Investigation shows January fish kill at Faun Lake was due to algae bloom

In late January residents who live near Faun Lake in Venice notified Sarasota County about the occurrence of a large fish kill. Because herbicide had recently been applied on the bank, some were concerned that this might have been the cause, but testing showed that this was not the case. Two sets of water quality samples were taken and these were sent to certified laboratories for analysis of total suspended solids, specific conductance, pH, nutrients, fecal coliform, glyphosate, and six chlorinated herbicides.

The test results showed that herbicide was not present in the water, and a high dissolved oxygen level implicated the overgrowth of algae in the lake as the culprit. High dissolved oxygen is a characteristic of an algal bloom. The photosynthetic cycle of algal plants can cause abrupt swings in the dissolved oxygen levels of a water body, from very low oxygen to very high oxygen. Fish are unable to tolerate this sudden change and perish.

Sarasota County Parks and Recreation staff has consulted with the Fish and Wildlife Conservation Commission regarding re-stocking of the pond. It will be a few months off since they are locating approved fish nurseries and may have to wait until the fish "grow" or reach an appropriate size for release.