Population Status & Ecology of Lake Sturgeon in Lake Michigan

Tributaries

Carl R. Ruetz IIIAnnis Water Resources Institute

Grand Valley State Universityruetzc@gvsu.edu

Acknowledgements• Collaborators: Matt Altenritter, Kregg Smith

(DNRE), Alex Wieten & Elizabeth Binoniemi-Smith (Gun Lake Tribe)

• Travis Ellens, Billy Keiper, & Jessica Comben• Kurt Thompson for assistance with ArcGIS• Brendan Earl (URS Corp.)• John Gulvas & Leo Torvinen (Consumers

Energy)• Funding: Consumers Energy, Michigan

Department of Natural Resources & Environment, U.S. Fish & Wildlife Service

The Lake Sturgeon (Acipenser fulvescens)

• Native to North America• Historical distribution

– Great Lakes– Hudson Bay– Mississippi River– St. Lawrence River

• Current range– 1% of historic

Life History

• Delayed maturity– Males: 14-16 years– Females: 24-27 years

• Frequency of spawning– Males: 1-2 years– Females: 3-7 years

• Spawn in rivers• Sex specific timing

Threats & Causes of Decline

• Overharvest– By-catch in commercial fishing– Caviar

• Habitat degradation– Logging

• Barriers– Construction of dams

Overall Goals

• Determine population status of lake sturgeon in Lake Michigan tributaries–Muskegon, Grand, & Kalamazoo

rivers• Examine juvenile ecology

Adult Sampling (Spring)

• Gill netting: Muskegon Lake

• Boat electrofishing: Muskegon River

Gill Netting Boat electrofishing

Year CatchEffort(hrs) Catch

Effort(hrs)

2008 1 458 7 242009 13 488 18 312010 8 984 10 14

Adult Sampling (Spring)Muskegon Lake

Larval Drift SamplingMuskegon River

• Downstream of spawning site

• 4 D-frame drift nets• Nets fished at night• Larval lake

sturgeon measured & released

Muskegon River: 2009

Date

4/18/09 5/2/09 5/16/09 5/30/09 6/13/09 6/27/09

Wat

er T

empe

ratu

re

0

2

4

6

8

10

12

14

16

18

20

22

Num

ber o

f Lak

e St

urge

on C

aptu

red

and

Obs

erve

d

0

2

4

6

8

10

12

14

16

18

20

22

Water TemperatureCapturedObserved No Larvae CapturedSturgeon Larvae Captured

Larval Drift: Muskegon RiverYear Catch Effort (hours)2008 0 2632009 32 1942010 16 525

Grand River

Juvenile SamplingMuskegon Lake

• August-November• 23 juveniles captured (2008-2010)

–14 received transmitters–10 extensively tracked + 3 current

• 5 cohorts (Ages 0, 1, 2, 4, 7)*

Distribution in Muskegon Lake

Distance from River Mouth (km)

0-0.5

0.5-1.

01.0

-1.5

1.5-2.

02.0

-2.5

2.5-3.

03.0

-3.5

3.5-4.

04.0

-4.5

4.5-5.

05.0

-5.5

5.5-6.

06.0

-6.5

Freq

uenc

y

02468

1012141618202224262830

Before TurnoverAfter Turnover

Before Turnover

During Turnover

After Turnover

Before vs. After Turnover

BT AT

Wat

er D

epth

(m)

0

5

10

15

20

25t= 7.27df= 4

p= 0.001

Monthly Movement Rate

August September October November

Mov

emen

t Rat

e (k

m/d

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6 F3,22= 1.26p= 0.312

Grand River Sampling Locations

Juvenile Movements

Grand_dt4_tracks.shpGrand_river_utm16.shpGrand_sidescan_utm16.shp

N

Grand River Habitat Mapping

Conclusions• Muskegon Lake = important nursery area

– Multiple cohorts– Residency– Suitable overwintering areas?

• Adults (<100 annually) successfully reproduce in Muskegon River– Larvae & Age-0 lake sturgeon