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Lake Michigan 2011 Status and Trends of Prey Fish Populations Chuck Madenjian , Bo Bunnell , Tim Desorcie , Margi Chriscinske , Melissa Kostich , and Jean Adams USGS Great Lakes Science Center Ann Arbor, MI. Historical backdrop. sea lamprey control; salmonine stocking. Round goby - PowerPoint PPT Presentation
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Lake Michigan 2011Status and Trends of Prey Fish Populations
Chuck Madenjian, Bo Bunnell, Tim Desorcie, Margi Chriscinske,Melissa Kostich, and Jean Adams
USGS Great Lakes Science CenterAnn Arbor, MI
Lake
Mic
higa
nSp
ring
TP (u
g/L)
0
2
4
6
Lake
Mic
higa
nSa
lmon
ine
biom
ass
(kt)
05
101520253035 Historical backdrop
1960s 1970s 1980s 1990s 2000s
sea lamprey control;salmonine stocking
Great Lakes WaterQuality Agreement
Madenjian et al. 2002; Bunnell et al. 2006; US-EPA
dreissenidinvasion
Round gobyinvasionBythotrephes
invasion
1 9 7 3 1 9 8 1 1 9 8 9 1 9 9 7 2 0 0 50
1 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
7 0 0
Nu
me
ric
de
ns
ity
(n
um
be
r/h
a)
1 9 7 3 1 9 8 1 1 9 8 9 1 9 9 7 2 0 0 5
Ye a r
0
1 0
2 0
3 0
Bio
ma
ss
de
ns
ity
(k
g/h
a)
Ad u l t a l ewi fe
1975 1980 1985 1990 1995 2000 2005 20100
10000
20000
30000
40000
Year
Bio
mas
s (g
/ha)
Lake Huron
Concern that salmonine consumption is exceeding alewife production
Alewife energy density has declined (need to eat 22% more alewife to maintain constant growth)- Madenjian et al. 2006.
Chinook salmon have increased their reliance on alewife as a prey (maybe not the case for lake trout?).
Year1994-1996 2009-2010
Proportion
0.0
0.2
0.4
0.6
0.8
1.0AlewifeBloaterSmeltRound gobyDiporeia
Lake Michigan Chinook salmon diet… further alewife domination
<500 mm
Jacobs et al. in review
Lake Michigan Chinook salmon diet
Year1994-1996 2009-2010
Proportion
0.0
0.2
0.4
0.6
0.8
1.0AlewifeBloaterSmeltStickleback
… further alewife domination
>500 mm
Jacobs et al. in review
Concern that salmonine consumption is exceeding alewife production
Alewife energy density has declined (need to eat x% more alewife to maintain constant growth)- Madenjian et al. 200x.
Chinook salmon have increased their reliance on alewife as a prey (maybe not the case for lake trout?).
Alewife age-class distribution is more truncated (similar to Lake Huron pre-2003). 2011: up to 80% age-1.
1 5 3 5 5 5 7 5 9 5 11 5 1 3 5 1 5 5 1 7 5 1 9 5 2 1 5
Total length (mm)
0
5
1 0
1 5
2 0
2 5
Perc
ent
Age 3
Age 0
Age 5Age 6
Age 8
Age 2Age 1
Age 4
Age 7
2006
1 5 3 5 5 5 7 5 9 5 11 5 1 3 5 1 5 5 1 7 5 1 9 5 2 1 5
Total length (mm)
0
5
1 0
1 5
2 0
2 5
Perc
ent
Ag e 3
Age 0
Ag e 5Ag e 6
Ag e 2Ag e 1
Ag e 4
Ale wi fe le n g th -ag e d is trib u tio n , 2 0 0 9
15 35 55 75 95 115 135 155 175 195 215
Total length (mm)
0
5
10
15
20
25
30
35
40
Perc
ent
Ag e-0Ag e-1Ag e-2Ag e-3Ag e-4Ag e-5Ag e-6
Age 0Age 1Age 2Age 3Age 4Age 5Age 6
Ale wife le ngth-age dis tribution, 2 0 1 0
15 35 55 75 95 115 135 155 175 195 215
Total length (mm)
0
5
10
15
20
25
30
35
40
Perc
ent
Ag e-0Ag e-1Ag e-2Ag e-3Ag e-4Ag e-5Ag e-6
Age 0Age 1Age 2Age 3Age 4Age 5Age 6
Ale wife le ngth-age dis tribution, 2 0 1 1
1 9 7 3 1 9 8 1 1 9 8 9 1 9 9 7 2 0 0 50
5 0 0
1 0 0 0
1 5 0 0
2 0 0 0
2 5 0 0
Nu
me
ric
de
ns
ity
(n
um
be
r/h
a)
1 9 7 3 1 9 8 1 1 9 8 9 1 9 9 7 2 0 0 5
Ye a r
0
3 0
6 0
9 0
Bio
ma
ss
de
ns
ity
(k
g/h
a)
Ad u l t b loa te r
1 9 7 3 1 9 8 1 1 9 8 9 1 9 9 7 2 0 0 50
1 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
Nu
me
ric
de
ns
ity
(n
um
be
r/h
a)
1 9 7 3 1 9 8 1 1 9 8 9 1 9 9 7 2 0 0 5
Ye a r
0
1
2
3
4
5
6
7
Bio
ma
ss
de
ns
ity
(k
g/h
a)
Ad u l t ra in b o w s me l t
Deepwater s culpin1.86 kt
Slimy s culpin1.93 kt
Bloater3.70 k t
Rainbow s melt0.47 kt
Ninespine s tick leback0.04 k t
Alewife7.64 k t
Round goby1.83 k t
Lake Michigan, 2011
1 9 7 3 1 9 8 0 1 9 8 7 1 9 9 4 2 0 0 1 2 0 0 8
Year
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
5 0 0
Lake
-wid
e bi
omas
s (k
t) Bloater
Sl imy sculpin
Deepwater sculpinRainbow smel t
Ro u n d g o b y
Ni nespine sti ckleback
Alewi fe
Conclusions and prognosis• Total prey fish biomass, as estimated by the bottom
trawl, in 2011 was 17.47 kt, the lowest value in the time series
• Total prey fish biomass has remained below 30 kt since 2007
• Two factors contributing to low prey fish biomass:
prolonged period of low bloater recruitment and intensified predation by Chinook salmon on alewives
• Adult alewife biomass density has remained low for an eight-year period and age distribution has been truncated during the past three years; characteristics similar to Lake Huron alewife population prior to collapse during 2003-2004
Conclusions and prognosis (continued)
• Whether or not alewife population collapses in Lake Michigan depends on several factors: Chinook salmon abundance, alewife year-class strength in 2012, environmental effects on alewife survival
• To quantify bottom-up effects, additional years of surveillance and additional analyses needed
• Prey fish biomass in 2011 was far below FCO
• Whether prey fish biomass will ever exceed 100 kt in the near future will depend on the ability of the bloater population to recover