Infection Status of Ayu and Other Wild Fish with Flavobacterium psychrophilum and Edwardsiella ictaluri in the Tama River, Japan

Hisato Takeuchi; Motoyuki Hiratsuka; Hiroki Oinuma; Yoshiyuki Umino; Daiki Nakano; Mayu Iwadare; Ryuji Tomono; Kazutomo Hori; Toshihiro Imai; Takanori Ishikawa; Aki Namba; Noriyuki Takai; Takehiro Ryuu; Hiroshi Maeda; Toshihiro Nakai; Nobuhiro Mano

doi:10.3147/jsfp.51.184

Research Articles

Infection Status of Ayu and Other Wild Fish with Flavobacterium psychrophilum and Edwardsiella ictaluri in the Tama River, Japan

Hisato Takeuchi, Motoyuki Hiratsuka, Hiroki Oinuma, Yoshiyuki Umino, Daiki Nakano, Mayu Iwadare, Ryuji Tomono, Kazutomo Hori, Toshihiro Imai, Takanori Ishikawa, Aki Namba, Noriyuki Takai, Takehiro Ryuu, Hiroshi Maeda, Toshihiro Nakai, Nobuhiro Mano

Author information

Hisato Takeuchi
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Motoyuki Hiratsuka
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Hiroki Oinuma
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Yoshiyuki Umino
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Graduate School of Biosphere Science, Hiroshima University
Daiki Nakano
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Mayu Iwadare
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Ryuji Tomono
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Kazutomo Hori
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Toshihiro Imai
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Takanori Ishikawa
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Tochigi Prefectural Fisheries Experimental Station
Aki Namba
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Research Fellow of the Japan Society for the Promotion of Science
Noriyuki Takai
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University
Takehiro Ryuu
Tokyo Metropolitan Islands Area Research and Development Center of Agriculture, Forestry and Fisheries
Hiroshi Maeda
Tokyo Metropolitan Islands Area Research and Development Center of Agriculture, Forestry and Fisheries
Toshihiro Nakai
Graduate School of Biosphere Science, Hiroshima University
Nobuhiro Mano
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University

Keywords: Flavobacterium psychrophilum, bacterial cold-water disease, Edwardsiella ictaluri, epidemiology, wild fish, Plecoglossus altivelis, ayu

JOURNAL FREE ACCESS

2016 Volume 51 Issue 4 Pages 184-193

DOI https://doi.org/10.3147/jsfp.51.184

Details

Abstract

The Tama River is an urban river flowing throughout the Tokyo Metropolis. The water quality has been improved and a large number of wild ayu Plecoglossus altivelis migrate upstream in recent years. We conducted an epidemiological survey on two fish pathogens, Flavobacterium psychrophilum and Edwardsiella ictaluri, among ayu and other wild fish species based on PCR and culture methods at four sites (lower-, middle-, upper-reaches and tributary) in the Tama River basin from May 2011 to November 2012. F. psychrophilum was detected in 15 fish species including ayu throughout the survey period, and the occurrence of F. psychrophilum infection (bacterial cold-water disease) among ayu was observed in upper-reaches and tributary areas between mid- and late June of both years. On the other hand, E. ictaluri was detected in 7 fish species mainly in summer and late fall of both years, and E. ictaluri infection of ayu with mass mortality occurred in the tributary area in late August 2012 only. It is speculated that the unusually high water temperature during August 2012 (approximately 6°C higher than that of 2011) served as a predisposing factor in this mortality. Disease occurrence in riverine ayu might be attributable to the subclinical infection status of fish and stress conditions imposed by the environment.

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