According to the New Hampshire Fish and Game Department, bass sampled this summer from Lake Winnipesaukee have tested positive for largemouth bass virus (LMBV), with initial testing showing LMBV to be present in a sample of smallmouth bass. The infected fish were collected as part of the Lake Winnipesaukee bass tagging study being conducted by the Department. Previously, LMBV had not been detected in the state. Fish and Game biologists have been testing for the virus since 2006.

What is largemouth bass virus? According to Dr. Joel Bader, N.H. Fish and Game Pathologist, LMBV is one of more than 100 naturally occurring viruses found in fish. "Finding largemouth bass virus in smallmouth bass is not surprising, as this virus is known to be carried by other fish, such as smallmouth bass, pickerel and some sunfish species as well," Dr. Bader said. "As we continue to test more bass from Lake Winnipesaukee, it is likely that we will also find the virus in largemouth bass." Largemouth bass virus is one of more than 100 naturally occurring viruses found in fish. However, fish species having largemouth bass virus are safe to handle and eat as the virus does not infect warm-blooded animals, including humans.

Largemouth Bass - Micropterus salmoides:  Averages 8-17 inches

According to Dr. Bader, the presence of the virus in a fish population doesn’t mean fish will develop the LMBV disease, which can cause them to die or show signs of being in poor health. Most fish carrying largemouth bass virus appear completely normal, but largemouth bass kills sometimes result in waters that test positive for LMBV. These fish kills generally occur during the summer months, indicating that warmer water temperatures may be a factor. In cases where the virus has triggered disease, dying bass may be near the water surface and have difficulty swimming and remaining upright. The virus attacks the swim bladder, sometimes causing bass to lose their equilibrium and appear bloated. Largemouth bass, between 12 and 15 inches in length, appear to be the most susceptible to the disease. The occurrence of lesions or black spots is not a sign that a fish has LMBV.

Doctor Bader, says that the virus appears to result in disease when largemouth bass are stressed from warm water temperatures, low oxygen, poor water quality and frequent handling.  Currently, scientists are unsure as to how the virus is transmitted or how it develops into a disease. There is currently no cure or preventative for LMBV, and it can live in the water for up to seven days. Dr. Bader, says that it is known that the virus may be transmitted through the water by fish consuming infected prey or through direct and indirect contact in boat live wells.

No evidence currently exists that this virus has caused long-term impacts to a fishery. Some data indicate that an infected fishery will recover over a period of years.

"Based on the information we have about this virus, it is unlikely that largemouth bass virus poses a serious threat to the long-term health of New Hampshire’s bass resources," stated Gabe Gries, New Hampshire Fish and Game Department’s fisheries biologist and Warnwater Project Leader. "However, because this virus can sometimes kill or negatively impact largemouth bass and can be spread or influenced by anglers, it is important to test fish to learn where the virus is present in New Hampshire waters, inform anglers about the virus and try to minimize its spread."

Gabe Gries stated that it is of utmost importance for anglers to help keep this virus from spreading by cleaning their equipment after use and by not transferring fish, including baitfish, from one water body to another.  To do this, Gabe offers the following suggestions:

1. Drain water from the bilge and live-wells and clean boats, trailers and other equipment between fishing trips with a solution of bleach to water (1 to 100 ratio) and let air-dry.

2. Use solution of bleach to water (1 to 100) to clean live wells and let air-dry.

3. Never transfer fish or fish parts from one body of water to another. New Hampshire law prohibits the transfer of live fish from one water body to another.

4. Do not release live bait into water bodies.

5. Handle bass as gently as possible.

6. During times of high water temperatures, minimize stress to fish as much as possible.

7. Conduct fishing tournaments during cooler weather, so that fish caught will not be as stressed.

8. Reduce daily bass tournament bag limits or use a "paper format" during times of high water temperatures.

9. Report dead or dying fish to the N.H. Fish and Game Department.

10. Educate other anglers about LMBV.

Dr. Joel Bader, stated "It is likely that the virus is, or will soon be, present in other water bodies in New Hampshire. We will soon be expanding our testing for this virus in other waters, and ask the public for their cooperation in reporting any fish kills, particularly those involving bass."

Largemouth bass virus was first detected in Florida in 1991 and gained national attention in 1995 when it caused a largemouth bass kill in South Carolina. The virus was originally thought to be restricted to the southern United States, but it has been recently detected in some Northeastern states, including Vermont (Lake Champlain) and Connecticut.

For further information on the largemouth bass virus, readers may contact: Dr. Joel A. Bader, Fish Pathologist, N.H. Fish and Game Department, 200 Main Street, New Hampton, N.H. 03256, phone: (603) 744-5470. You may also e-mail Dr. Bader at: jbader@nhfgd.org.