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Seasonal Variation in the Incidence of Lymphocystis in the White Crappie from the Niangua Arm of the Lake of the Ozarks, Missouri
Author(s) -
Witt Arthur
Publication year - 1957
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1955)85[271:svitio]2.0.co;2
Subject(s) - incidence (geometry) , biology , fish <actinopterygii> , seasonality , veterinary medicine , fishery , zoology , ecology , medicine , physics , optics
Seasonal variation in the incidence of diseases or parasites in natural populations of fishes has not been documented. Seasonal variation in the incidence of lymphocystis in the white crappie, Pomoxis annularis, was determined from 5,906 fish collected in 1950–1951 and 1,593 fish collected during October 1952 through 1955. The incidence of the disease was greatest in July (10.7 percent), decreased in October (1.7 percent) and increased in November (6.9 percent). Over winter the incidence of the disease gradually decreased and reached a low in April (1.4 percent) after which it increased again. The tumors occurred on all parts of the body and fins but over 60 percent on the caudal fin. The disease was more prevalent in fish under 6.7 inches than in larger ones. In 1950–1951, 97 percent of the infected fish were less than 6.7 inches long. The 1949 year class was abundant during this study and its members carried the disease for a period of 3 years. The disease does not appear to be lethal to the white crappie; however, infected fish weighed 3 to 5 percent less than sound fish of the same length. Only one other fish, a walleye, was found to be infected.