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