5.Biodiversity Issues in the Thompson-Okanagan
British Columbia is the most biologically diverse province or
territory in Canada. British Columbia is home to 143 mammal species, 454 birds,
20 amphibians, 19 reptiles and 450 species of fish. There are approximately
2,850 vascular plants, 1,600 lichens, 522 species of attached algae, and over
10,000 fungi species. It is believed that number of insect species range from
50,000 to 70,000. Some of these species are not found anywhere else in Canada.
Of all species native to the country, 9 % of the birds, 12 % of the reptiles,
17 % of the mammals, 27 % of the amphibians and 25 % of the freshwater fish are
exclusive to British Columbia. The biodiversity of British Columbia is not only
significant to Canada, but it is also significant on a global scale. British
Columbia is home to a significant portion of global populations of mountain
goats, blue grouse, trumpeter swans and grizzly bears.
The diversity of British Columbia varies across the province. The
Okanagan Valley is a part of the Southern Interior Ecoprovince
. In this region, low levels of precipitation, hot summers and mild
winters provide a habitat for species that are unique both to British Columbia
and Canada. For example, of the 20 species of bats found in Canada, fifteen are
present in the south Okanagan and two are exclusive to this area. Like the rest
of the world, however, the diversity of this area is threatened by human
population growth and the following specific problems:
Growing populations have threatened and endangered many
species and habitats in the Okanagan. Only 9 % of the natural grasslands native
to the Okanagan remain, due to roads, malls, orchards and housing developments
expanding into undisturbed land.
Fire suppression is changing the biodiversity of the Okanagan.
Many of the low elevation areas are believed to be fire-induced ecosystems. In
other words, in a natural setting, periodic fires maintain the proper species
composition. With controlled fires, higher plants, such as trees, succeed the
native vegetation and cause their competitive exclusion.
The introduction of new species threatens many species in the
Valley. Over the past few decades several species have been introduced, mainly
accidentally, which are causing havoc for native species. Eurasian
Milfoil , Purple Loosestrife and Knapweed
are three foreign species that have become well established in the
area during last 30 years. In Okanagan Lake, the introduction of Mysis
shrimp by the Ministry of the Environment may be partially
responsible for population declines of Kokanee . Exotic
species that are relatively new to the area include Leafy Spurge
, Rush Skeleton Weed , Yellow Starthistle
, Dalmatian Toadflax and Sulphur Cinquefoil
. The provincial government is attempting to control these species and
prevent their establishment like Eurasian Milfoil and Knapweed.
Livestock grazing has also had a major impact on the
biodiversity in the Okanagan. Overgrazing can disturb the soil and natural
vegetation and allow perfect conditions for the invasion of like
Knapweed . Livestock can also affect the water supply in
temporary pools that supports a variety of small species.
Recreation and Traveling. There are a high number of wildlife
killed each year on Okanagan roads reducing populations. It is estimated that
3,000 deer are hit and killed each year in the Valley. Off-road vehicles
disturb sensitive wildlife and soils and allow for the invasion of weeds.
Although sport hunting is controlled with licenses and regulations, there is
still a problem with poaching in the area. Deer, moose, elk and bear are
several species that are illegally killed in the Okanagan for sale on the black
Reduction in the Kokanee Fishery
Kokanee (species - Oncorhynchus nerka ) are a unique form
of sockeye salmon that were landlocked following the last ice age. In North
America, natural populations occur in Alaska, Yukon Territory, British
Columbia, Washington, Idaho, and Oregon. In the past, Kokanee have been a
traditional food for native Indians of these regions. More recently, Kokanee
have become a popular sport fish.
Kokanee typically complete their life cycle, which varies from
three to five years, in the lakes and tributaries in which they were born.
Mature adult Kokanee spawn either in streams and rivers or near the shores of
lakes during the late summer to early fall.
Okanagan Lake Kohanee
Kokanee populations is some Thompson-Okanagan lakes have
undergone dramatic losses in numbers. One such lake showing a decline in
kokanee nimbers is Okanagan Lake. Declining numbers are most often noted in the
number of Kokanee that spawn each year. In the 1970s, estimates suggest that
about one million Kokanee spawned in Okanagan creeks each year. By 1994, this
number declined 10 % of this value.
