Grand Lake St. Marys Fish Tissue Study Underway

            The state has begun a study at Grand Lake St. Marys to determine if high levels of an algal toxin called microcystin accumulates in fish tissue.

            The study will allow Ohio EPA scientists to determine whether to lift the existing “do not eat” fish consumption advisory, keep it in place or modify it to recommend eating a limited number of fish per month from the lake.

            The first fish samples were collected by Ohio Department of Natural Resources staff in October.  They have been preserved and will be compared to fish samples that will be taken from the lake in April, June and August 2011, to determine if extremely high levels of microcystin recorded in the lake pose a long-term health risk to humans who consume the fish.

            The state issued a “do not eat” advisory for fish taken from Grand Lake St. Marys last summer after microcystin levels in the water spiked to more than 2,000 parts per billion (ppb).  Microcystin above 20 ppb is considered high risk to humans for recreational contact, such as swimming and water skiing, by the World Health Organization.

            Other studies on microcystin in fish tissue indicate there is no significant bioaccumulation when fish are exposed to lower levels of the toxin. However, these studies did not look at the effects of microcystin at the extremely high levels recorded at Grand Lake St. Marys last summer.  The state issued the “do not eat” advisory as a precaution until actual fish tissue data is available.

            The current consumption advisory may be revised or lifted as early as this winter after tissue from the October fish collection is analyzed. The complete study will allow the state to make a more informed decision about future fish consumption advisories at Grand Lake St. Marys and other Ohio lakes that may experience high algal toxin levels.

            A report on the study is expected late next year. The $58,500 study is funded by the state.