Sept. 19, 2008
Vol. 38, No. 430

For more information, contact Craig Shirey, Fisheries Section, Division of Fish and Wildlife, 302-739-9914; Robin Tyler, Division of Water Resources, 302-739-9942; or Melanie Rapp, Public Affairs, 302-739-9902.

                 Fish Kill Involving Menhaden Reported in Torquay Canal in Rehoboth Bay

REHOBOTH BAY, Del. - A fish kill involving approximately 550,000 juvenile Atlantic menhaden was discovered this week in Torquay Canal, a deep circular dead-end lagoon upstream from the mouth of Bald Eagle Creek, located at the head of Rehoboth Bay.

“The likely cause of the fish kill was a combination of extremely low dissolved oxygen in the water and weather conditions that resulted in the rise of hydrogen sulfide at the bottom of Torquay Canal to the surface where fish were concentrated.” said Fisheries Manager and Fish Kill Coordinator Craig Shirey.

DNREC Division of Water Resources has water monitoring equipment in Torquay Canal which automatically measures dissolved oxygen every 15 minutes. Data show that very low dissolved oxygen levels have occurred in the canal all summer – especially at night and in the early morning.

“Water monitoring has been done in Torquay Canal for the past several summers, and the results indicate that very low dissolved oxygen is an annual pattern,” said Dr. Robin Tyler, environmental scientist with the Division of Water Resources. “We also know that hydrogen sulfide occurs in the deeper water of the canal and under certain weather conditions, it can rise to the surface.”

This week’s fish kill involving juvenile menhaden was the second to occur in Torquay Canal in the past month. In late August, 5,000 -10,000 menhaden died under similar conditions of low dissolved oxygen and weather conditions.

Torquay Canal and adjacent Bald Eagle Creek have a long history of fish kills due primarily to poor water circulation and unnatural deep areas throughout the waterways.  Large numbers of young menhaden are often affected, as they travel in large schools and feed on the abundant plankton and algae found in the canal. 

To report a suspected fish kill, please call 302-739-9914 from 8 a.m. to 4:30 p.m., Monday through Friday and 800-523-3336 weekends and after hours. Please provide locations, and if possible, an estimated number of fish involved and species, if known.