Barrie Creeks, Lovers Creek, and Hewitt's Creek Subwatershed Plan

The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatershed Plan
5.2.1 Overview of aquatic communities – Tributaries
5.2.1.1
Fish Community
Studying the health of the fish community of the Barrie Creeks, Lovers Creek and Hewitt’s
Creek subwatersheds provides an important window into the health of the aquatic system as a
whole. Fish are sensitive to a great number of stresses including water quality, temperature,
flow regimes, and the removal of in-stream habitat. While they are able to move quickly in
response to a sudden change in conditions (e.g. a release of a chemical into the system) and
are therefore not a good indicator of these types of issues, prolonged stresses will eventually
cause a shift in the fish community from one that is sensitive and requires clean, cool water to
survive to one that is more tolerant of lower quality conditions. Long term monitoring will identify
changes and trends occurring in the fish community the subwatershed, and will help to identify
and guide restoration works.
A total of 33, 32 and 21 species, respectively, have been captured from the Barrie Creeks,
Lovers Creek and Hewitt’s Creek subwatersheds since 1975 (Table 5-1). Some of these
species have only historic records (before 1990), some only current (after 1990) and others
have both (1975-present). The fish communities in the subwatersheds range from cold
headwater communities featuring such species as brook trout (Salvelinus fontinalis) and mottled
sculpin (Cottus bairdii) to diverse warm large order systems containing such species as
largemouth bass (Micropterus salmoides) and brown bullhead (Ameiurus nebulosus).
The water temperature of a system can dictate the composition of the fish community, as well
as determine the way systems are managed. Figure 5-1 below illustrates the combination of
maximum air temperatures versus water temperature at 4pm (when water temperatures tend to
reach their maximum) that makes a cold, cool or warm water stream. Typically, the average
maximum summer water temperatures for a cold water system is 14°C. Cool water is
approximately 18°C and warm water systems have an average summer maximum daily water
temperature of approximately 23°C (Stoneman and Jones, 1996). This temperature rating
system has been used to classify the tributaries in the Lake Simcoe watershed.
Figure 5-1: Cold, cool and warm water trout stream temperature ranges (Stoneman and Jones,
1996).
Chapter 5: Aquatic Natural Heritage 208