respond to quickly because, if there is something in the water, we need to have the right personnel on site to contain it [and] to make sure it does not get any worse."
The Massachusetts Environmental Police can be reached at 800-632-8075.
WBZ NewsRadio's Jay Willett (@JayWillettWBZ) reports.