Effects of Lake Fertilization on Kokanee in Kootenay Lake, B.C.
Ken Ashley, Harvey Andrusak and Dale Sebastian Min. of Water, Land and Air Protection, Prov. of B.C
2002 Northwest Fish Culture ConferenceDec 4, 2002 Bellingham, WA
Presentation Outline
• Effect of upstream impoundments andMysis introduction on Kootenay Lake•Lake fertilization experiment•Response of kokanee and GerrardRBT’s to enrichment•Conclusions
Sayward Lakes
Lower Fraser Lakes
Arrow Lake
KootenayLake
CANADABRITISH COLUMBIA
U.S.A.
PacificOcean
Mysid-kokanee history in BC
•1949 – first BC introduction to Kootenay Lake: an inappropriate model due to unique morphometry+nutrients
•1968+1974 - Upper and Lower Arrow•Mysids added to 16 more BC lakes by 1980 and throughout Western North America and Scandinavia
• Dam construction and operation– Duncan Dam - 1967 (Columbia River Treaty on
inflow Duncan River)– Libby Dam - 1973 (Columbia River Treaty on
inflow Kootenai River)• Cominco fertilizer plant operations
– Kimberly production starts - 1953– production doubles to triples - 1962 to 1965– pollution control measures - 1969 to 1979– plant closure - 1987
• Biological manipulations– Mysid shrimp introduction - 1949 + 1950
Patterns of major human disturbance: Kootenay Lake
Effect of Mysis on productivity of CDN North Temperate Lakes and Reservoirs
Kootenay Lake experience provided distorted picture Studies later indicated M. relictamajor competitor with kokaneeSevere negative impacts on kokanee populations Experiences in other lakes well documented
Kootenay Lake Food WebTrout
(Yellowfin, Gerrard, bull trout)
Kokanee
Macrozooplankton
Phytoplankton
Mysis relicta
(cannibalism)
Rotifers
Total Phosphorus Concentration (in lake)
Total Phosphorus Load
Predicted Surface Total Phosphorus Concentrations (July)
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
60 65 70 75 80 85 90 95
Year
Su
rfac
e T
ota
l Ph
osp
ho
rus
(m
g/L
)
natural Kootenai hydrograph
natural Duncan hydrograph
Baseline Surface TP
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
1,600,000
1965 1970 1975 1980 1985 1990 1995
Year
Ko
ten
ay L
ake N
ort
h A
rm
Ko
kan
ee e
scap
em
en
t
Effect on oligotrophic food webs
• Mysid introduction generally leads to delayed collapse of pelagic planktivores (kokanee), particularly in oligotrophic lakes and reservoirs• kokanee collapse was confounded/masked/delayed by multiple basin sale manipulations (nutrients, impoundment)•planktivore collapse predicted to be followed by collapse of obligate piscivores (Gerrard RBTs)• restoration of kokanee required innovative solutions•hatchery solutions were not an option
Adaptive Management
•Active adaptive management
•Definition: policies that rely on deliberate probing for information (Walters, 1986)
Adaptive Management Recovery plans: Kootenay Lake
•large scale fertilization experiment•used in-lake north-south nutrient gradient design
•Fertilizer Loading schedule:•Phase 1 (5 years): 1992-1996 – constant at 47.1 MT P• Phase 2 (5 years): 1997-2001 – variable P loading:
1997- 29.5 MT, 1998 – 22.9 MT, 1999 – 22 MT 2000 – 29 MT, 2001 – 47.1 MT, 2002 – 47.1 MT
Kootenay Lake Fertilizer P loading
-10
0
10
20
30
40
50
60
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Met
ric
ton
nes
of
P
Kootenay kokanee abundance (Maximum Likelihood Estimates) from fall acoustic surveys, 1985-99.