There are a number of factors responsible for the decline in
Okanagan Lake Kokanee numbers. Many of these factors destroy Kokanee spawning
habitat. Scientists believe that of all Okanagan spawning habitat that existed
100 years ago, only 10 to 20 % remains today. Declining Kokanee populations are
thought to be due to:
Over-fishing. It has been suggested that
Okanagan Lake has been over-fished to a point where the Kokanee population has
dropped, although this is not well documented. Over-fishing has likely played a
part in the Kokanee fishery collapse, but it has probably been minimal. In
1988, biologists estimated that over 200,000 Kokanee were caught from Okanagan
Lake. Normally this number would be acceptable for a lake the size of Okanagan,
but with such limited spawning habitat, this count is considered very high. A
similar situation occurred in the west arm of Kootenay Lake during the
mid-to-late 1970s. The fishery there was many times larger than that of
Okanagan Lake. In a study of the fishery collapse, over-fishing did appear to
have a major effect, but several other factors contributed to the decline.
Logging Activities. Logging mainly affects
Kokanee populations by impacting their spawning grounds. A number of stream
characteristics, important to Kokanee, may be altered due to logging practices.
a) Logging alters stream flow hydrology. Logged areas tend to
have decreased fall and winter flows and sudden rapid spring freshets (runoff),
when compared to undisturbed areas. This means that fish eggs can dry out, be
exposed to freezing, or be flushed out prior to hatching.
b) Logging and its' associated activities, such as road
building, can cause increases in stream sediment loads. Clear-cuts can cause
increases in sediment loads due to mudslides and debris flows. Increased
sediments may ruin spawning grounds by "choking" them out with fine particulate
c) Logging practices can affect water quality, including
temperature, water chemistry and dissolved oxygen concentration. Salmonid
fishes, such as Kokanee, require pristine spawning conditions which include
cold, clean, well-oxygenated water. Lethal temperatures are often achieved in
streams that have had their riparian (streamside) vegetation removed. This has
been observed in Mission Creek, one of Okanagan Lake's major spawning channels.
Improper logging techniques may result in increased nutrient loading in streams
and decreased oxygen availability for Kokanee eggs.
Stream Modification. Many tributaries (streams)
of Okanagan Lake have undergone some form of stream modification in recent
decades. For example, the Okanagan River was diked and channeled during the
late 1950s in an effort to reduce flooding in the Penticton area. Mission Creek
in Kelowna was also channeled for a major portion of its lower reach. This
resulted in effective flood control. Stream modification destroys Kokanee
spawning habitat in several ways.
a) Channeling results in the scouring away of the spawning
substrates. Good spawning substrates, consisting of small, unconsolidated rock
and gravel, are replaced with larger rocks and boulders, which are useless to
b) Streamflow is altered so that suitable spawning areas are dry
by the time spawning takes place, or shortly afterwards, resulting in high
Kokanee egg mortalities. In other areas, stream flow is concentrated so it is
too fast for the Kokanee to efficiently spawn. During spring freshets (runoff),
boulders can crash over the spawning grounds due to increased stream velocities
in the channels.
c) Channeling results in the destruction of riparian vegetation
along modified streams. This decreases stream shading, resulting in higher
temperatures in the fall, and much lower temperatures in the winter. These
temperatures may be lethal to delicate Kokanee eggs.
Lakeshore Development. Although shore spawning
Kokanee are not well documented, lakeshore modification has likely affected
their numbers. The development of lakeshore has resulted in the destruction of
spawning beds along it. Man-made beaches and road-building alongside the lake
have probably destroyed much of the habitat for shore-spawning Kokanee.
