By Betty Rebellato
Anglers and nature lovers alike get satisfaction from seeing
healthy populations of fish in our lakes and streams. Whistler’s waterways
support populations of kokanee, rainbow trout, bull trout, sculpins, threespine
stickleback, and, more recently in Alta Lake, cutthroat trout. But do the same
fish exist in the Whistler area as were here historically?
For some species, the answer is likely no. The increasingly
rare bull trout is indigenous to the Whistler area, as are sculpin and, likely,
stickleback. Rainbow trout and kokanee likely exist here solely as a result of
stocking. Both rainbow trout and kokanee have been stocked in Whistler-area
lakes since the early 1920s as part of a nationwide (and continent-wide) effort
to enhance angling opportunities. Remnants of these populations have become
naturalized in the area and reproduce in the wild, continuing their existence
in the Whistler Valley.
So how might the introduction of rainbow trout and kokanee have
affected the local ecology of the area? Little historic information is
available to determine what existed here prior to the intervention of man.
However, many of the Lower Mainland and B.C. coastal lakes that have been left
unaltered support populations of wild coastal cutthroat trout, which leads one
to assume they would also have existed in Whistler-area lakes. Coastal
cutthroat trout hybridize easily with rainbow trout, and the introduction of
rainbow trout over the years has likely caused the disappearance of cutthroat trout
from our waters.
Unlike most strains of rainbow trout, which feed primarily on
insects and plankton, cutthroat trout are piscivorous (fish eating) and would
have subsisted on stickleback in the area. If cutthroat trout truly did exist
historically in the area, then their disappearance from our lakes would have
allowed the stickleback population to grow to unnatural proportions, allowing
them to expand into more niches and consume more plankton (their main food
source) than before. In an effort to reduce the stickleback population back to
what is believed to be more natural levels, the Province of B.C. in conjunction
with the Whistler Angling Club introduced sterile cutthroat trout into Alta
Lake on a trial basis beginning in 2003.
In addition to affecting the stickleback population, fish
stocking practices may have also caused a decline in amphibian populations in
the Whistler area. Research has shown that the presence of rainbow trout and
other trout species causes a decrease in both the number and size of many
species of amphibians, especially in those water bodies with little habitat
complexity in which amphibians can hide. The practice of stocking fish into a
lake can affect amphibian populations both through predation of palatable
species, such as long-toed salamanders, northwestern salamanders, and pacific
chorus frogs, and through the introduction of disease to other species of
amphibians, such as the western toad.
Long-time local resident and fish historian Eric Crowe has been
researching the origins and changes to British Columbia’s fish populations
since the start of major fish stocking practices in the early 1870s. The
Whistler Naturalists invite you to join us on Thursday, Jan. 18 at 7:30 p.m. at
Millennium Place to hear Eric’s take on how stocking has affected cutthroat
trout, steelhead, and other populations of fish in Whistler.
Eric Crowe––The Fish Detective. Thursday, Jan. 18,
7:30 p.m. at Millennium Place: After years of detective work, Eric has sleuthed
some surprising conclusions about the history of fish in our local lakes and
rivers. Come find out what secrets he’s uncovered. Admission by donation. Call
604-932-8900 for more details.
Monthly bird walk. Saturday, Feb. 3, 8 a.m. at the base of Lorimer Road. For details, call Michael Thompson at 604-932-5010.