0
10
20
30
40
85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01
Year
Mil
lio
ns
of
ko
ka
ne
e
Kootenay L. kokanee - abundance by age group (stacked)
0
5
10
15
20
25
30
35
40
85 86 88 89 90 91 92 93 94 95 96 97 98 99 00 01
Fall survey year
Millio
ns o
f ko
kan
ee
Age 1-3
Age 0
Combined
Kootenay L kokanee - North vs South Arm
02
46
810
1214
1618
20
85 86 88 89 90 91 92 93 94 95 96 97 98 99 00 01
Fall survey year
Millio
ns o
f ko
kan
ee
South Arm
North Arm
Meadow Creek Kokanee
0.0
200.0
400.0
600.0
800.0
1000.0
1200.0
1400.0
1600.0
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Esca
pem
ent (
x 1,
000)
Meadow Creek Kokanee
0
5
10
15
20
25
30
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Fem
ale
mea
n le
ngth
(cm
)
Meadow Creek Kokanee
0
50
100
150
200
250
300
350
400
450
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Fecu
ndity
0
5
10
15
20
25
30
1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000
Year
Leng
th (c
m)
100
150
200
250
300
350
400
450
Fecu
ndity
Females
Males
Fecundity
Adaptive Management
Mean length (cm) of Meadow Creek kokanee spawners and fecundity
Meadow Creek Kokanee
y = 30.269x - 408.35
R2 = 0.8983
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25 30
Female Mean length (cm)
Fecu
ndity
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 10
50
100
150
200
250
300
350
400
450
Meadow Creek and Lardeau kokanee escapement and fecundity
Meadow Creek Kokanee
0
10
20
30
40
50
60
70
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Egg
Dep
ositi
on (m
illio
n)
Meadow Creek Kokanee
0
5
10
15
20
25
30
35
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Tota
l fry
pro
duci
on (m
illio
n)
0
5
10
15
20
25
30
35
85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01
Meadow Creek fry measured production estimates compared to totalin-lake fry hydroacoustic estimates
0
50
100
150
200
250
300
85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 0 1Fry Year
Leng
th (m
m)
8586
8788
8990
9192
9394
9596
9798
9901
Year class
Kokanee length-at-age over time (1985-2001). Data from trawl caught fish for ages 0+ to 2+ with lengths standardized to account for different capture dates between years. Age 3+ lengths are mean lengths of spawners from Meadow Creek.
0
100
200
300
400
500
600
700
57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 1
Year
Peak
cou
ntAnnual escapement of Gerrard rainbow trout measured by the highest single day count (Total count is x 2.3)
Comparison of number of kokanee all ages and numbers of large fish assumed to be predators from acoustic monitoring
Kootenay Lake kokanee and Gerrards
-
5,000,000
10,000,000
15,000,000
20,000,000
25,000,000
30,000,000
35,000,000
40,000,000
45,000,000
50,000,000
92 93 94 95 96 97 98 99 00 01
Year
No
of k
okan
ee
-
100,000
200,000
300,000
400,000
500,000
Num
ber
of la
rge
pred
ator
s
No. of kokanee (all ages)
No. of fish >32 cm length (predators)
Figure 11. Trends in prey to predator ratios in Kootenay Lake during the fertilization period based on acoustic monitoring. Note: 700 kokanee/rainbow is considered minimum levels to maintain prey populations in Idaho
Kootenay Lake - predator prey ratios
0
1000
2000
3000
4000
5000
6000
7000
92 93 94 95 96 97 98 99 00 01
Y e a r
Number of Kokanee/Predator
suggested maintenance level (Melo)
0 5 10 15 20 km
Hydroacoustic Surveys
Transects 1 - 20
Trawl Survey
Trawl Locations T(1 - 6)
T1 Shelter BayT2 Halfway RiverT3 Nakusp
T4 EdgewoodT5 Bowman CreekT6 Cayuse Creek
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British Columbia
Study area reach breaks
Hill Cr. and Spawning Channel
Kootenay R.
Castelgar
1716
15
14
13
12
11
18
19
20
21
10
9
8
7
6
5
4
3
21
Columbia R.
Nakusp
T3
TE
T2
T1
T4
T6
Huge Keenleyside
Dam
Edgewood
Beaton Arm
Upper Arrow
Narrows
Renata
Burton
RevelstokeDam
Revelstoke
T5
Revelstoke Reach
Lower Arrow
TE Below Narrows (extra)
(Reach 1)
(Reach 3)
(Reach 4)
(Reach 6)
(Reach 5)
(Reach 2)
Lower Arrow
0
2
4
6
8
10
88 89 90 91 92 93 94 95 96 97 98 99 00 01
Survey year
Num
bers
of k
okan
ee
(mill
ions
)
Arrow Reservoir
0
5
10
15
20
25
88 89 90 91 92 93 94 95 96 97 98 99 00 01
Survey year
Num
bers
of k
okan
ee
(mill
ions
)
Upper Arrow
0
3
6
9
12
15
88 89 90 91 92 93 94 95 96 97 98 99 00 01
Survey year
Num
bers
of k
okan
ee
(mill
ions
)
Upper and Lower Arrow Reservoir kokanee escapement
0
200000
400000
600000
800000
1000000
1986 1988 1990 1992 1994 1996 1998 2000 2002
Year
To
tal
esca
pem
ent
Closing comments
• Lake enrichment has been successful to date in restoring kokanee in Kootenay Lake and Arrow Reservoir
• these ecosystems are large, but fragile -kokanee are the canary in the coal mine
• restoration can be expensive, and uncertain• Active adaptive management approach is a
key part of BC’s lake/reservoir kokanee recovery plans
• remember Aldo Leopold: “The first rule of intelligent tinkering is to keep all of the parts”.
0200,000400,000600,000800,000
1,000,0001,200,0001,400,0001,600,000
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Ko
ote
na
y L
ak
e N
ort
h A
rm
Ko
ka
ne
e e
sc
ap
me
nt