Water Use. The Okanagan Valley relies heavily
on water for agricultural and domestic uses. Several streams have significant
amounts of water removed for these purposes. In addition, many streams travel
through residential areas where storm sewers empty into them. These uses have
negatively affected Kokanee spawning habitat.
a) It is not uncommon to see streams that contain prime spawning
habitat become reduced to a trickle by the end of the summer (when the Kokanee
spawn). The lack of water leads to higher temperatures in the fall, which are
also detrimental to Kokanee and their eggs. This situation has repeatedly
occurred at Trout Creek, Summerland, for several years.
b) Other streams are frozen during the winter months because
water flow is minimal, killing Kokanee eggs.
c) Low flows promote the settling of fine particulate matter
(sedimentation) which results in the smothering and death of Kokanee eggs.
d) Lake drawdown has not been much of a problem, but whenever it
does occur, the consequences to the entire shore-spawning population are
Introduction of Mysis relicta. Mysis
relicta, commonly referred to as opossum or mysis shrimp, was introduced
into Okanagan Lake in 1966. These organisms were introduced in hopes of
boosting the productivity of the lake, providing extra forage for game fish and
enhancing the fisheries industry. Decisions for the introduction were based on
several other North American and northern European lakes that observed
increased productivity within a few years after the introduction of Mysis
relicta. In the beginning , fish populations rose variably for the lakes,
but then began to collapse. Scientists discovered that Mysis relicta is a good
prey item for large Kokanee, but not for Kokanee aged less than one year. The
shrimps are too large for small Kokanee to handle. The major food source for
young Kokanee in Okanagan Lake is a small zoo plankton species called Daphnia,
otherwise termed the "water flea." Unfortunately, Daphnia is also the preferred
food item for Mysis relicta. This lead to competition for the same food source,
but the shrimps are more efficient predators than the Kokanee. They feed during
the night, whereas the Kokanee do not, and they have a rapid generation time.
Mysis shrimps have few predators and normally inhabit different zones of the
lake than the Kokanee. It is unknown if Mysis relicta populations have
stabilized in Okanagan Lake. If they continue to rise, the Kokanee population
will continue to drop.
Saving the Kokanee
One of the major projects in the Okanagan to help restore
Kokanee populations is the Mission Creek Spawning Channel. The channel was
developed to restore favorable conditions for Kokanee spawners. Clean gravel
and special fencing was installed to direct Kokanee into the best spawning
areas. It was hoped that these efforts would increase egg and fry survival
rates from 5 % in the wild to 80 % in the channel. To date, the channel has not
been as successful as hoped. In 1992, 36,000 Kokanee used the spawning channel,
but by 1995 this number dropped to 5,000.
In addition to costly enhancement projects such as the one at
Mission Creek, the Province of British Columbia imposed a ban on Kokanee
fishing in Okanagan Lake in 1995. Scientists believe that this ban will be in
effect to at least the year 2001. To avoid Kokanee over-fishing in nearby
lakes, the province also reduced catch limits from 5 to 2 Kokanee per day on
Wood and Kalamalka Lake.
Introduction of Knapweed
Two types of Knapweed, diffuse and spotted, are common throughout
Diffuse Knapweed ( Centaurea diffusa Lam)
Distribution. Diffuse Knapweed occurs over a
wide range of ecological habitat types. It tends to dominate in dry valley
bottoms in the Bunchgrass zone, in the transition areas of Ponderosa Pine zone
and in the interior of the Douglas Fir biogeographic zone. It therefore occurs
primarily in the Kootenays, Thompson-Nicola and Okanagan regions, the Kettle
River Valley and the Fraser Canyon. Diffuse Knapweed is also present at a lower
abundance in the Cariboo-Chilcotin. In the Okanagan, diffuse Knapweed is more
dominant in the drier regions south of Kelowna.
Description. Diffuse Knapweed has a single
upright stem 20-100 centimeters. (8-40 inches) tall and numerous spreading
branches. Plants bolt in early May, usually producing one stem with numerous
flower buds which bloom in July and August. It has white, sometimes pink or
purple, urn shaped flowers surrounded by yellowish green bracts with narrow to
short distinct, stiff spines. It is a biennial to short-lived perennial weed.
Diffuse Knapweed spreads by seed dispersed with the movement of plant material.
Under rangeland conditions, over 900 seeds per plant are formed while over
18,000 seeds may be produced under irrigation. This plant is contains volatile
oils and is extremely bitter tasting but non-poisonous.
