1

Fish EcologyLake and Stream Leaders Institute

July 31, 2015Dr. Willie Fetzer, MSU

wfetzer@msu.edu

2

From a terrestrial standpoint, what are the unique challenges and opportunities associated

with life in water?

www.thelensflare.com/profile.php/jimlegg

3

From a terrestrial standpoint, what are the unique challenges and opportunities associated

with life in water?

Challenges:• Viscosity• Low oxygen (lakes)• Low light levels• Rapid H20 movement

(streams)

Opportunities:• Floating• Vertical movement

(lakes)• Downstream

transport (streams)

4

Consider your favorite Michigan aquatic animal.

Does it live in all lakes and streams in Michigan?

Why or why not?

www.thelensflare.com/profile.php/jimlegg

5

Lake Zonation Littoral

Pelagic

Profundal

6

Stream Order

Stre

am f

low

7

Overview of lake and stream fishes:

sizehabitat

feeding habitsreproductive characteristics

8

Fish: Benthivores, Planktivores, and Piscivores

Bluegill?Sculpin

Northern Pike

www.rudybenner.com/

Alewife

9

Fish: Benthivores, Planktivores, and Piscivores

Bluegill?Sculpin

Northern Pike

www.rudybenner.com/

Alewife

10

Most fish species share the same general life cycle.

Eggs

LarvaeAdults

Juveniles

11

But….the details are highly variable among species.

Eggs

LarvaeAdults

Juveniles

Spawningstrategies:• nesting• demersal• pelagic

• Hatch size varies (~3-15 mm TL)• Small hatch –

starvation • Large hatch -

predation

•Age at maturity varies widely among species.

And even within species!!

• Bluegill• Three reproductive strategies of males

• Bulls, sneakers, and female mimics (cuckholders)

12

13

How many fish species are in a lake or stream?

Fish species number typically increases with lake size.

Bachmann et al. 1996CJFAS 53:842-85565 Florida lakes

14

How much fish biomass is in a lake?

Ney 1996 TAFS

15

Iowa

No. of Fish Spp in Lake

0 4 8 12 16 20 24 28

No.

of L

akes

0

10

20

30

40

50 WI netting

No. of Fish Spp in Lake

0 4 8 12 16 20 24 28 32

No.

of L

akes

0

10

20

30

40

50

Michigan

No. of Fish Spp in Lake

0 4 8 12 16 20 24 28 32

No.

of L

akes

0

10

20

30

40

50 WI shocking

No. of Fish Spp in Lake

0 4 8 12 16 20 24 28 32 36

No.

of L

akes

0

10

20

30

40

50

Number of Fish Species per Lake

Median: 10 spp

Med: 12 spp

Median: 13 spp

Median: 15 spp

16

Total No. of SPP and 5 most prevalent fish speciesIowaN<46BG-96%LMB-96%Ch. Cat-91%BL. CP-89%Wh. CP-61%

MichiganN<88YP-89%PS-88%LMB-82%BG-79%NP-76%

WI nettingN<107BG-98%LMB-89%YP-86%PS-78%RB-65%

WI shockingN<114BG-94%LMB-87%YP-83%PS-75%BL.CP-74%

17

What are typical fish community types?

Shallow lakes, no connections

Shallow lakes, with connections

Stratified lakes, with deep water oxygen

Stratified lakes, with oxygen depletion

Fishless lakes

18

Fish Communities: shallow lake, no connection

• Typically < 2.5m mean depth• Water column isothermal…no cold water• Prone to low oxygen under winter ice

Clear state: Turbid state:

19

Fish Communities: shallow lake, no connection

• Who predominates? - plantivores and benthivores that tolerate low oxygen but have relatively few anti-predation adaptations

Umbridae(e.g., mudminnow)

rivers.snre.umich.edu/ www311/aqfish.html

20

Fish Communities: shallow lake, WITH connection

• Winterkill less likely: littoral piscivores, littoral planktivores, benthivores and detritivores predominate.

