Large Mouth Bass Virus Update

The Largemouth Bass Virus has been confirmed in all four of the fish sent to MSU’s Fish Health Laboratory. The virus is very likely the cause of the high adult bass mortality observed on the Main Lakes that peaked in early to mid August. We at Summit Laboratory are not authorities on this virus and therefore are promoting and adhering strictly to Michigan DNR recommended courses of action. These actions are as follows and have been taken directly from the MDNR website:
“The DNR concurs with recommendations from the LMBV Workshops, and reminds anglers and boaters to take the following steps to help prevent the spread of the virus:
· Clean boats, trailers, other equipment thoroughly between fishing trips to keep from transporting LMBV, as well as other undesirable pathogens and organisms, from one water body to another with special care to clean fishing equipment when you are done fishing known locations of the virus.
· Do not move fish or fish parts from one body of water to another, and do not release live bait into any water body.
· Handle bass as gently as possible if you intend to release them and release them as quickly as possible.
· Refrain from hauling the fish for long periods in live wells if you intend to release them.
· Minimize targeting of largemouth bass during the period from mid-July to mid-August, especially during exceptionally hot weather conditions.
· Report dead or dying adult largemouth bass fish to Michigan Department of Natural Resources Fisheries Division offices.
· Volunteer to help agencies collect bass for LMBV monitoring.
· Educate other anglers about LMBV.
The disease usually causes mortality when fish are most stressed. Potential stressors include very hot weather, high angling pressure, and possibly aquatic weed or other treatments during very hot periods. Any measures that can be taken to minimize stress on these fish will reduce the impact of the disease and mortality.”
The MDNR will be notified of the existence of the virus in the Main Lakes. The LMBV has most likely been in the lake(s) for years and is likely to remain as long as there are sunfishes (bass family) and amphibians to host the virus. The original source of the virus reaching the Main Lakes is not possible to determine but could have been: fish stocking, unintentional angler introduction, amphibian migration, shore birds etc. There is no documented health threat to humans from swimming, contact or consumption of fish. Of the three stresses that cause fish mortality from the virus: Fishing Pressure, Herbicide Applications, and Temperatures exceeding 77 degrees F, it was temperature that was most extreme when compared to past seasons. We may observe similar high mortality periods in the future (especially during very hot years) but please keep in mind this mortality involves a small percentage of the bass population and we expect to see little impact on the quality of the CL bass fishery given the DNR recommendations are followed and extreme heat does not become and annual occurrence.
We are taking direction from the DNR on this matter. Recommendations we support and state in our notices are only those of the DNR. The DNR does not support an official moratorium on bass fishing during months where water temperatures exceed 77 degrees. Licensed anglers have the DNR granted right to fish for bass and all other in-season species in CL during times when the water temperature exceeds 77 degrees. Summit Laboratory however does support all efforts to ensure anglers targeting bass during high water temp months do so with the full knowledge of the presence of the virus and associated DNR recommendations. In addition to the educational effort, we support moving the annual bass tournament out of July and or August and considering the reduction of time duration of the tournament. We would like to thank the Canadian Lakes Fishing Club for collecting and delivering the fish samples required. If you have any questions, comments or concerns, please use the link provided to post them on this page. Your Lake Managers, Joel Steenstra and Tom Krueger