MERIDEN — Officials believe hundreds of dead fish at Broad Brook Reservoir died naturally as a result of stress from reproducing.
Public Utilities Director Dennis Waz said he believes the Sunfish died from spawning, which occurs seasonally as water temperatures rise.
Fish kills related to spawning are not uncommon during the spring and early summer months, and bass and sunfish are more susceptible, according to a fact sheet from the state Department of Energy and Environmental Protection’s Inland Fisheries Division.
“All the fish were the same species, Sunfish, which are prone to natural kills during spawning,” Waz wrote in an email this week.
Waz said the city investigated and has notified DEEP.
Broad Brook Reservoir, located along River Road near the Cheshire-Meriden town line, supplies drinking water to Meriden residents. The water goes through a full treatment and chlorination process.
DEEP is currently looking into the fish kill and “will have more to share later,” spokesman Lee Sawyer wrote in an email Wednesday.
According to DEEP, fish die as a result of spawning because the process requires a lot of energy, weakening them and making them more susceptible to bacteria and other environmental factors.
“Fish can get scrapes and lose scales from the rocky bottoms during nest building which can create an open wound, giving bacteria a point of entry,” the DEEP fact sheet states. “Secondary infections, such as bacteria can easily move in, overtake and eventually kill the fish. Spawning related fishkills gradually occur over a two to four week period with dead fish tending to accumulate along wind-prone shorelines.”
Fish that die as a result of spawning commonly develop a bacterial infection caused by “Aeromonas spp.”
“Aeromonads are among the most abundant bacteria found in freshwater aquatic habitats. They are so abundant that they can be isolated from the skin and intestinal tracts of healthy non-stressed fish,” according to DEEP.
DEEP says spawning-related fishkills are “natural occurrences and are rarely serious in the long run because lakes and streams support thousands of fish per acre.”
“Fortunately, fish have generally already spawned so the new generation will repopulate the lake, pond or stream,” according to DEEP. “Fish kills can sometimes be beneficial for the fish community by reducing weak, older or slow-growing fish.”