Abstract

Striped bass (morone saxitilis) is the most popular sport fish in the State of Maryland. Numerous stock assessment plans, sport and commercial fisheries cooperative projects and health assessment studies have been conducted to learn more about this important game species. Over the past few years the Maryland Department of Natural Resources Fish & Wildlife Health Program implemented plans to examine health status and to document the extent of mycobacterial infections in striped bass.

Mycobacteriosis in all species (i.e., humans and captive terrestrial mammals, birds, reptiles, amphibians) is a chronic, debilitating, wasting disease usually resulting in death if not treated with antibiotics. Since the distribution of mycobacterial infection in striped bass encompasses the entire Chesapeake Bay in Maryland and Virginia, overall mortality and infection rates are not known. Occurrence of infection is dependant on the health status of the individual, presence of natural and anthropogenic stressors and the general quality of the environment it inhabits. Estimates of prevalence of disease range from 25-60% in Chesapeake Bay resident striped bass populations. With varying suspected levels of infection, confusion has arisen as to the health of the striped bass population.

Affected striped bass are reported by citizens, charter boat captains, private organizations, and several state and federal agencies thus complicating reporting estimates. Fish are reported as emaciated, exhibiting external or internal lesions, or reported in any combination of these descriptions. Not all conditions can be directly attributed to mycobacterial infections. Physical injury from routine handling can disrupt the protective slime layer on fish skin and cause external injury. Skin infections alone are not evidence of mycobacterial infection. However, simple skin lesions once invaded by any pathogen can progress to diffuse skin lesions and may or may not lead to systemic disease.

Results of Maryland efforts and implications for future striped bass health and disease studies will be presented.