Gill health in marine populations of wild and cultured salmonids in British Columbia. Simon Jones Pacific Biological Station Nanaimo, BC

Transcription

1 Gill health in marine populations of wild and cultured salmonids in British Columbia Simon Jones Pacific Biological Station Nanaimo, BC Gill Health in Cultured Salmon: Current Knowledge and Future Directions Campbell River, BC. February 9-10, 2017

2 Overview of presentation Salmon aquaculture in BC Oceanographic characteristics of coastal BC Advent of AGD in BC and increased awareness of gill health Description of new collaborative gill health research project Future directions

3 Salmon aquaculture in British Columbia Atlantic salmon is BC s largest agriculture product 9 fish health management zones 92,926 tonnes jobs CAD 470 million value 1 Scrutinized by NGOs, public, government Potential for interactions with wild salmon Other impacts to coastal ecosystems data

4 Environmental determinants of gill health Pathogen Host Environment Gill integrity reflects optimal water quality Temperature Salinity Dissolved oxygen Toxins Suspended solids Microbial infection Husbandry Density Handling Feeding 4

5 FVCOM model domains in coastal British Columbia Estuarine/wind 1 Uniform seasonal salinity Tidal 2 Low summer salinity Tidal Low summer salinity Precipitation High summer salinity 1, Atmosphere-Ocean 44: (2006); 2, Atmosphere-Ocean 50: (2012)

6 Pine Island Annual salinity signal observed at lighthouses (n = 80 years) Entrance Island Amphitrite Point mean ± standard deviation Peter Chandler, IOS (DFO)

7 Loma salmonae in cultured chinook salmon: seasonal temperature effects 7

8 Unusual warm conditions in late summer

9 Warm waters moved inshore in fall and winter

10 Warm conditions in 2015; early sign of El Niño El Niño

11 Warm conditions persist in 2015; strong El Niño El Niño

12 A year goes by

13 Sea surface water temperatures among coastal zones in British Columbia

14 Infection with Paramoeba perurans and amoebic gill disease in Atlantic salmon in BC P. perurans detected in one fish; subsequent testing at site revealed additional positive samples. Elevated mortality at two other sites associated with gill pathology and positive PCR results. First report of P. perurans and amoebic gill disease in Canada. PCR evidence of infection in two additional management zones; Clinical AGD was reported in one additional zone. In the original affected zone, total daily mortality at sites with farm diagnoses of AGD increased from 0.10% to 0.29% between 2014 and In the second zone in 2015, total daily mortality at the farm with an AGD diagnosis was 0.21%. 14

15 Amoebic gill disease B. Nowak 15

16 Amoebic gill disease scoring Clear Very light Light Moderate Advanced Heavy Dr. Hamish Rodger, Vet-Aqua International

17 Amoebic gill disease scoring 17

18 Satellite* imaging of plankton blooms: Vancouver Island, *Moderate Resolution Imaging Spectroradiometer; Jim Gower, IOS (DFO) 18

19 BC fish-killing HAB species Raphidophytes Heterosigma akashiwo Chattonella cf. marina Dictyochophytes Dictyocha speculum Dictyocha fibula Pseudochattonella verruculosa Pseudopedinella pyriformis Diatoms Chaetoceros concavicornis Chaetoceros convolutus Dinoflagellates Cochlodinium fulvescens Alexandrium catenella Haptophytes Chrysochromulina spp.

20 Pseudochattonella verruculosa WCVI, September 2013 Extensive gill damage Pseudochattonella cells

21 Year Quarter Algae LDO (1) - 2 CHY(1) +(1) 3 HET(1)CHA(1) +(3) 4 - +(1) (3) 3 HET(2)CHA(3) +(4) 4 +(1) CHY(1) +(2) 3 DIC(1)+(2) +(4) 4 CHA(1) +(3) HAB and low DO events 21

22 Scyphozoa (aka jellyfish) 22

23 Increasing awareness of gill health Occurrence of AGD and ongoing HAB raised the profile of gill health in the BC industry Recognition of need for more systematic monitoring Since 2014/15, gill-scoring systems established at farm level by industry, DFO Need for standardization of methods and score criteria 23

24 Proliferative gill disease scoring Score 1 Score 2 Score 3 Score 4 Score 5 Score 1: very slight thickening OR very few lamellae affected Score 2: frequent thickening, but tips only Score 3: almost all lamellae have thickened tips and some have thickenings progressing to ~50% of the length of the lamellae Score 4: most lamellae have thickenings progressing to more than 50% of the length of the lamellae Score 5: almost all lamellae are thickened along the entire length. 24

25 DFO health audit: gill data Histopathology Random quarterly checks of active Atlantic salmon Fish on site >30 days; 3 or more pens 30 farms sampled per quarter In each of the seven coastal fish health zones, the number of farms selected is determined by the proportion of the total number of active farm Designed to allow farm-level diagnoses based on history, mortality, clinical presentation & individual testing Gill scoring from both L & R; n = 10; 2015; Q2; individual farm scores 25

26 New gill health research project in BC Marine reservoirs of infectious agents associated with proliferative gill disorders in farmed salmon Two-year collaboration: DFO, industry, BC-MOA Year 1 3 sites x 4 monthly samples (farmed, wild salmon, non-salmonids) Year 2 Environmental data (DO, Temp, Sal, HAB) Gill histology Molecular assessment P. perurans, D. lepeophtherii, Ichthyobodo spp., SGPV* Increased number of sites, increased sampling frequency *culture gill homogenates on cells 26

27 Looking forward Adopt a standardised gill health scoring system for use industry-wide and by regulators Integrate scoring system with histopathology and diagnostic datasets Validate scoring system as a useful indicator of significant change in health status Coordinated industry-wide collection and analysis of environmental data (e.g., low DO, HAB, Scyphozoa, etc.) Role of changes in gill health as indicators (or predictors) of subsequent changes in disease status Improved understanding of interactions among sequential events: low DO, algal blooms, gill infections, gill lesions, secondary lesions and systemic effects 27

28 Acknowledgements DFO Ian Keith, Sonja Saksida, Peter Chandler, Jim Gower BC MOA Gary Marty, Heindrich Snyman Microthalassia Consultants Nicky Haigh Marine Harvest Canada Diane Morrison, Brad Boyce, Mykolas Kamaitis Cermaq Canada Barry Milligan, Kaitlin Fitzpatrick Grieg Seafoods Tim Hewison, Patrick Whittaker 28