Yesterday, the men cutting our grass called my attention to several dead fish in the shallow water near our shore. They pulled two out for me. I could see three others lying nearby on the bottom. They were small fish, Bluegills, a type of sunfish. This may be nothing more than a case of suffocation from oxygen depletion in the stagnant, shallow areas of the pond. After all, there’s been little rain, and the pond has not has not seen much water replacement.

It’s also a reminder that Chester Brook, the discharge channel for Hardy Pond, is still silted up two years after the great floods of March 2010. Proper flushing of the pond depends on a free-flowing outlet. This quarter-mile stretch badly needs to be cleaned out, as an outside engineering study recommended in late 2010. As of this writing, more than a year after the report, little or nothing has been done.

Update, July 2012:  Opinions have varied as to the size of the fish kill. At the time, someone at Windsor Village, a rental community on the eastern shore of the pond, reported it to MassWildlife as a “small” fish kill. As stated above, I saw only a few dead fish in the water here on the western shore. Others have put the numbers much higher. Recently, Marc Rudnick, writing for the Hardy Pond Association reported that, “Thousands of sunfish are dead in the pond…”

Perhaps the best clue, one that supports Marc’s description, is the complete disappearance of cormorants and gulls from the pond this summer, two species that depend on the small fish. The gulls perennially have been a large and noisy presence. In recent years, the Double-crested Cormorants have ranged in number from several individuals to an occasional flock of six.

More information on fish kills, and their seasonal nature, can be found at MassWildlife.

See related posts: High Water*, High Water II*, High Water III, and Mono Lake*. See also the permanent page: The Great Flood. Click image to enlarge it, and browser’s back arrow to close. Comments are welcome.


5 Responses to Dead Fish*

  1. Marc Rudnick says:

    Many people have contacted the Waltham land Trust and the Hardy Pond Association about the fish kill at Hardy Pond. Here is what we know to date:

    Thousands of sunfish are dead in the pond – they seem to be the only species affected. We’ve seen lots of swimming and massing bass in large numbers.

    There are many reasons for fish kills, most are natural events resulting in a reduction of dissolved oxygen.

    There have been one or two larger fish kills in Hardy Pond in the past 10 years.

    Treatment of aquatic plants is not likely to be a direct cause – the chemicals are short-lived in the water and the treatment occurred about 9 months ago.

    With or without treatment, the mass of rotting vegetation in the pond contributes to oxygen depletion as do cultural inputs of nutrients. The continued dumping of materials into the storm drains, the street construction projects on Hardy Pond Road, and many other factors add to nutrients being washed into the pond.

    Some experts contend that the early disappearance of pond ice and unseasonable warm weather can be problematic. As the water warms and the water column turns over, the deoxygenated layer mixes quickly into the level where the fish are swimming. Fish become stressed by low oxygen and also become suseptible to viral and bacterial infection. When this occurs very early in the season, there is little offsetting oxygen being delivered by living green aquatic plants.

    Toxic input is certainly a cause of fish kills, and is it impossible to know when toxics get introduced through the storm drains or directly by dumping — we are unaware of any such events recently. The thriving pond life (other than sunfish) make this a less likely scenario.

    Low oxygen and high nutrients can also encourage explosive growth of harmful algae.

    All evidence so far points to a natural die-off of the fish, in a pond that suffers habitually from low dissolved oxygen, with unusual weather contributing. This does not eliminate the possibility of toxic or damaging inputs by human, and we will continue to seek more information and better answers.

    Marc Rudnick for the
    Hardy Pond Association

  2. I have seen them near the rocks on the other side as well.

    It’s weird that just this one species is affected.

    There are catfish and largemouth in there and I haven’t seen any dead ones just these guys.

    • Ron Cohen says:

      Interesting. Could the bluegill be smaller and so enter shallower waters where there is less oxygen? Or, could it simply be more sensitive to whatever is causing the die-off?

      • Jim Fett says:

        Indeed, bass and especially catfish are hardier souls. Also, since there are no doubt many more blugills/panfish in the pond than any other types, their dead might be more noticeable whether natural or unnatural die-offs – just due to sheer numbers.

  3. Jim Fett says:

    I am also worried about the clogged outlet channel, that remains so after a prolonged time span following the engineering study. The next large rainfall will no doubt cause flooding problems for us on the water’s edge.

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