Disease-translocation across geographic boundaries must be recognized as a risk even in the absence of disease identification: the case with Australian Sardinops

摘要

In 1995 and 1998/99 single species mass mortalities of sardine/pilchard Sardinops sagax (Clupeidae) spread rapidly throughout this species' range in Australia from the central coast of South Australia, dramatically decreasing the population size and representing the two most extensive mass mortalities recorded for marine organisms. The behavior of each epizootic indicated that an exotic pathogen was responsible, with the fatal agent shown to be a previously unknown herpesvirus. The focal origin of both events from a limited region within the extensive Australian range of S. sagax was not random. Tuna (Thunnus maccoyii) feedlots located in the same region as the epizootics' origins are responsible for delivering to the marine environment the largest quantities of S. sagax imported into Australia, which provides qualitative evidence of a link between the two events and imported S. sagax. This link provides an example of the need to undertake a review of the current international standards for import risk analysis (IRA) that requires a disease to be identified before it can be considered a risk. Regardless of the identity of the disease agents responsible, case histories of mass mortalities need to be given due consideration in both deciding whether to instigate an IRA and also form part of the IRA. Identification of a hazard should thus not be restricted to dealing only with identifiable diseases, but should also embrace case histories of epizootic events linked to (a) previously unidentified pathogens and (b) translocation of particular species between geographically separate populations. [References: 40]