Lake Ontario Atlantic salmon

Rationale

Theory suggests that to restore an extirpated population (a local population that no longer exists but other source populations of the species still exist in other areas), a source population that is genetically similar (ancestry match) has a higher success at restoration. However, another approach for the selection of a source population is to match the local environments between the extirpated and source populations (environment match). Environment matching may be particularly important when the environment of the extirpated population has changed substantially from the historical environment.

Lake Ontario Atlantic salmon (Salmo salar), a population extirpated by 1900, presents an ideal system to examine the performance of source populations that differ in the degree of ancestry matching and environment matching to important components of the altered environment. Important environment changes to Lake Ontario that are impediments to Atlantic salmon restoration include competition with non-native salmonids and a current diet of high thiaminase-containing prey fishes. Here, I will compare the performance of three populations of Atlantic salmon in experiments examining the effects of competition and thiaminase.

Experiments

  1. Early-life history stages
  2. Semi-natural streams
  3. Natural streams
  4. Thiamine deficiency

For more information on Lake Ontario Atlantic salmon see:
COSEWIC Assessment and Status Report 2006
COSEWIC Assessment and Status Report 2010

For more information on the Restoration Program and volunteering see:
Bring back the salmon

Atlantic salmon
Atlantic salmon (Salmo salar)

Source population selection

Restoration efforts can draw on several source populations using the following criteria:

  • ancestry matching: The selection of a source population is done to match the genetic similarity between the source and extirpated populations. The rationale for this approach is that populations that are close genetic relatives to an extirpated population should possess the same genes important to fitness in the environment of the extirpated population. This is the classical perspective for source population selection.
  • environment matching: The selection of a source population is done to match the local environments between the source and extirpated populations (Moritz 1999; Houde et al. 2015). Source populations inhabiting environments similar to the extirpated population environment should possess genes that are important to fitness in the environment of the extirpated population. This is an emerging perspective for source population selection.

Environment matching may be particularly effective when the environment of the extirpated population has changed substantially from the historical environment. Conceivably in such cases, environment matching (to the new conditions) will be more important than ancestry matching. Little, however, is known about the relative importance of ancestry versus environment matching in population restoration.

The source Atlantic salmon populations for reintroduction to Lake Ontario are:

  1. Lac Saint-Jean, Québec, Canada
  2. Sebago Lake, Maine, USA
  3. LaHave River, Nova Scotia, Canada

Table 1: Summary of the Atlantic salmon source populations

Lake Ontario Lac Saint-Jean Sebago Lake LaHave River
genetic similarity  
 
Migration
potamodromous ✓ (mostly)
anadromous capacity capacity
 
Competition
rainbow and brown trout
coho and chinook salmon
 
Thiamine deficiency
rainbow smelt
alewife

Note: Competition and thiamine deficiency have been identified as impediments to the restoration of Atlantic salmon into Lake Ontario. Sebago Lake information is for fish stocked into Lake Champlain, Vermont.

For more information on the choice of source populations see:
Evaluation of selected strains of Atlantic salmon as potential candidates for the restoration of Lake Ontario

Publications

Houde ALS, Garner SR, Neff BD. 2015. Restoring species through reintroductions: strategies for source population selection. Restoration Ecology 23: 746-753. |PDF|

References

Moritz C. 1999. Conservation units and translocations: strategies for conserving evolutionary processes. Hereditas 130: 217-228. doi: 10.1111/j.1601-5223.1999.00217.x.

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Last updated July 2017
© Aimee Lee Houde