Evaluating environmental pathogen abundance in relation to British Columbian salmon farms
Presentation Abstract
Although, there is evidence that salmon farms alter the seasonal, as well as absolute, abundance of parasitic sea lice, increasing the risk of infection to wild juvenile salmon. However, it is not known how salmon farms influence the distributions of viral and bacterial pathogens in the environment. In order to address this question, we genetically screened seawater samples, collected near active and inactive salmon farms inside Vancouver Island, British Columbia, for 30 viral and bacterial salmon pathogens, to assess the risk of juvenile salmon infection while they migrate past active salmon farms. We found that the probability of encountering a pathogen was significantly higher in the vicinity of active salmon farms when compared to inactive sites. In addition to contributing directly to observed pathogen distributions, active salmon farms were associated with elevated levels of herring DNA, which was also found to be an important factor influencing the distribution of pathogens in the environment. The results of this research suggest that fish farms increase the likelihood that juvenile salmon will encounter an infectious agent during their outward migration and this is partially attributable to increased aggregations of wild fish near active salmon farms. Due to their complex life-history, it is often difficult to identify the most pressing threats to wild salmon. This methodology represents a promising new avenue for monitoring disease risk, as it allows us to characterize the environmental hazards that wild salmon encounter during their migration and will complement traditional disease monitoring methods.
Session Title
The Impacts of Open Net Pen Salmon Farming on Wild Salmon
Conference Track
SSE11: Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2018 : Seattle, Wash.)
Document Type
Event
SSEC Identifier
SSE11-157
Start Date
4-4-2018 2:00 PM
End Date
4-4-2018 2:15 PM
Type of Presentation
Oral
Genre/Form
presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Pacific salmon fisheries--Salish Sea (B.C. and Wash.); Salmon--Pathogens--Salish Sea (B.C. and Wash.); Pathogenic microorganisms--Detection--Salish Sea (B.C. and Wash.); Branchiura (Crustacea)--Salish Sea (B.C. and Wash.)
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
Evaluating environmental pathogen abundance in relation to British Columbian salmon farms
Although, there is evidence that salmon farms alter the seasonal, as well as absolute, abundance of parasitic sea lice, increasing the risk of infection to wild juvenile salmon. However, it is not known how salmon farms influence the distributions of viral and bacterial pathogens in the environment. In order to address this question, we genetically screened seawater samples, collected near active and inactive salmon farms inside Vancouver Island, British Columbia, for 30 viral and bacterial salmon pathogens, to assess the risk of juvenile salmon infection while they migrate past active salmon farms. We found that the probability of encountering a pathogen was significantly higher in the vicinity of active salmon farms when compared to inactive sites. In addition to contributing directly to observed pathogen distributions, active salmon farms were associated with elevated levels of herring DNA, which was also found to be an important factor influencing the distribution of pathogens in the environment. The results of this research suggest that fish farms increase the likelihood that juvenile salmon will encounter an infectious agent during their outward migration and this is partially attributable to increased aggregations of wild fish near active salmon farms. Due to their complex life-history, it is often difficult to identify the most pressing threats to wild salmon. This methodology represents a promising new avenue for monitoring disease risk, as it allows us to characterize the environmental hazards that wild salmon encounter during their migration and will complement traditional disease monitoring methods.
