First record of the non-indigenous parasitic copepod Neoergasilus japonicus (Harada, 1950) in the Lake Ontario Watershed: Oneida Lake, New York

Four specimens of the Asiatic parasitic copepod Neoergasilus japonicus (Harada, 1930) were collected from Oneida Lake, New York in September 2018; one specimen was from a white sucker Catostomus commersonii, another from a green sunfish Lepomis cyanellus, and two from a bluegill Lepomis macrochirus. The four adult female specimens were found attached to the base of the gills of their respective hosts along with other ergasilid species. The average total length of the adult female N. japonicus specimens we found was 0.609 mm. These detections represent the first known occurrence of this non-native species in the state of New York, extends the easternmost distribution of this parasite over 400 miles, and now includes the Lake Ontario watershed for the first time. It is commonly believed that the international aquaculture industry and aquarium fish trade are the most likely vectors of dispersal for N. japonicus. Monitoring the spread of non-indigenous aquatic species is an important step towards the development of management plans and mitigation efforts with regards to the anthropogenic causes of dispersal, and fish parasites are no exception.