On August 6, 2008 the largest fish kill on the Pamlico River in over a decade occurred between the Whichards Beach area and Broad Creek. Over 3.9 million fish, primarily juvenile menhaden were found floating within the channel and along the north side of the river.

Preliminary lab results from the State Division of Water Quality revealed an unnaturally high number of a toxic dinoflagellate called Karlodinium.

This plant-like dinoflagellate releases a toxin, called Karlotoxin that damages the gills of fish, and can basically cause them to suffocate. Since the kill consisted of mainly juvenile menhaden, which are filter feeders, the death is more likely associated with the toxin. Low oxygen levels would have produced a kill with multiple species of fish, not just menhaden. Conditions appeared to have been ideal for the karlodinium organisms to bloom and out compete other species of algae.

Karlodinium was also associated with a subsequent fish kill of close to 1000 menhaden on August 15 along the Washington Park waterfront.