Esocids

Northern pike

muskellunge

Centrarchids

Largemouth bass

pumpkinseed

Cyprinidscarp

21

Fish Communities:Stratified lakes WITH deepwater oxygen

• Inshore littoral areas tend to be warm and oxygenated, with relatively high benthic production and rooted vegetation.

• Surface pelagic waters (epilimnion) tend to be warm, light, and oxygenated.

• Deep waters tend to be cooler and darker, but with year-round oxygen (>4 mg/l; 4o C).

22

Fish Communities:Stratified lakes WITH deepwater oxygen

Percids(coolwater)

Walleye(piscivore, low light)

Yellow Perch(planktivore, piscivore)

Coregonids

Ciscoalso herrings(planktivores)

Salmonids(coldwater)

Lake trout(piscivore)

Rainbow troutSculpin(benthivore)

Cottids

23

Fish Communities:Stratified lakes WITHOUT deepwater oxygen

• Inshore littoral areas tend to be warm and oxygenated, with high production. May be turbid or may have rooted vegetation.

• Surface pelagic waters (epilimnion) tend to be warm and oxygenated…but with high nutrients, production, and relatively low water clarity.

• Deep waters tend to be cooler and darker. High algal biomass decomposes on the bottom, leads to oxygen depletion in the summer.

24

Percids(coolwater)

Fish Communities:Stratified lakes WITHOUT deepwater oxygen

Walleye(piscivore, low light)

Yellow Perch(planktivore, piscivore)

Salmonids(coldwater)

Lake trout(piscivore)

Rainbow trout

Clupeids

Gizzard Shadalso Threadfin Shad

omnivores

Class 1: High temp., small surface area, intermediate depth

Warmwater centrarchidsYellow bullheadGrass pickerelSpotted garLake chubsucker

25

Fish Communities:Michigan Lakes

Wehrly et al. 2012

Class 2: High temp., large surface area, deep

BowfinCarpChannel catfishBrook silverside

Class 3: Low temp., large surface area, deep

Coolwater centrachidsPercidsColdwater species

26

Fish Communities:Michigan Lakes

Wehrly et al. 2012

Class 4: Moderate temp., small surface area, intermediate depth

Warmwater centrarchidsCoolwater species

Yellow perchWhite sucker

27

Fish Communities:Michigan Lakes

Wehrly et al. 2012

Class 5: Moderate temp., intermediate surface area, intermediate depth

Brown bullheadBluntnose minnowLow oxygen tolerant

Class 6: Low temp., intermediate surface area, intermediate depth

White suckerPercidsNorthern Pike

28

Fish Communities:Michigan Lakes

Wehrly et al. 2012

Ultimate drivers:

TemperatureSizeDepth

Proximate drivers:

ProductivityOxygenHabitat diversity

Thermal structureLake zones

29

Fish Communities:Michigan Lakes

Wehrly et al. 2012

30

Humans: The Top Predator

31

Foodwebs: a trophic pyramid

http

://r

idge

.icu.

ac.jp

/gen

-ed/

ecos

yste

m-j

pgs/

food

-web

.jpg

How does fishing affect lakes?

• Predators– Reduced abundance– Reduced size

• Prey fish– Increased abundance

• Introduction of non-native species– Baitbucket introductions– Livewells– Stocking

32

Can fishing affect water clarity?

33

Trophic Cascades

• A cascade of interactions among members of a food web that lead lakes to exhibit alternative characteristics

34

35

LMB only

LMB removed

Other consequences of fishing

• Trophic triangles

36

Lots of adult predators

Adults maintain heavypredation pressure on prey, controlling their abundance

Successful reproduction is common

Trophic triangles (pristine state)

37

Trophic triangles (disturbed)

Fishing removes adults

Prey becomes abundant

Abundant prey outcompete or feed on juvenile predators

Predators are unable to successfully reproduce

38

What are other ways humans can affect fish?

