An Ichthyophonus ‐typefungus in the deep‐sea pelagic fish Scopelogadus beanii (Günther) (Pisces: Melamphaidae)pathology, geographic distribution and ecological implications

• Published in: Journal of Fish Biology
• Main Authors: Gartner, J. V., Zwerner, D. E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1988
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; North Atlantic
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1988.tb05381.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1988.tb05381.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1988.tb05381.x

Parasitological examination of 400 specimens of the lower mesopelagic‐bathypelagic melamphaid fish Scopelogadus beanii (Günther) collected from throughout the species'geographic range in the Atlantic Ocean revealed cysts ranging in size from 1 to > 20 mm diameter in the livers of 50 individuals (12.5%). Histological preparations showed that the encysted material was an Ichthyophonus‐type fungus, which destroyed the liver tissue in infected individuals by progressive necrosis, the extent of which varied with cyst number and size. Infections were found primarily in individuals > 80 mm s.l . (size of sexual maturity in S. beanii ), with a significantly higher rate of infection among females. Liver weight was significantly reduced in infected fishes. Body wet weights tended to be lower in infected females. Fish from the western Atlantic showed a significantly greater prevalence of infection (17.0%) than those from either the eastern (1.1%) or South Atlantic (7.1 %). Within the western Atlantic, individuals collected from the slope waters of the Mid‐Atlantic Bight showed a significantly higher percentage of infected individuals than those collected from more northerly areas (27.8% v. 9.9%, respectively); regional variations may be accounted for by differences in habitat and diet of S. beanii among these regions. The high percentage of infected individuals in the western North Atlantic, coupled with the pathogenic nature of the fungus, suggests the possible loss of reproductively competent individuals from the population of this region.