Sunfish carcasses litter the shoreline of Bare Hill Pond.
(Photo by Lisa Aciuekewicz)
The sudden appearance of dead fish floating at the edge of Bare Hill Pond Tuesday sent several town officials looking for answers. The approach of Memorial Day weekend, only three days away, added urgency to assessing the health of the pond. But by Wednesday, with test results not yet back, evidence suggested the unexpected fish kill would turn out to be a natural phenomenon and not a cause for alarm.
Tuesday morning, DPW worker Robert Szocik noticed about 30 dead fish floating at the water’s edge around the town beach and out in the water. He alerted Conservation Agent Liz Allard, who investigated the situation with town sanitarian Ira Grossman. Grossman took a water sample to send to the state lab and later contacted the Massachusetts Fisheries and Wildlife Division.
The Bare Hill Pond Management Committee and the Parks and Recreation Commission were alerted, while sightings came in from other areas of the pond. A Willow Road resident counted 130 dead fish at the north end of the pond near the dam Tuesday afternoon.
Unfounded speculation widespread
Speculation was widespread among general residents, from algae blooms to toxic contamination—herbicide, pesticides, or unlawful dumping into the pond perhaps. A fisherman wondered if too much catch and release during a bass run over the weekend was the problem.
The Pond Committee’s wetlands consultant, biologist Wendy Gendron, has been performing wetlands biology monitoring for the committee for about eight years. She gave the pond her professional eye and did not detect an algal bloom. She also confirmed that the fish were mostly the same species, a critical factor in assigning a natural versus toxic interpretation. Fish kills in which only one or two species are involved are almost always natural events.
Pond Committee Chairman Bruce Leicher identified the dead fish as sunnies—bluegills or pumpkinseeds.
Gendron suggested oxygen depletion as the most likely explanation.
A combination of factors at this time of year can deplete oxygen in a pond. According to the Fisheries and Wildlife, fish kills are common in the spring when spawning brings large numbers of fish together in shallow areas. Over-competition for oxygen can stress them, particularly when dissolved oxygen concentrations can fluctuate widely in response to weather and algae.
Test results were still not back Wednesday afternoon, when the Press went to the printer, but Leicher was hopeful. “Fishermen report excellent fishing. Our water quality ratings in April were excellent, and phosphate levels were half of what they were 10 years ago.”