• Many ways– Already discussed nutrients, fishing

• I will discuss two– Residential development– Invasive (non-native species)

39

Lakeshore development

• Houses, condos, resorts, etc

• Riparian alteration– Removal of trees– Lawns

• Lakeshore manipulation– Seawalls– Beaches– Removal of woody and

macrophyte habitat

40

Key concept• What happens on land affects what

happens in water– Aquatic-terrestrial coupling

• How does this happen?– Fish directly consume terrestrial

items• Insects• Mammals

– Terrestrially-derived habitat• Coarse woody habitat (CWH)

– Terrestrially-derived nutrients• Influences primary productivity

41

Habitat alteration• Removal of CWH

– CWH abundance strongly affected by residential development

Marburg et al. 2006

42

Removal of macrophytes• Development

affects floating-leaf plants the most

• Other growth forms not affected as much.

Radomski and Goeman 199643

How does this affect fish?

• Benthic invert diversity reduced– Abundance too

Brauns et al. 2007 44

Reduced fish growth

• Significant reductions in fish growth with higher development

• Low development: most of shore undeveloped

• High development: nearly 100% of shore developed

Schindler et al. 2000

45

Introduced Species

• AKA: Exotic, Nuisance, Invasive, Non-native, nonindigenous

• Estimated cost of introduced species– $137,000,000,000 per year (2000)

• >130 fish species introduced into the US

Common carp

Round goby

Silver carp

46

Introduced Species:Global homogenization

Afghanistan   Israel  Spain Albania  Italy  Sri Lanka Argentina  Japan  Sudan Australia  Jordan  Swaziland Austria  Kazakhstan  Sweden Azores Is.  Kenya  Switzerland Belgium  Kerguelen Is.  Taiwan Bolivia  Korea Rep  Tanzania Brazil  Kyrgyzstan  Turkey Bulgaria  Latvia  UK Chile  Lesotho  Ukraine China Main  Liechtenstein  Uzbekistan Colombia  Lithuania  Venezuela Costa Rica  Luxembourg  Zimbabwe Cyprus  Madagascar  Alaska Czech Rep  Madeira Is.  Armenia Denmark  Malawi  Canada Dominican Rp  Morocco  Mexico Ecuador  Nepal  Russian Fed Eritrea  Netherlands  Slovenia Estonia  New Zealand  USA Ethiopia  Norway  Iceland Finland  Pakistan  Indonesia France  Panama  Iraq Germany  Papua N Guin  Lebanon Greece  Peru  Malaysia Guyana  Poland  Mauritius Hawaii  Portugal  Syria Honduras  Reunion  Tahiti Hungary  Romania  Thailand India  SerbiaMontenegro  Tunisia Iran  Slovakia  Uruguay Ireland  South Africa  Zambia 

Rainbow trout

47

Introduced Species:Global homogenization

• Largemouth bass • Smallmouth bass

48

Introduced species in the Great Lakes

49

Introduced species

• 63 fish species– Established: 33– Reported, failed: 16– Reported, status uncertain: 14

• 2 decapods– Rusty crayfish, Red swamp crayfish

(Procambarus clarkii)

50

Vectors of introduction

• From outside NA:– Shipping– Aquarium/bait trade

• From inside NA:– Canals– Bait trade– Stocking

51

ShippingRound goby Eurasian ruffe

European flounderChinese mitten crab

Require saltwater to complete life cycle 52

Canals• Morone spp.

– Yellow bass, white perch

• Alosa spp.– Blueback and

skipjack herring, alewife

53

Stocking• Pacific salmonids

– 4 successful– 2 or 3 failed

• Others: brown trout, common carp

Masou salmon (O. masou): failed Cutthroat trout (O. clarkii): failed

Chinook salmon (O. tschawytscha)

54

Indirect effects of invasive species

55

Summary• Aquatic food webs are the net result

of numerous factors– Within-lake– Landscape

• Humans can disrupt (or help) aquatic food webs– Conservation of natural shorelines– Reduction in harvest of top predators– Reduce introductions of non-native

species56

Questions?

57