Status of Lake Huron Walleye

Status of Lake Huron Walleye
David G. Fielder
Michigan DNR
Arunas Liskauskas
Ontario MNR
St. Marys
River
St. Joseph
Thessalon
Channel
Mississagi
River
River
St. Ignace
Straits
Cheboygan
River
Spanish
Bay of McGregor
River
Islands
Bay
Chikanishing
River
French River & Lake Nipissing
Key River
Magnetawan River
Shawanaga River
Ocqueoc
River
Shebeshekong River
Moon River
Thunder
Bay
Severn River
Au Sable River
Nottawasaga River
Saginaw
Bay
Notable historic
walleye populations &
fisheries in Lake
Huron.
Saginaw River
System
Lower lake
Sources
Schneider and Leach 1977
Schneider and Leach 1979
Reckahn and Thurstan 1991
Commercial,
subsistence, and
recreational harvest of
walleye in Lake Huron
Nearshore Fish Community Response
To Food Web Changes
Lake Zones
Shallow Benthic
Shallow Benthic
Pelagic
Zone
Zebra mussels
Quagga mussels
Zebra mussels
Quagga mussels
Deep Benthic
Age-0 walleye trawl CPUE Saginaw Bay
And percent hatchery contribution
Trawl mean CPUE (no./10min tow)
70
0%
60
50
24%
40
8%
0% 0%
0% 0%
30
18%
20
0%
10
0
81%
81% 85% 61%85%
96%
0%
0%
1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
Year
Yearling Walleye CPUE from Saginaw Bay
Gillnet Collections
14
12
10
8
6
4
2
0
1994
1996
1998
2000
2002
2004
Survey Year
2006
2008
2010
2012
50
0.45
45
0.4
40
0.35
35
0.3
30
0.25
25
0.2
20
0.15
15
10
0.1
5
0.05
0
0
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Walleye abundance
Alewife abundance
Angler CPUE
Angler CPUE (walleye/hr)
Abundance (gillnet CPUE)
Saginaw Bay Walleye Open Water Angler Catch Rate and
Abundance of walleye from the gillnet survey 1994 - 2013
Walleye Age-3 Mean Length at Capture (mid Sept.)
530
Mean Length (mm)
510
490
470
450
430
Target level (Aug-Sep)
Recovery Zone (Aug-Sep)
410
390
State ave. (Aug-Sep)
370
350
1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013
Year
Numbers of age-2+ walleyes in Saginaw Bay 1986-2011
5,000,000
Numbers of Walleye
4,500,000
4,000,000
3,500,000
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
1986
1989
1992
1995
1998
Year
2001
2004
2007
2010
4%
4%
6%
14%
17%
16%
50%
58%
21%
1.5%
12000
Lake trout
Walleye
Chinook salmon
8000
120
4000
60
0
0
Prey (kt)
16000
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
Predator (ton)
Predator and Prey Biomass
240
180
500000
450000
Walleye Harvest
by Fishery in Lake
Huron 1986-2011
Walleye Harvested
400000
350000
300000
250000
200000
150000
100000
50000
0
Year
Observed rec catch
OBS gillnet
Obs trapnet
pred by-kill
Proportion of
Fishing mortality
by age
Proportion of fishing mortality
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2
3
4
5
6
7
8
9
Age
Fmrc
Fotn
Fgln
Fbkl
10
11
12
13
0.25
Trends in fishing
mortality using age5 as an indicator
Age-5 F
0.20
0.15
0.10
0.05
0.00
1986
1989
1992
1995
1998
2001
2004
2007
2010
Year
Fmrc
Fotn
Fgln
Fbkl
6,000,000
Trends in biomass
(total and SSB)
Biomass (kgs)
5,000,000
4,000,000
3,000,000
2,000,000
1,000,000
0
1986
1989
1992
1995
SSB
Total biomass
1998
Year
2001
2004
2007
2010
Commercial Fisheries
Southern Main Basin
Harvest

Largest targeted Walleye Fishery In
Ontario waters

Mixed stock fishery

Both gill-net and trap-net fishery

Stable harvest and CPUE in recent
years
CPUE

Cohort modeling indicates declining trend in biomass

Recent increases in total mortality
(Gill-net 53%; trap-net 40%)
Harvest dominated by younger age classes (2-5 yr olds)
Estimated Walleye Biomass- Cohort analysis
250
200
150
100
50
Year
3
4
5
6
7
8
9
10
11
12+
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
0
1997
Exploitable Biomass (metric tons)

