Évaluation des risques de la nasse de Nouvelle

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ISSN 1499-3848 (Printed / Imprimé)
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© Her Majesty the Queen in Right of Canada, 2011
© Sa Majesté la Reine du Chef du Canada, 2011
Research Document 2010/108
Document de recherche 2010/108
Risk assessment for New Zealand mud
snail (Potamopyrgus antipodarum) in
Canada
Évaluation des risques de la nasse de
Nouvelle-Zélande (Potamopyrgus
antipodarum) au Canada
Thomas W. Therriault1, Andrea M. Weise2, Graham E. Gillespie1 and Todd J. Morris3
Fisheries & Oceans Canada
1Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7
2Institut Maurice-Lamontagne, 850 route de la Mer, Mont-Joli, QC G5H 3Z4
3Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, ON L7R 4A6 ON
Pêches et Océans Canada
1Station biologique du Pacifique, 3190 Hammond Bay Road, Nanaimo, C.-B. V9T 6N7
2Institut Maurice-Lamontagne, 850 route de la Mer, Mont-Joli, QC G5H 3Z4
3Centre canadien des eaux intérieures, 867 Lakeshore Road, Burlington, ON L7R 4A6 ON

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TABLE OF CONTENTS / TABLE DES MATIÈRES
ABSTRACT................................................................................................................................... v
RÉSUMÉ...................................................................................................................................... vi
INTRODUCTION ..........................................................................................................................1
INTRODUCTION ..........................................................................................................................1
RISK ASSESSMENT ................................................................................................................1
ÉVALUATION DES RISQUES..................................................................................................1
SCOPE AND SCALE ................................................................................................................3
PORTÉE ET ÉCHELLE ............................................................................................................3
BIOLOGY..................................................................................................................................5
BIOLOGIE.................................................................................................................................5
VECTORS.................................................................................................................................8
VECTEURS...............................................................................................................................8
DISTRIBUTION.......................................................................................................................10
AIRES DE RÉPARTITION ......................................................................................................10
METHODS AND MATERIALS ....................................................................................................27
MÉTHODES ET MATÉRIAUX ....................................................................................................27
RISK ASSESSMENT METHODOLOGY.................................................................................27
MÉTHODOLOGIE D’ÉVALUATION DES RISQUES ..............................................................27
RESULTS ...................................................................................................................................43
RÉSULTATS...............................................................................................................................43
POTENTIAL DISTRIBUTION IN CANADA .............................................................................43
RÉPARTITION POTENTIELLE AU CANADA.........................................................................43
SURVEY RESULTS................................................................................................................48
RÉSULTATS DU SONDAGE..................................................................................................48
RISK ASSESSMENT FOR THE NEW ZEALAND MUD SNAIL ..............................................58
ÉVALUATION DES RISQUES POUR LA NASSE DE NOUVELLE-ZÉLANDE ......................58
CONCLUSIONS..........................................................................................................................68
CONCLUSIONS..........................................................................................................................69
RECOMMENDATIONS...............................................................................................................72
RECOMMANDATIONS...............................................................................................................72
ACKNOWLEDGEMENTS ...........................................................................................................74
REMERCIEMENTS.....................................................................................................................74
REFERENCES ...........................................................................................................................74
APPENDIX A: .............................................................................................................................84
ANNEXE A :................................................................................................................................84

v
Correct citation for this publication:
La présente publication doit être citée comme suit :
Therriault, T.W., Weise, A.M., Gillespie, G.E. and T.J. Morris. 2011. Risk assessment for New
Zealand mud snail (Potamopyrgus antipodarum) in Canada. DFO Can. Sci. Advis. Sec.
Res. Doc. 2010/108. vi + 93 p.
Therriault, T.W., Weise, A.M., Gillespie, G.E. et T.J. Morris. 2011. Évaluation des risques de la
nasse de Nouvelle-Zélande (Potamopyrgus antipodarum) au Canada. Secr. can. de
consult. sci. du MPO. Doc. de rech. 2010/108. vi + 93 p.
ABSTRACT
Non-indigenous species continue to be dispersed to new environments. The New Zealand mud
snail (Potamopyrgus antipodarum) was identified in the Great Lakes in 1991 and, more recently,
identified on the west coast of Canada in 2006. This snail possesses many traits making it well
suited for invasions including a high reproductive rate and a broad range of environmental
tolerances. Its life-history characteristics enhance long-distance natural dispersal while further
dispersal via a number of human-mediated vectors is probable. In some systems, this small
snail reaches extremely high densities and can alter ecosystem services and trophic
relationships by grazing primary producers, outcompeting native invertebrates, and negatively
influencing higher trophic levels. Based on impacts of New Zealand mud snail elsewhere, and
owing to their extensive invasion history in Europe and the western United States, there is
considerable concern about the potential ecological impacts if New Zealand mud snail spreads
in Canada, especially to inland freshwater or other coastal ecosystems. Fisheries and Oceans
Canada conducted a national risk assessment, including a peer-review workshop during March
2010, to determine the potential risk posed by this non-indigenous gastropod to Canadian
coastal and inland waters. This assessment evaluated the probability of arrival, survival,
reproduction, and spread and associated potential consequences (impacts) to determine risk.
These components were assessed using an expert survey and an expert workshop using the
best available information on the biology, potential vectors of introduction, and impacts in both
native and introduced ranges. This assessment also incorporated measures of environmental
suitability from an ecological niche model and bedrock geology to identify locations with calcium
deposits required for shell building. The risk assessment, based on a widespread invasion,
concluded that the New Zealand mud snail generally posed low risks to most Canadian aquatic
ecosystems with a moderate risk posed to freshwater biodiversity in most Canadian freshwater
drainages. However, at smaller spatial scales the risk posed by this species could be much
higher. Further, considerable uncertainty identified for some stages of the invasion cycle
highlights the need for additional research, especially about potential impacts of this gastropod
in Canadian ecosystems, as this information is critical for potential management.