CHARLOTTETOWN -- The preliminary investigation into a Prince Edward Island fish kill this summer says disease has been ruled out as the cause.

The report released on Friday evening by the Department of Agriculture and Forestry says 1,155 fish were recovered out of an estimated 4,500 to 10,900 fish killed in the incident.

The fish were found along the banks of the North River near Springvale, P.E.I., on Aug. 6., and scientists estimated they had been surfacing over a three-day period.

The report says necropsy results from the Atlantic Veterinary College showed the fish had a "sudden, acute death."

The department says it is continuing its investigation and a final report on the cause of the fish deaths will be made public.