Seasonality and the microhabitat of Microcotyle sebastis Goto, 1894, a monogenean gill parasite of farmed rockfish, Sebastes schlegeli Hilgendorf 1880

Abstract

A total of 353 farmed rockfish, Sebastes schlegeli Hilgendorf, 1880 were sampled from 3 localities on the Korean coastline over a 12 month period. Full parasitological examination revealed the polyopisthocotylean monogenean Microcotyle sebastis Goto, 1894 to be abundant with infections consistently reaching over 90~100% prevalence throughout the year. A seasonal pattern in parasite abundance on the gills is evident, with the population peaking twice, the largest in winter and again in summer. While the parasitic load on the left and right gills was not dissimilar, parasites within the gill sets were found to favour settlement on the Ⅱ and Ⅲ gill arches. A comparison of parasite abundance with host length, revealed that the smaller length fish classes (less than 17 ㎝ standard body length) had significantly heavier infections than those of larger fish (greater than 17 ㎝ standard body length). This report represents the first record of Microcotyle sebastis on farmed rockfish in Korean coastal waters.