Treatment of a laboratory-based model of shell disease in hatchery raised American lobsters (Homarus americanus)

Epizootic shell disease in American lobsters, Homarus americanus H. Milne-Edwards, 1837, has been of special concern since the mid-1990s due to its impact on fisheries. Numerous studies have led to the present understanding that this disease has a polymicrobial etiology. However, lacking in this research is exploration of the potential ways to ameliorate the disease. This is particularly important for public aquariums that have a strong focus on aesthetics and animal health. We performed two experiments to test short-term treatment methods on a laboratory-based model of shell disease on juvenile American lobsters. A preliminary experiment tested the effects of Hikari® Biobandage, a commercially available product used for treating fish lesions, on early- and late-stage shell disease. Another experiment examined resulting shell disease when lobsters were treated with distilled water, 10% povidone-iodine, d-alpha-tocopherol acetate (Vitamin E oil), formalin (100 ppm), and malachite green (5 ppm). We monitored the development of shell disease in both nonfacilitated and facilitated (in which the shell was damaged to induce disease) areas of the shell to determine effectiveness up to ecdysis. Biobandage was not effective at limiting nonfacilitated shell disease or facilitated wounds. Fresh water exacerbated facilitated wounds in comparison to animals treated with povidone-iodine, formalin, and malachite green. Formalin and malachite green treated lobsters showed the lowest severity of nonfacilitated shell disease. The study also showed that frequent handling alone (lobsters in control group) exhibited a higher amount of nonfacilitated shell disease. Identifying effective treatments in captive lobsters may provide unique solutions for studying shell disease.