title: Euryphorus brachypterus (Copepoda: Caligidae) on wild pacific bluefin tuna from the Tsugaru Strait, northern Japan.
abstract: Parasitic copepods infecting large scombrid fishes have been known for a long time because their hosts are economically important. Most studies, however, have focused on their morphology or their infection status in aquaculture from pathological viewpoints, and very few quantitative surveys have been conducted under conditions in the wild. This study therefore investigated the prevalence of Euryphorus brachypterus (Caligidae) in wild Pacific bluefin tuna (PBF). Results of sampling from August to September 2014 at the western area of the Tsugaru Strait, Japan showed that 13.2% of the PBF individuals (n = 1978) were infected with this copepod. The prevalence of infections was highest in larger fish but varied among landing dates, which were classified into three clusters and in all smaller fish, the prevalence of infections was zero. This suggests that E. brachypterus mainly uses the larger PBF, which becomes sources of further infections in other seas, and that at least two host populations with different infection statuses at the strait.
authors: Department of Aquatic Bioscience, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido 099-2493, Japan. Electronic address: minoru.kanaiwa@gmail.com.
authors: Minoru
authors: M
authors: Kanaiwa
authors: Department of Aquatic Bioscience, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido 099-2493, Japan.
authors: Yuki
authors: Y
authors: Yamamoto
authors: National Research Institute of Far Seas Fisheries, Fisheries Research Agency, 5-7-1 Orido, Shimizu-ku, Shizuoka, Shizuoka 424-8633, Japan.
authors: Yuko
authors: Y
authors: Hiraoka
authors: JANUS, 5F Nishi-shinjuku Kimuraya Bldg., 7-5-25, Nishi-shinjuku, Shinjuku, Tokyo 160-0023, Japan.
authors: Minoru
authors: M
authors: Kato
authors: Fisheries Systems Science Group, Faculty of Agriculture & SANRIKU Fisheries Research Center, Iwate University, 3-18-8, Ueda Morioka, Iwate 020-8550, Japan.
authors: Gakushi
authors: G
authors: Ishimura
authors: Graduate School of Environmental Earth Science, Hokkaido University, N10W5 Sapporo, Hokkaido 060-0810, Japan.
authors: Hirotaka
authors: H
authors: Katahira
mesh_terms: D000818:Animals; D017756:Aquaculture; D033342:Copepoda / Q000469:parasitology*; D005260:Female; D005393:Fish Diseases / Q000453:epidemiology / Q000469:parasitology*; D007564:Japan; D008297:Male; D014413:Tuna / Q000469:parasitology*
keywords: Caligidae; Epidemiology; Parasitic copepod; Thunnus orientalis