(A compound has been isolated in Russian knapweed that is cancer
causing. This compound may also occur in spotted and diffuse knapweed. Please
be careful not to injest knapweed or have its sap enter open cuts on the skin.)
Spotted Knapweed (Centaurea maculosa Lam)
Distribution. Spotted Knapweed is found
throughout British Columbia. It is found primarily at lower to mid-elevations
of the southern interior from the Nelson area through the Kootenay, Okanagan,
Thompson-Nicola, and Cariboo- Chilcotin regions. It also occurs in isolated
pockets elsewhere in the province. In the Okanagan, spotted Knapweed
essentially grows in the moister areas of Vernon and Armstrong.
Description.Spotted Knapweed is a short-lived
perennial weed that disperses mainly by seeds. Mature plants are 20-120
centimeters (8-48 inches) tall, with long fibrous tap roots. Overwintering
rosettes bolt in early May to produce one to fifteen stems that are somewhat
hairy when young (likewise are its young leaves) and highly branched.
Thistle-like pink to purple flowers, 1-1.5 centimeters long bloom from July
through to October. Bracts of the flower head are easily recognised having a
black-tipped fringe, giving the flower head a spotted appearance. Each flower
is capable of producing 400 seeds under rangeland conditions and over 25,000
seeds when irrigated. The plant contains volatile oils with a distinctive smell
and has an extremely bitter, non-poisonous taste.
(A compound has been isolated in Russian knapweed that is cancer
causing.This compound may also occur in spotted and diffuse knapweed. Please be
careful not to injest knapweed or have its sap enter open cuts on the skin.)
Origin and Dispersal Mechanisms
Knapweed was introduced from Eurasia in the early 1900s. Since
Knapweed has no naturally indigenous enemies or parasites in North America, it
rapidly spread across the province. The Okanagan grasslands became infested
with Knapweed during the 1940s and 1950s, and it has become well established
during the last three decades.
Knapweed is easily distributed great distances by being caught
up and transported in the under carriage or doors of recreational vehicles,
trains, light air craft landing at infested airstrips, logging trucks, and
heavy machinery. It is also spread by florists, who use Knapweed in dried
floral arrangements. Hay-farmers moving from infested to non-infested sites can
transport the weed along with them. Animals and birds may pick up the weed and
disperse it. Some birds and small rodent species that eat Knapweed seed and
then disperse it in their faeces. Wind can also disperse seeds and sever
diffuse Knapweed at ground level when mature, to blow it around in a tumbleweed
Both Knapweed species are highly competitive and are capable of
invading grassland sites and out competing all native vegetation. In addition,
these sites supply domesticated animals with 80 % of their diet as grasses and
herbs. Knapweed encroachment can also destroy the forage base resulting in
significant declines in deer and elk populations.
Over 40,000 hectares (100,000 acres) in British Columbia are
infested with Knapweed, reducing forage potential by up to 90 % in some areas.
There is approximately 1 million hectares (2.7 million acres) of grassland
range and undetermined areas of fringe forest in British Columbia which
Knapweed can potentially infest. If spread to its ecological limit, Knapweed
could infest up to 8-10 million hectares (20-26 million acres) in Western
Canada. To date Knapweed has resulted in an economic loss of over $400,000
annually in equivalent hay production in British Columbia. If Knapweed spread
to its limits, that figure could climb to over $13 million annually.
.Successful long-term control requires the combination of proper
grazing management, judicious herbicide use, the development of effective
biological control and a high level of public awareness and
responsibility..Containment programs in British Columbia using herbicides are
currently underway to protect non-infested grassland. In the Okanagan, Knapweed
has been established for at least 30 years and cannot be eliminated using
chemical herbicides. Biological controls include seed reducing flies (
Urophora affinis and Urophora quadrifasciata ) from Eurasia that are now
well established throughout infested areas. These flies can reduce Knapweed
seed production by 95 %. Further reduction in seed production has resulted from
release of a moth ( Metznera paucipunctella ) against spotted Knapweed
and a root feeding beetle ( Sphenoptera jugosslavica ) against diffuse
Knapweed. In 1976, root feeding beetles were released near White Lake (just
outside of Penticton) to control diffuse Knapweed. The populations
etablished themselves and these beetles are now collected and transported to
other Knapweed infested sites in British Columbia. There are several other
insects, including other moths and beetles that can be used successfully to
control Knapweed infestations. Research shows that insects used in combination
is the best defence for controlling the spread of Knapweed.
