BIODIVERSITY RESEARCH: Oncorhynchus mykiss

[Spiel]

BIODIVERSITY RESEARCH

www3.interscience.wiley.com

 

The contribution of newly established populations to the dynamics of range expansion in a one-dimensional fluvial-estuarine system: rainbow trout (Oncorhynchus mykiss) in Eastern Quebec

Isabel Thibault*, Louis Bernatchez and Julian J. Dodson

 

Département de Biologie, Québec-Océan, 1045 Avenue de la Médecine, Université Laval, Québec, QC, Canada, G1V 0A6

 

Correspondence to *Isabel Thibault, Département de Biologie, Québec-Océan, 1045 Avenue de la Médecine, Université Laval, Québec, QC, Canada, G1V 0A6.

E-mail: [email protected]

Copyright Journal compilation © 2009 Blackwell Publishing

 

KEYWORDS

 

Biological invasions • fluvial estuarine system • naturalized populations • population assignment • rainbow trout • stepping-stone dispersion model

 

ABSTRACT

 

Aim Rainbow trout (Oncorhynchus mykiss, Walbaum 1792) is an exotic salmonid invading eastern Canada. First introduced for recreational fishing in Ontario, Quebec and the Maritime provinces, the species is now spreading in salmon rivers located in Eastern Quebec, where its stocking is strictly forbidden. Newly established populations have been found along the St Lawrence Estuary. To effectively mitigate the potential threat the invasion poses to native salmonids, we aimed to document the invasion's origin and progress in the St Lawrence River and estuary. We first determined genetic origins among several potential wild and cultured source populations, found at the upstream and downstream extremities of the St Lawrence system. Thereafter, we studied the range expansion, predicting that the invasion process conforms to a one-dimensional stepping-stone dispersion model.

 

Location

 

Recently invaded salmon rivers that flow into the Estuary and Gulf of St Lawrence in Quebec, and watercourses supporting naturalized populations (Lake Ontario, Lake Memphremagog and Prince-Edward-Island rivers).

 

Methods

 

Rainbow trout from 10 potential source populations (wild and domestic strains) and 243 specimens captured in salmon rivers were genotyped at 10 microsatellite loci. Genetic origins of specimens and relationship between colonies were assessed using assignment analyses based on individuals and clusters.

 

Results

 

Invasion of rainbow trout in Eastern Quebec is directed downstream, driven by migrants from upstream naturalized populations, found in the Ganaraska River (Lake Ontario), and, to a lesser extent, in Lake Memphremagog. Populations from the Maritime provinces and domestic strains do not contribute to the colonisation process. A recently established population in Charlevoix (Eastern Quebec) supplies other downstream colonies.

 

Main conclusions

 

Rainbow trout is spreading from Lake Ontario downstream to Eastern Quebec using the St Lawrence River system as an invasion corridor. Range expansion in a downstream direction is driven by a more complex stepping-stone dispersion model than predicted. Management options to protect native salmonids include reducing the effective size of the Charlevoix population, impeding reproduction in recently colonized rivers, halting the upstream migration of anadromous spawners, and curtailing stocking events inside the stocking area.

[Roy]

One man's garbage is another man's gold I guess.

[asdve23rveavwa]

One man's garbage is another man's gold I guess.

 

Well said...I thought the same thing reading this yesterday...hard to consider a Rainbow an "invasive species." However when it comes to messing up an ages old fishery such as the Atlantic salmon in eastern ontario I guess it truly is. That said...I will gladly take any they don't want!!!!!!!!!!!!!!!!!!!!!!!!!!

[solopaddler]

Not sure what the fuss is about, they spawn at different times of the year.

In addition here in Ontario they seem to be co-habitating quite nicely in the Soo rapids.

Wild populations of each specie have been running the river up there for quite some time now.

 

Interesting nontheless especially the fact that it's ganaraska strain rainbows that are infiltrating the salmon rivers.

They're a very hardy robust strain of fish. My guess is eradicating them might prove difficult.