Persistence of largemouth bass virus infection in a northern Mississippi reservoir after a die-off

Approximately 3,000 adult largemouth bass: Micropterus salmoides were found dead in September 1998 in Sardis Reservoir, Mississippi. Investigation of largemouth bass electrofished I month after the reported losses revealed a high level of infection with largemouth bass virus (LMBV) in the population . Subsequent sampling on five separate occasions during the following year revealed that approximately one-half of the fish were positive for LMBV 7 m onths after the die-off. On the last sampling, 13 months: after the die-off , approximately one-third of bass cultured positive for LMBV. The most comm on finding associated with LMBV infection was a yellow waxy substance in th e swim bladder that consisted of erythrocytes and eosinophils in a fibrin c lot indicating previous hemorrhage. In nearly every case, fish that had the swim bladder lesion cultured positive for LMBV. Predisposition to infectio n did not correlate with the gender or size of the fish. Sympatric white ba ss Morone chrysops, white crappies Pomoxis annularis, bluegills Lepomis mac rochirus, and gizzard shad Dorosoma cepedianum were also evaluated and foun d to be negative for LMBV. This study is the first report of a high level o f LMBV infection and long-term LMBV persistence in a largemouth bass popula tion in Mississippi and provides circumstantial evidence suggesting that th e largemouth bass-specific losses were LMBV associated.