Threatened and Endangered Species of the Thompson-Okanagan
There are numerous mammal species in the Okanagan either
classified as threatened or endangered. Some of these species cannot be found
anywhere else in British Columbia and some cannot be found anywhere else in
a) Pallid Bat (Antrozous pallidus)
b) Spotted Bat (Euderma maculatum)
c) Badgers (Taxidia taxus)
d) Nuttail's Cottontail (Sylviagus
e) Western Harvest Mouse (Reithrodontonys
f) White Tailed Jackrabbits (Lepus
Bird populations in the Okanagan region are primarily effected
by urbanization and agricultural practices. The riparian habitat, especially
that along creeks that drain into the lakes or Okanagan River is a popular
farming area and development site that affects the breeding habitat for many
birds. Birds in the Thompson Okanagan region that are presently classified as
threatened or endangered include:
a) Western Screech Owl (Otus kennicotti)
b) Lewis' Woodpeckers (Melanerpes lewis)
c) Burrowing Owl (Athene cunicularia)
d) Flammulated Owl (Otus flmmeolus)
e) Peregrine Falcons (Falco peregrinus
f) Grasshopper Sparrow (Ammodramus
g) Prairie Falcon (Falco mexicanus)
h) Sage Thrasher (Oreoscoptes montanus)
i) Yellow Breasted Chat (Icteria virens)
The Thompson Okanagan area has the highest reptilian species
density for British Columbia. Some biologists believe that the region south of
Penticton is the most likely place for the discovery of a reptile species new
to the province. Reptiles at risk in the Okanagan include:
a) Short-horned Lizard (Phrymosoma
b) Nightsnake (Hypsiglena torquata)
c) Short-Horned Lizard (Phrynosoma
d) Western Rattlesnake (Crotalus viridis)
While amphibians are generally associated with damp, aquatic
ecosystems there are some species that survive in the dry valley of the
province's southern interior. Amphibian species suited to drier climates are
known as habitat generalists (that is they have a substantial
range in which they can move to and from a water source). Amphibians at risk in
the Okanagan Valley are mainly of this type:
a) Great Basin Spadefoot Toad (Scaphiopus
b) Tiger Salamander (Ambystoma tigrinum)
The diversity of vegetation is reduced by the introduction of
species, overgrazing and development. Grasslands provide habitat for a large
number of species, many of which are now considered threatened or endangered.
It is difficult to find any natural grasslands left in the Valley. Areas that
are inaccessible to humans and livestock are the only ones that remain.
Ponderosa pine and bunchgrass are also considered threatened while riparian
areas and lakeshore forests are believed to be very threatened. In the South
Okanagan alone, 67 plant species are considered rare, threatened or endangered.
The invertebrates comprise of the largest component of British
Columbia's biodiversity, but the least amount of information is known on this
major biological group. It is virtually impossible to apply an actual status to
the species due to a lack of information. Scientists believe that in British
Columbia there are approximately 35,000 species of insects, but only about
15,000 have been discovered to date. This biological group is important in that
their diversity is a good indicator of small, unique habitats. The problem for
most of the threatened and endangered invertebrates is habitat destruction.
Within the province there are roughly fifty species of insects that are on the
endangered or threatened lists. It is important to note that invertebrates are
not considered wildlife in the province of British Columbia and are
consequently not included in the Wildlife Act's endangered species list. Some
endangered or threatened insect species in the Thompson-Okanagan include:
a) Back Swimmer (Notonecta spinosa)
b) Ground Mantis (Litaneutria manor)
c) Tiger Beetle (Cicindela parowana)
d) Vivid Dancer (Argia vivida)