John M. Grizzle

Largemouth bass virus (LMBV), a recently identified pathogen, affected largemouth bass (Micropterus salmoides) in the southeastern United States beginning in the 1990s. Concern about the impacts of this little-known pathogen on largemouth bass populations, effects on fisheries management, and the need to provide anglers and the media with consistent and accurate information prompted a private organization (Bass Anglers Sportsman Society) to invite managers and researchers from state and federal agencies and universities to a series of five annual public workshops beginning in 2000. These...

In 2004, the Southeastern Cooperative Fish Disease Project completed 40 years of research, education, and disease diagnosis in support of the fisheries management goals of the members of the Southeastern Association of Fish and Wildlife Agencies (SEAFWA). This project has been possible because of the cooperation of biologists and support from the Southeastern states. Major areas of research included parasites of warmwater sport fish, bacterial and viral diseases of fish, and environmental effects on fish health. These research topics arose from problems identified because of the disease...

The voltage gradients of electric fields produced by electrofishing boats are important in determining sampling efficiency and the potential for injuring fish. We evaluated 10 electrofishing boats and found that 3 boats had malfunctions that could impact sampling or operator safety. The in-water voltage gradients were measured for the remaining 7 boats to make comparisons among boats and to determine the voltage gradients present during electrofishing. For all boats evaluated, the cathode was the aluminum boat hull, and the 2 anode arrays each consisted of 3-11 droppers (cables, chains, or...

Human chorionic gonadotropin (HCG) is often used to induce spawning of fish. However, the U.S. Food and Drug Administration (FDA) has not approved HCG for use in fish because they claim additional efficacy data are required. Efficacy of HCG for spawning walleye (Stizostedion vitreum), was evaluated at 3 hatcheries for 3 years. During the 1993-1995 spawning seasons, 17.5% (54 of 308) of female walleyes spawned after a single injection of HCG. Of 253 females receiving a second injection, 92.1 % spawned for an overall spawning success of 93.2%. For females, a HCG dose as low as 330 IU/kg in...

Human chorionic gonadotropin (HCG) is often used to induce spawning offish. However, the U.S. Food and Drug Administration has not approved HCG for use in fish because they claim additional efficacy data are required. Efficacy of HCG for spawning striped bass (Morone saxatilis) and white bass (M. chrysops) was evaluated at 15 hatcheries in 10 states. For strip spawning of females, a single dose of HCG was effective for 90.2% of striped bass (N = 428) and 89.4% of white bass (N = 660). After strip spawning, hatching rates were 39.5% for striped bass and 26.1% for white bass. Of 90 striped...

Eight species of bacteria, 8 genera of parasites, and I species of virus were found infecting rainbow trout (Salrno gairdnen), brown trout (S. trutta), brook trout (Salvelinus jontinalis) and yellow perch (Perca jlavescens) from 2 locations in the Chattahoochee River below Buford Dam. There were no clinical signs ofdiseases caused by these potentially pathogenic organisms. Microscopic lesions were present in some of the fish, and the gill was the organ most often affected. These lesions were probably caused by a chemical in the water, but it was not possible to identify the chemical with...