October 5, 2002
Fish health and Pfiesteria investigations in the
Middle River.

The following summarizes on-going investigations during the past several weeks into harmful algal blooms (Pfiesteria). To date, there is no evidence of active toxicity from either of these organisms.

Middle River: Maryland DNR has sampled the river 4 times since September 17 in response to citizen reports of lesioned menhaden (primarily in the Frog Mortar Creek area) and Maryland Department of the Environments finding of large numbers of lesioned menhaden during routine sampling on September 9. Surveys have found high percentages of lesioned menhaden and Pfiesteria presence, although no evidence of active toxicity. Details are as follows:

DATE

% Lesioned Menhaden

Pfiesteria presence
(positive samples / total samples)

9/17

50% (Frog Mortar Cr)

 1 / 1

9/23

 71% (Frog Mortar Cr) 2 / 2

10/1

 Unable to collect fish (Frog Mortar Cr) 0 / 0

10/4

 Unable to collect fish, but observed approximately 25% of 1,000s of menhaden with ulcers
(Martins lagoon)		 Not yet available