Assessment of the 2004 Striped Bass Die-off at Lake Norman, North Carolina
North Carolina Wildlife Resources Commission,
Summer mortality is a concern for managers of reservoir striped bass fisheries across the southeastern United States.
The mortality is typically attributed to the lack of cool,
oxygenated water available to striped bass during summer months,
commonly referred to as the �habitat squeeze�.
However, in the late summer of 2004, the largest reservoir striped
bass die-off ever observed in North Carolina occurred at Lake Norman
despite the availability of suitable habitat.
A total of 2,497 dead striped bass were collected over a 22-day
This die-off resulted when a group of fish became trapped in the hypolimnion by an anoxic metalimnetic layer.
The trapped striped bass were initially in water that had cool
temperatures, forage, and sufficient oxygen.
Over the following
weeks, mortality occurred as hypolimnetic dissolved oxygen levels
decreased through normal biological processes.
A review of dissolved oxygen data from previous years indicated that
similar pockets annually form in Lake Norman, but have not resulted
in striped bass mortality.
However, circumstantial evidence suggests this may be the mechanism
for fish kills in other deep-water reservoirs and begs the question:
How often might similar Striped Bass kills occur?