Science Response 2016/005

Habitat, Passage and Stocking Considerations for Gaspereau at Sandy Lake, Nova Scotia

Context

The Indian River (44.6918°N, 63.9103°W) drains into St. Margaret’s Bay, Halifax County.  For much of the past century, all areas upstream to the outflow of Sandy Lake have been inaccessible to diadromous fish species; originally due to a mill dam that was subsequently converted for hydro-electric power generation in the 1920s.  In 2015, the current operator, Nova Scotia Power Incorporated, is constructing a fishway to allow for fish passage into Sandy Lake and connected tributaries.  This fishway is expected to provide upstream passage into Sandy Lake for several diadromous species, primarily Alewife (Alosa pseudoharengus), but potentially Blueback Herring (Alsoa aestivalis), American Eel (Anguilla rostrata), Atlantic Salmon (Salmo salar) and sea-run Brook Trout (Salvelinus fontinalis).

It has been proposed that Alewife and/or Blueback Herring (collectively called Gaspereau hereafter) could be stocked into Sandy Lake upon completion of the fishway in order to expedite population establishment in the river system.  Although it has not been scientifically documented that Alewife or Blueback Herring were native to Indian River prior to the construction of the dam at Sandy Lake, the range of both these diadromous fishes includes Nova Scotia and it is likely that they were found historically in the Indian River.  Currently, the river is expected to have adequate water quality to support Gaspereau.  This response provides scientific advice with respect to the following objectives:

1. Estimate the area of potential fish habitat that will be made available to Gaspereau by providing fish passage at the Sandy Lake dam, with further consideration in the estimate of assuming fish passage at Big Indian Lake dam;
2. Estimate of the abundance of Gaspereau this area could theoretically support;
3. Evaluate potential population growth of Gaspereau from an initial small population size, including any estimated time frame(s) for expected growth;
4. Identify factors that should be considered in stocking the system with Gaspereau (e.g. species sensitivity, sources of fish, etc.), including the identification of alternate sources of information; and
5. Identify other factors that should be considered with respect to fish passage and a potential Gaspereau stocking program (e.g. passage efficiency), including assumptions, limitations, and sources of uncertainty.

This response will make use of the available scientific literature as well as previously peer-reviewed methodologies.  In general, much more information exists on the dynamics of Alewife populations relative to those of Blueback Herring, so the information in this document pertains predominantly to Alewife.

This Science Response Report results from the Science Response Process of October 15, 2015, on the Considerations for Fish Habitat, Passage, and Gaspereau Stocking at Sandy Lake, Nova Scotia.

Complete document (PDF, 265 KB)

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