Presentation Abstract

Yersiniosis is a well documented disease that has largely affected salmonid farming and aquaculture. Caused by the bacteria Yersinia ruckeri, gram-negative and facultatively anaerobic, there has been little documentation of the condition in species beyond salmonids, and the direct inoculation of several non-salmonid species. Y. ruckeri is capable of living outside of a host for months at a time, is most severe at colder temperatures, and can be readily spread in captivity without relatively intense biosecurity. External symptoms often include loss of appetite, lethargy, loss of buoyancy control, darkening of the skin, hemorrhaging and ulceration in the fins and surrounding tissue, and exophthalmia. Internal hemorrhaging often occurs in the liver, kidney, and swim bladder, and the spleen becomes darkened and inflamed with translucent yellowish fluid accumulating in the lower intestine. It has now been shown that infected salmonids can be a vector for infection to other fishes in the same environment, as it has now been isolated from wild caught Yellowtail Rockfish (Sebastes flavidus) and Kelp Greenling (Hexagrammos decagrammus). The specific vector for the disease was identified as hatchery cultured Chinook Salmon (Oncorhynchus tshawytscha). The disease resulted in extremely high mortality rates in all three identified species, the highest being a 100% mortality rate among rockfish. In order to identify the bacteria, the primary methodology was the use of cultures on ribose ornithine deoxycholate agar and observations and necropsies comparing symptoms and anatomical changes of the three infected species to positively conclude the identity of the bacterial species. Isolations of the aetiological source were obtained successfully from one rockfish and one greenling, demonstrating the cross species infection without direct inoculation.

Session Title

Posters: Species & Food Webs

Keywords

Yersiniosis, Yellowtail Rockfish, Kelp Greenling, Chinook Salmon, Yersinia ruckeri, infection, cross species

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-110

Start Date

5-4-2018 11:30 AM

End Date

5-4-2018 1:30 PM

Type of Presentation

Poster

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 5th, 11:30 AM Apr 5th, 1:30 PM

Cross species infection of Yersinia ruckeri from chinook salmon (Oncorhynchus tshawytscha) to yellowtail rockfish (Sebastes flavidus) and kelp greenling (Hexagrammos decagrammus)

Yersiniosis is a well documented disease that has largely affected salmonid farming and aquaculture. Caused by the bacteria Yersinia ruckeri, gram-negative and facultatively anaerobic, there has been little documentation of the condition in species beyond salmonids, and the direct inoculation of several non-salmonid species. Y. ruckeri is capable of living outside of a host for months at a time, is most severe at colder temperatures, and can be readily spread in captivity without relatively intense biosecurity. External symptoms often include loss of appetite, lethargy, loss of buoyancy control, darkening of the skin, hemorrhaging and ulceration in the fins and surrounding tissue, and exophthalmia. Internal hemorrhaging often occurs in the liver, kidney, and swim bladder, and the spleen becomes darkened and inflamed with translucent yellowish fluid accumulating in the lower intestine. It has now been shown that infected salmonids can be a vector for infection to other fishes in the same environment, as it has now been isolated from wild caught Yellowtail Rockfish (Sebastes flavidus) and Kelp Greenling (Hexagrammos decagrammus). The specific vector for the disease was identified as hatchery cultured Chinook Salmon (Oncorhynchus tshawytscha). The disease resulted in extremely high mortality rates in all three identified species, the highest being a 100% mortality rate among rockfish. In order to identify the bacteria, the primary methodology was the use of cultures on ribose ornithine deoxycholate agar and observations and necropsies comparing symptoms and anatomical changes of the three infected species to positively conclude the identity of the bacterial species. Isolations of the aetiological source were obtained successfully from one rockfish and one greenling, demonstrating the cross species infection without direct inoculation.