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 Q & A SessionContinued from The Largemouth Bass VirusDodson: Where did the virus come from and how is it transmitted? Texas Parks and Wildlife: It was first documented in 1995 and we have no idea how it got to Texas or how it seems to skip from one lake to another. Similar viruses have been reported in some aquarium species in California (guppies, etc.), so it may have been brought in by bait supplies-minnows, etc. It is not impossible that areas with close contact between fish such as live wells could conceivably result in passage from fish to fish since we assume it infects fish either orally (gills or in food) or by skin contact. Dodson: All of these ideas are reasonable, except that it is impossible for me to envision how an introduced food source could spread over the entire take to induce disease at the same time and in only one species of fish. The livewell concept is a scary one, but usually people don't keep bass on Fork and only in limited numbers of tournaments after which they would be released. This doesn't have to be a new virus, but rather as with many new diseases simply popped to the surface by finding a host that it finds to its liking and eventually kills. There are numerous viruses that are carried by hosts without greatly threatening the host and some that only become activated under certain conditions, and when in the right species of animal. How was the virus diagnosed? Texas Parks and Wildlife: The samples were sent to the vet school lab at Texas A&M University for analysis by electron microscopy. This data was negative, but was a reasonable first approach. The technique is quite restrictive in that they were looking for the scattered virus rather than using Biotechnology techniques, which would be much more sensitive. These types of bioassay tests were the ones conducted by Auburn University that confirmed the virus was present. Dodson: With this event, a further emphasis should be placed on developing a state-of-the-art molecularly biology section to serve as diagnostic support, but also genetic data actions needed to give better tools to fisheries and wildlife management folks in the next century. Fishing and hunting are major sources for the state and should be treated as a priority industry. Did the bass die from effects of pollution? Texas Parks and Wildlife: No direct correlation has been determined. Dodson: While our lakes and watersheds are increasingly more at risk from pollution, it should affect other species not just bass. What effects did stress have on the die off? Texas Parks and Wildlife: I get stressed just hearing this overused term, but in reality stress can weaken the immune system in any animal and an inherent dormant virus can become active. An example is a fever blister. The cause virus that lives in infected humans activates when we have a trigger effect. This could be from the effects of a cold or even an event such as severe sunburn or wind-blown drying the lips. The virus causes the sore then it goes away and lurks in body ready to emerge again. In the case of both Rayburn and Fork the fish died much after the major biological stress period post-spawn and thus were in a time of more stable survivability, the summer and fall. In the case of Fork, the initiation the die-off occurred when the water was considerably cooler than the previous year and the lake was full. Dodson: Have water samples been tested for the virus? Texas Parks and Wildlife: No! Dodson: Have baitfish such as shad or even parasites that attach to the bass been tested? Texas Parks and Wildlife: No! Dodson: I still can't figure out what could carry the virus and spread it over the entire lake. It makes no sense that there are enough free virus in a body of water so that they can spread upstream and into the backs of even the smallest cove. It also doesn't make sense that if a good source exists as a carrier in that the smaller fish would also not be a target. Insects can carry viruses, but the grasshopper swarm that covered east Texas occurred after the die-off began and while the catfish enjoyed their presence on the lake no catfish appeared to be dead from eating them on any of the lakes. What happens after such a viral infection? Texas Parks and Wildlife: Re-occurrences of die-offs didn't seem to occur in some of the southeaster lakes, but the potential exists. Dodson: Check the tournament weights on Rayburn in the spring of 1999 following the 1998 die-off. There was a major loss of five-pound plus fish. See how many 20-pound limits you find from weigh-in before and after the die-off. Present reports indicate the smaller bass population may be expanding, but it will be interesting to see what happens in the next two to three years. As far as Lake Fork is concerned the hope is that the die-off ends. The question then becomes what is left of the fishery? If something hasn't happened to the smaller bass, why didn't they school this summer and why were reports in the papers from some of the guides on the lake noting catches of six to eight fish per day? Does the virus affect Northern strain bass, or are the die-offs occurring in lakes with predominant Florida infusions? Texas Parks and Wildlife doesn't know if native bass are immune. Texas Parks and Wildlife: It most likely isn't linked to Florida strain because they have been around a considerable time as stockers in Texas and also no one has reported bass kills in Florida. This may well be a virus that has mutated and jumped species, or somehow activated in affected bass of a certain age. I have tried to give an overview of the agency's response to a series of hard questions. I have also given you my observations and ideas as a fisherman who stayed on top of this one, and as a scientist. After having said that, I share the frustration with Texas Parks and Wildlife officials that there is so much we don't know. There are some things that I can state explicitly. While some spokesperson in the Texas Parks and Wildlife played "pass the blame to fishermen" for the Raybum event I got a different and rational discussion from both Dr. McKinney and Mr. Jones concerning Fork. They know we have a problem and weren't afraid to say, "We don't know," to my questions. There was a coming together at Fork of fishermen, merchants and state agencies to try to determine the cause of the die-off. I wish I could tell you this is all behind us and Conroe isn't happening and Toledo Bend, downstream from Fork and 20-plus miles from Rayburn, is safe. But the time for "sugar coating" and providing "snow jobs" should be behind us. Fishermen, and concerned citizens, should be ready to do what ever we can to support guys like Dr. McKinney and Mr. Jones and other fisheries biologists who are trying to figure out the source of the virus and ways to control it. We may be in deep trouble since finding the source may be the only reasonable "cure." In the meantime, we can hope survivors in the lakes develop immunity to the virus and that they pass that immunity to their offspring.  LMBV Notes LMBV Information LMBV In Michigan Lake Fork Revisited LMBV and Chemicals Scientists Discuss LMBV Largemouth Bass Virus Facts Largemouth Bass Virus 2001 Update Largemouth Bass Virus 2002 Update Federal Grants Awarded to Study Largemouth Bass Virus |
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