If you find a fish kill

Please contact the Massachusetts Environmental Police to report a fish kill.

Massachusetts Environmental Police Main Office


Emergency 24/7 Statewide Dispatch

The Details

How to report

To report a fish kill, please contact the Massachusetts Environmental Police Radio Room at 1-800-632-8075.

More info

The vast majority of fish kills turn out to be caused by a natural event. However, it’s important for biologists to rule out other causes including pollution. Natural fish kills are generally the result of low dissolved oxygen levels (anoxia), spawning stress or fish diseases. Dissolved oxygen depletion is one of the most common causes of natural fish kills. This can be the case at any time of the year but generally occurs during severe winters or late spring/early summer.

Winter Fish Kills

Thick ice and heavy snow cover can result in low dissolved oxygen levels in ponds. With increasing ice and snow packs there is less light penetration through the water column. This alters chemical and biological processes, often resulting in a winter fish kill.

Spring and Summer Fish Kills

As temperatures increase, the water cannot hold as much oxygen as when it was cold. Aquatic plants also increase their oxygen consumption. In turn, oxygen levels in shallow, weedy ponds decrease. If levels fall below that required for fish to survive, it can become critical. Late spring and early summer is also when most warmwater fish species begin to spawn. Large numbers of these species crowd in the shallow waters along the shore vying for the best spawning sites. These crowded areas are susceptible to disease outbreaks. The result is an unavoidable natural fish kill, usually consisting of one or two species of fish. This is a natural occurrence and does not pose a public health risk.


Massachusetts Environmental Police Boston HQ
251 Causeway Street, Suite 101, Boston, MA 02114

Emergency 24/7 Statewide Dispatch

MEP Boston FAX (617) 626-1670

MEP Boston

1 Rabbit Hill Road, Westborough, MA 01581

8 a.m.– 4:30 p.m., M-F

(508) 389-7890


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