Fish health assesments of Great Lakes coregonids

Abstract

Health of Great Lakes coregonids is continuously monitored for the spread of pathogens because of their economic importance. An infectious disease and parasite survey was conducted to build on previous data collected in the past but to also examine other factors that may affect distribution of pathogens in Great Lakes lake whitefish, round whitefish, and bloater populations. Coregonids (n=394) were collected from 3-4 regions in Lake Michigan, Lake Huron and Lake Superior and screened for target pathogens according to the procedures outlined in the AFS Blue Book Fish Health Section Inspection Manual. Parasite and age data were collected from a sub-sample (n = 2-30) of each fish species from each region sampled. No target viral pathogens were detected and one bacterial pathogen was detected in a lake whitefish from Western Lake Superior. A total of7,404 parasites were recovered representing 12 genera. Prevalence of infection ranged from 50% to 90% in each host species. Results indicate that host age and condition factor do not appear to influence the presence or absence of parasite communities of coregonids in the Great Lakes.