PREVALENCE, RELATIVE ABUNDANCE, AND MEAN INTENSITY OF PLEROCERCOIDS OF PROTEOCEPHALUS SP. IN YOUNG STRIPED BASS IN THE SACRAMENTO-SAN-JOAQUIN ESTUARY

Up to 79% of larval and juvenile striped bass, Morone saxatilis, in th e Sacramento-San Joaquin Estuary harbor plerocercoids tentatively iden tified as Proteocephalus sp. Histological slides of infected striped b ass revealed cysts encapsulating plerocercoids but no other host react ion. Prevalence of plerocercoids varied significantly among years and increased with striped bass length. Two copepods, Sinocalanus doerri a nd Eurytemora affinis, eaten by striped bass harbor a procercoid and a re probable vectors. However, copepod abundance in the estuary and in the diet of striped bass was not consistently correlated with prevalen ce of plerocercoids in striped bass. Plerocercoid prevalence correlate d significantly with water temperature and transparency but not with r iver outflow or electrical conductivity.