Post on 02-Jan-2016
description
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Status of Lake Trout(Salvelinus namaycush)
in Georgian Bay and North Channel
Lloyd C. Mohr
Upper Great Lakes Management Unit,
Lake Huron Office, OMNR
Owen Sound, ON
Background
Statistical Districts in Cdn Waters
Data Sources: - Commercial Harvest - Commercial Catch Sampling - Index Assessment Surveys - Recreational Surveys
LakeTrout Rehabilitation
1996 Rehab Plan
7 Active Rehab Zones
2 Proposed Sanctuaries
LakeTrout Rehabilitation
Objectives
Spawning Populations 2005
Natural Reproduction 2010
Self-Reproducing in Former Range 2020Annual sustained yield 1.12 million kg
LakeTrout Sources
• Iroquois Bay• Parry Sound
Remnant Stocks
Lake Trout Sources
11 sites• Average 850K G.Bay• 110K N. Channel• 1991 30% Backcross G. Bay• 1996 Pure Lake Trout
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
1979 1982 1985 1988 1991 1994 1997Year
Nu
mb
er S
tock
ed x
10
6 North ChannelGeorgian BayLake Huron
Stocking
Lake Trout SourcesMovement (CWT)
GB09 97.6GB08 2.4
GB10 56.5GB11 14.5GB08 14.2GB09 9.5
GB03 40.4LH03 20.1LH04 27.4GB10 8.8
%
LakeTrout Exploitation - Commercial
0
500
1000
1500
2000
2500
3000
3500
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Ha
rve
st
(kg
x 1
00
0)
U.S. HURON GEO BAY N.CHAN
Prior to 1922, Canadian Harvest combined for all 3 Basins
Annual Harvest
0
20
40
60
80
100
120
140
160
180
200
1970 1974 1978 1982 1986 1990 1994 1998 Year
Har
vest
(kg
x 1
000)
0
500
1000
1500
2000
2500
Fis
h S
tock
ed (
# x1
000)
N.CHAN
GEO BAY
HURON
Number Stocked
LakeTrout Exploitation - CommercialAnnual Harvest
0
20,000
40,000
60,000
80,000
100,000
120,000
1979 1983 1987 1991 1995 1999
Year
Ha
rve
st
(kg
)
NC3
NC2
NC1
GB4
GB3
GB2
GB1
LakeTrout Exploitation - CommercialStatistical Districts
LakeTrout Exploitation - CommercialIncidental Catch
0
20
40
60
80
100
120
140
160
180
Georgian Bay North Channel Main Basin
Nu
mb
er F
ish
/ F
ish
ing
Eve
nt 1975-1979
1980-1990
1991-1999
LakeTrout Exploitation - Commercial
95.7 92.1 87.8
2.9 <0.1 3.6
0.7 6.5 6.6
0.7 1.3 2.1
GB NC MBIncidental Catch (%)
0.0
0.4
0.8
1.2
1.6
2.0
1 2 3 4 5 6 7 8 9 10 11 12Month
kg
Lt
/ k
g L
wf1990 1991 1992 1993
1994 1995 1996 1997
LakeTrout Exploitation - CommercialIncidental Catch (Seasonal)
LakeTrout Exploitation - CommercialIncidental Catch (Spatial)
> 1,000 kg
250 - 1000
100 - 250
10 - 100
< 10
1979 1989
1999
LakeTrout Exploitation - CommercialIncidental Catch (Spatial)
1999
> 1,000 kg
250 - 1000
100 - 250
10 - 100
< 10
0
0.1
0.2
0.3
0.4
0.5
0.6
4.25 4.5 4.75 5 5.25 5.5Mesh size (in.)
Lak
e tr
ou
t /
Lak
e W
hit
efis
h 1992
1993
1994
1995
1996
1997
1998
1999
LakeTrout Exploitation - CommercialIncidental Catch (mesh size)
LakeTrout Exploitation - SportSW Georgian Bay
0
5000
10000
15000
20000
25000
30000
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
Year
Bio
mas
s (k
g) Georgian Bay
Main Basin
LakeTrout Biological Data
LakeTrout - (Mean Size)Mean Size of Lake Trout Harvested
Georgian Bay
0
500
1000
1500
2000
2500
3000
1989 1991 1993 1995 1997 1999Year
RW
T (
g)
0
100
200
300
400
500
600
FL
EN
(m
m)
RWT
FLEN
Mean Size of Lake Trout HarvestedNorth Channel
0
500
1000
1500
2000
2500
3000
1989 1991 1993 1995 1997 1999Year
RW
T (
g)
0
100
200
300
400
500
600
700
FL
EN
(m
m)
RWT
FLEN
0
1
2
3
4
5
6
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Year
Ag
e (y
r)
GB
NC
LakeTrout - (Mean Age)Known Age Fish only
0.0
0.1
0.2
0.3
0.4
0.5
1 2 3 4 5 6 7 8 9 10
1989
1999
0.00.1
0.20.3
0.40.5
0.60.7
1 2 3 4 5 6 7 8 9 10 11 12 13
1989
1999Georgian Bay
North Channel
LakeTrout - (Age Distributions)
0
100
200
300
400
500
600
700
800
1988 1990 1992 1994 1996 1998 2000
Year
Ave
rag
e F
LE
N (
mm
)
10
9
8
7
6
5
4
3
2
1
LakeTrout - (Size at Age)Known Age Fish only
North Channel Lake Trout Maturity (Female) 1998-1999
y=exp(-13.80725+(2.628768)*x)/(1+exp(-13.80725+(2.628768)*x))
AGE
M
AT
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
North Channel50% - 5.3yr
Georgian Bay50% - 4.6 yr
Georgian Bay Lake Trout Maturity (Female) 1998-1999
y=exp(-11.21678+(2.455271)*x)/(1+exp(-11.21678+(2.455271)*x))
AGE
M
AT
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
LakeTrout - (Maturity Schedule)Females
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
3 4 5 6 7 8 9Age
Pro
po
rtio
n M
atu
re
1991
1992
1993
1994
1995
1996
1997
1998
SW Georgian Bay (females)
LakeTrout - (Maturity Schedule)
0
20
40
60
80
100
1992 1994 1996 1998 2000Year
To
tal A
nn
ual
Mo
rtal
ity
(A)
LakeTrout - (Mortality)
SW Georgian Bay (Age 4+)
LakeTrout - (Sea Lamprey Wounds)
0
10
20
30
40
50
1984 1986 1988 1990 1992 1994 1996 1998
Year
# W
ou
nd
s /
10
0 F
ish
NC
GB
MB
All Data Sources
LakeTrout RehabilitationObjectives
Spawning Populations 2005
Self-Reproducing in Former Range 2020Annual sustained yield 1.12 million kg
Natural Reproduction 2010
Evaluation
• Lake Trout Survival highly variable
• Spawning Stock Size• Egg Deposition• Natural Reproduction• Age Structure• Range• Abundance• Yield
under investigation
unknown
present 2-4 locations
constricted
expansion in P. Sound
CPUE variable
???
LakeTrout Rehabilitation
LakeTrout Management
Exploitation Review •Commercial Quota and Recreational Limits
• Incidental Catch Rates
• Reporting / Assessment Issues
LakeTrout Management
Lake Trout Rehabilitation Plan Review •summarize/evaluate data
• model results
• LTRP Benchmarks
• re-evaluate assessment protocol/requirements
• where are we?
LakeTrout Management