Georgian Bay Walleye
Moon River

Walleye supported historically important
recreational fishery

Long-term decline in abundance

Water flow and habitat issues

Recent spawning survey CPUE lowest on record

Artificial spawning reef constructed in 2008

Evidence of successful reproduction since 2009

Overall walleye relative abundance still low
Georgian Bay Walleye
Severn Sound

Largest warm-water recreational fishery in
Georgian Bay

Historically Walleye prominent in fishery

Exploitation and habitat issues

Severe decline in relative abundance since 2010

Evidence of poor recent year classes
Georgian Bay Walleye
French River

Historically important Walleye recreational
fishery

Presumed most stable Walleye fishery due to
remoteness

Intermittent monitoring since mid 1990s
indicates progressive decline in abundance

Broad size range with evidence of ongoing
successful reproduction
rule
Walleye recruitment
S/R based on
density &
alewives
Alewife
abundance
& trend
no. wild recruits
S/R based on
stocking & wild
recruitment
Natural reproduction / stocking
Decision: stock or
not, what threshold
& what rate
Ontario gillnet
harvest
Reduction via fishing mortality
Tribal gillnet
harvest
sel, q, effort
sel, q, effort
Recreational
harvest
sel, q, effort
sel, q, effort
Consumption
Walleye population (ages 2+)
Ontario trapnet
harvest
Commercial
by-kill
9,000,000
What it looks like:
8,000,000
Total number age-2+
7,000,000
6,000,000
5,000,000
4,000,000
3,000,000
2,000,000
1,000,000
0
1986
1991
1996
2001
2006
2011
2016
2021
2026
2031
2036
2041
2046
2051
2056
2061
1986
1991
1996
2001
2006
2011
2016
2021
2026
2031
2036
2041
2046
2051
2056
2061
2036
2041
2046
2051
2056
2061
4,500,000
4,000,000
Total number age-2+
3,500,000
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
400000
350000
Harvest
300000
250000
200000
150000
100000
50000
0
1986
1991
1996
2001
2006
mrc harv
2011
2016
otn harv
2021
2026
Year
glnt harv
2031
glno harv
bkl harv
8,000,000
7,000,000
Total number age-2+
6,000,000
5,000,000
4,000,000
3,000,000
2,000,000
1,000,000
0
1986
1991
1996
2001
2006
2011
2016
2021
2026
2031
2036
2041
2046
2051
2056
2061
1986
1991
1996
2001
2006
2011
2016
2021
2026
2031
2036
2041
2046
2051
2056
2061
4,500,000
4,000,000
Total number age-2+
3,500,000
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
Looking ahead
• We believe that the continued absence
of alewives is essential for continuing
recruitment
• In the absence of alewives, density
dependent factors (in Saginaw Bay) and
perhaps other influences are now
regulating recruitment
• Sequestered productivity in the nearshore zone may be driving down
abundance perhaps by interfering with
recruitment processes
• Walleye are among top predators
shaping the Lake Huron community
today
• Demand & exploitation catching up?
70
Saginaw Bay walleye age-0 CPUE
• Recruitment is become more variable
Saginaw Bay Wild Walleye Age-0 abundance as a Function of Trends in Lake
Huron Main Basin Alewife Abundance
60
3rd order polynomial equation (cubic)
50
y = 6E-08x3 + 8E-05x2 - 0.114x + 28.33
R² = 0.437
40
30
20
10
0
0.00
100.00
200.00
300.00
400.00
-10
Main basin alewife CPUE
500.00
600.00
700.00
Saying Farewell
The harder you work, the
harder it is to surrender
that work
-Vince Lombardi
Jim Johnson
• Serving since professionally since 1972 (Nebraska/Utah)
• Alpena Station Manager (MDNR) since 1989
• In excess of 50 career publication credits
• Over 20 devoted to advancing lake trout rehabilitation
• Served as the Lake Huron Technical Committee Chair
• Led many State of Lake Huron presentations and
publications
Congratulations Jim & Dave! Enjoy your well
deserved retirements. You will be missed.