Antoinette Clemetson, New York Sea Grant, (631) 727-3910
STONY BROOK, NY. November 18, 2009 - Researchers at the Marine Animal Disease Laboratory (MADL) at Stony Brook University have been taking a hard look at a fish disease in one of the region’s most significant species -both commercially and recreationally – the striped bass.
Mycobacteriosis is a disease that has traditionally been associated with fish being raised in aquaria. However, there has been a significant increase in its occurrence in wild fish over the years. Enzootic mycobacteriosis has been a potential threat to striped bass populations in the Chesapeake Bay for more than a decade, but these infections are also being observed in New York’s waters and those further north. Certain mycobacteria are ubiquitous in both fresh and marine environments, and include species pathogenic to marine animals and humans. Newly identified species such as Mycobacterium pseudoshotsii and M. schottsii were first detected in the Chesapeake Bay. Recent studies conducted by the Marine Animal Disease Lab (MADL) have isolated both bacteria in striped bass caught in marine waters around New York.
Research estimates more than 70 percent of the striped bass population that reside in several tributaries in the Chesapeake suffer from this infection. Infection levels are much lower in New York (approximately 20 percent of the population) and further north along the Atlantic coast. M. pseudoshotsii was consistently isolated from infections that occur in New York.
This disease can ultimately lead to mortality in a significant number of striped bass in Chesapeake Bay. Unfortunately, fish that suffer from the disease die slowly, making it extremely difficult to evaluate the full impact of this problem.
Clinical signs in fish include external ulcers and lesions (note: these symptoms are rarely being observed in fish taken in New York), swelling of the eyes, emaciation, skin color changes, and stunted growth. Alternatively, fish may not show visible signs at all. These symptoms are not unique to mycobacterial infections, and conclusive diagnosis must be conducted under a microscope.
Prolonged exposure to fish that carry the pathogen can lead to health risks in humans. These Mycobacterium species are closely related to another species that is known to cause “Fish Handlers’ Disease,” which is seen in people who regularly handle wet fish. Members of the public are urged to be on the alert for unusual symptoms that include sores (or lesions) that are painful and slow to heal, or swellings or rashes on the hands and lower arm.
How can members of our fishing communities minimize the exposure risk to harmful mycobacteria? Follow these simple tips:
- Take special precaution if your immune system is weak or compromised.
- Wear gloves when handling fish.
- Be particularly careful if you have open wounds or abrasions on your hands or arms.
- Return any fish with skin lesions to the water.
- Wash thoroughly with soap and water after coming in contact with fish or open water
- Properly cook fish before you eat the meal. (Seafood should be cooked until it reaches an internal temperature of 145°F for at least one minute.)
For more information, contact New York Sea Grant’s fisheries specialist Antoinette Clemetson at (631) 727-3910.
The Marine Animal Disease and Pathology Laboratory (MADL), a consortium of the School of Marine Atmospheric Sciences (SoMAS) at Stony Brook University, NYS Dept. of Environmental Conservation, Cornell University and New York Sea Grant, is funded by the NYS Legislature to conduct diagnostics and research into the causes and effects of disease and pathogens in marine fisheries. Other partners include Long Island University, NYS Dept. of Health and NYS Dept. of Agriculture and Markets.