Disease Risks Posed by Hatchery Salmon

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1 Disease Risks Posed by Hatchery Salmon James Winton US Geological Survey Western Fisheries Research Center Seattle, Washington

2 Disease in Populations of Wild Fish Disease is a component of natural mortality in all ecosystems Features of the host, pathogen and environment determine the ecology of fish disease Limited understanding of disease in populations of wild fish Most diseases of wild fish are caused by endemic pathogens Fish in normal ecosystems are typically in balance with disease Severity of disease may increase when conditions change Explosive outbreaks may follow first encounter with a new pathogen The role of hatcheries in the ecology of disease in natural populations of fish is poorly studied

3 Potential Disease Risks Associated with Salmon Hatcheries Introduction of exotic pathogens Amplification of endemic pathogens Release of infected fish that contact wild stocks Provide a source of infection at unnatural times Alter frequency of genes associated with resistance Release of susceptible fish that amplify disease in wild Introduction of pollutants or stressors to ecosystem From Naish et al. 2008

4 Introduction of Exotic Pathogens Greatest threat to native, wild and free-ranging fish Often associated with public hatcheries or private aquaculture facilities Movement of live, infected fish or eggs between watersheds Use of raw fish or fish products as food Other pathways also important Movement of baitfish by anglers Ballast water Migratory fish Whirling disease and gyrodactylus are examples

5 Whirling Disease

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7 Yearling Class Strength in Madison River ( ) YEARLINGS / MILE Whirling disease introduced in 1987

8 Amplification of Endemic Pathogens Second greatest threat to native or wild stocks Involves pathogens already in system (typically maintained among wild fish) Hatcheries can produce very high levels of pathogens Hatchery fish can also provide selective pressure on endemic pathogens (e.g. adaptation to new species) Stability of pathogen and exposure history of wild stocks are important factors Sea lice and infectious hematopoietic necrosis virus are examples

9 Infectious Hematopoietic Necrosis Virus in Steelhead U Upper region - Alaska, British Columbia and Washington. Mostly sockeye salmon M Middle region - Hagerman Valley, Idaho extending into lower Columbia River Basin. Mostly rainbow and steelhead L Lower region - Sacramento River Basin, coastal rivers of Northern California and Southern Oregon. Mostly affects Chinook

10 R6 RBdn3 A16AWn3 A40W11n37 A20 A21Wn2 A22 A41 W15n2 W18n3 A26n2 W21 W1n2 W57 Bk Bl W80n2 W83 A12ABn6Jp A13 A42 R24 R39 R42Wn3 A30 A38n2 A34 W19ABWn26 LR73Rns W10 A23Wn5 Bsn3 W68W76 R7 RB1WRSOCn26 RB76 S29 O99 FF11 FF12 FF14 FF7n2 FF2 FF85FF17 IHN Virus Phylogeny Kurath et al U genogroup Maximum diversity 3.0% Sockeye, chinook, steelhead FRref FF51 ITref LR80RSn9 S20pFF90 FF52 FF84RBr FF18 FF19n2 S49_ FF86 FF88 FF152 FF178 FF25n2 FF35n2 FF4n3 S21 FF21 FF6 FF3n2 FF5n2 R3RWn3 R5 FF10n3 FF191 CST WRACFFn6 HO7 FF53 FF104 FF177 FF136n3 FF114n2 M genogroup Maximum diversity 7.6% Rainbow trout steelhead C9COn4 C2 SRCV C18 C11n7 C13n8 C10n7 C25 C1pOn2 C7n2 Col80 Col85 L genogroup Maximum diversity 3.3% substitutions/site Chinook, steelhead

11 IHNV in the Columbia River Basin M group virus U group virus Garver et al. 2004

12 M-type IHNV in Olympic Peninsula Steelhead 2009 Bogachiel Hatchery Steelhead adults 2010 Hoh River Wild Steelhead adults u 2007 Salmon River Hatchery Steelhead juveniles Lake Quinault Netpens Steelhead adults, yearlings Skookumchuck, Bingham Creek, Satsop, Lake Aberdeen, Humptulips Steelhead adults, juveniles, yearlings

13 Release of Infected Fish that Contact Wild Stocks Infected animals released by hatcheries can associate with native or wild stocks Hatchery fish may have higher intensity or prevalence of infection that native fish These animals may provide greater source of infection than typically present in natural systems Some activities (e.g. collection facilities at dams or barging) can increase stress and opportunity for contact Bacterial kidney disease and infectious hematopoietic necrosis virus are examples

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15 Provide a Source of Infection at Unnatural Times Fish in hatcheries can maintain some infections for a prolonged period Hatcheries may rear species or developmental stages that are different from the natural system Release of such fish or the hatchery effluent may provide source of infection for wild fish at times or life stages not typical of nature Infectious hematopoietic necrosis virus may be example

16 Source of infections at abnormal times or life stages Box Canyon Facility Clear Springs Foods, Inc Photo: courtesy of Scott LaPatra IHNV is present yeararound in the commercial aquaculture hatcheries of the Hagerman Valley of Idaho Steelhead reared in the region may acquire IHNV infections before outplanting as smolts

17 Alter Frequency of Genes Associated with Resistance Hatchery programs may use stocks having differences in disease resistance from wild stocks Hatcheries can exert (sometimes intense) selection Positive selection from large outbreaks Relaxed selection by disease avoidance Disease resistance may be reciprocal Interbreeding with hatchery fish may alter frequency of genes or alleles associated with disease resistance in the wild stock Ceratomyxa shasta is example

18 Ceratomyxa shasta J. Bartholomew Buchanan et al. (1983) reported an Oregon coastal stock of steelhead was highly susceptible to infection compared to three Columbia River tributary stocks where the parasite is endemic. Initial use of susceptible stocks of steelhead in Columbia River Basin hatcheries was probably the reason that few, if any, fish survived to return. Ibarra et al. (1992) reported crosses between susceptible and resistant stocks of rainbow trout yielded progeny with susceptibilities intermediate between the parental stocks. Currens et al. (1997) Showed introgression with susceptible, non-native, hatchery rainbow trout reduced resistance of wild trout in Metolius River of Oregon. Wikipedia

19 Release Susceptible Fish that Amplify Disease in the Wild Hatcheries pathogen-free water supplies may release fish that have not encountered certain diseases These naïve fish may acquire infections after release Such fish may provide source of infection for wild fish at times or life stages not typical of nature Ceratomyxa shasta and Parvicapsula minibicornis in the Klamath River Basin are partial examples

20 Disease transmission to naïve hatchery fish Iron Gate Hatchery Klamath Basin Tribal Water Quality Work Group A high proportion of marked hatchery salmon released into the Klamath or Trinity Rivers as disease-free smolts were found infected upon recovery downstream Origin of infections presumed to be from natural sources Significant disease with apparent loss of infected hatchery fish within river Transmission or risk to wild fish not demonstrated

21 Introduce Pollutants or Stressors to Ecosystem Effluent from large hatchery may have local effects Release of chemicals (drugs, antibiotics) High loads of nutrients (algae growth, low D.O.) Altered temperature Changes may increase stress to wild fish Most likely to occur in small watersheds

22 Lookingglass Hatchery

23 Acknowledgements Western Fisheries Research Center Gael Kurath US Fish and Wildlife Service Scott Foott Oregon State University Jerri Bartholomew University of Washington Kerry Naish Thomas Quinn Ray Hilborn Rachael Life