Investigations of Disease Factors Affecting the Declines of Pacific Herring211 Populations in Prince Willaim Sound. Restoration Project 98162. EXXON VALDEZ Oil 211 Spill Restoration Project Final Report

摘要

In spring of 1997 Viral Hemorrhagic Septicemia Virus (VHSV) prevalence was211u001esignificantly greater in fish from Prince William Sound (PWS) than from Sitka. A 211u001ehigh prevalence in PWS in 1998 was associated with a population decline in the 211u001espring of 1999. The prevalence of Ichthyphonus continued to decrease within the 211u001epopulation as a whole due to recruitment of younger fish with lower rates of 211u001einfection. The prevalence of Ichthyophonus in the 1988 year-class remained 211u001econstant at 26-30% over four years. Studies in PWS demonstrated that closed 211u001epounds play a role in transmission of VHSV to susceptible fish, resulting in 211u001erapid spread of virus and mortality within the pens. Ichthyophonus hoferi is 211u001econcluded to be a pathogen of herring but no evidence for its role in herring 211u001edecline in PWS is found. Likewise, no evidence for oil-related increased 211u001esusceptibility to VHSV was found in either wild or laboratory-reared herring.