Examining Freshwater and Marine Habitat Use by Juvenile Blueback Herring (Alosa aestivalis)

Through Otolith Microchemical Methods

Molly Payne WynneDr. Karen Wilson

University of Southern MaineDepartments of Biological Sciences and Environmental Science

Acknowledgements

Maine Sea Grant

Maine EPSCoR Sustainability Solutions Initiative

Alewife Stock Structure in the Gulf of Maine Project (NFWF Grant)

Dr. T. Willis and the Wilson/Willis Lab Members

The Alewife harvesters of Maine and Maine Department of Marine Resources

River Herring Landings (NMFS)

Freshwater

Spring Fall

Ocean adults

eggs young of year

Juveniles

spawning adults

Approach: Otoliths as Natural Tags

Sectioned Otolith at 400x: M. Payne 2012

CalciumStrontiumBariumManganese

Otoliths reflect ambient water chemistry (Campana 2005)

Otoliths as Natural Tags:Require Differences in Water Chemistry

Freshwater:↓ Sr ↑Ba

Seawater:↑Sr ↓Ba

Otoliths as Natural Tags: Field Verification Sr:Ca

0 5 10 15 20 25 30 35 400

1

2

3

R² = 0.68718575068141

Salinity (ppt)

Sr:C

a X1

00

0 5 10 15 20 25 30 35 400

0.02

0.04

0.06

0.08

0.1

R² = 0.606411802104365

Salinity (ppt)

Ba:C

a X1

00Otoliths as Natural Tags: Field Verification Ba:Ca

Research Questions

Habitat Use: ↑Estuary = ↑ Residency

Growth: ↑Estuary =↑Growth

Differences Among Runs: Otolith A ≠ Otolith B

Methods

Study SitesSite Selection

Ken-nebec

St. George

Orland Patten East Machias

0

1000

2000

3000

4000Si

ze o

f Est

uary

(ha)

Rostrum

Postrostrum

Ventral Edge

Dors

al E

dge

1mm

M. Payne 2013

CoreFirst AnnulusFirst Annulus

Otoliths

Otolith Microchemistry Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)

Otolith at 400x - M. Payne 2013

Core (age=0)

1mm

Otolith Microchemistry: Interpretation

-800 -600 -400 -200 0 200 400 600 8000123456

Distance from Core (microns)

Sr:C

a x1

000

Migration PeakFreshwater/ Low Salinity

Migration Peak

Low Salinity Habitat Use Value (LSHU)

<1 = migrated to sea before the end of the first year of growth>1 = migrated after the first year;

overwintered in estuary

LSHU= 0.48

0 100 200 300 400 500 600 7000

2

4

6

Distance from Core (microns)

Sr:C

a x1

000

# of shiftsMagnitude of Sr:Ca

1

3

2

1.65

3.00

4.15

Regime Shifts (Rodionov 2004)

-800 -600 -400 -200 0 200 400 600 8000

1

2

3

4

5

6

Distance from Core (microns)

Sr:C

a x1

000

Otolith Width at EgressOtolith Width at Year 1

Back Calculation: Length at Year 1 and Egress

Back Calculation: Length at Year 1 and Egress

0 200 400 600 800 1000 12000

20

40

60

80

100

120

f(x) = 3.963731781602E-05 x² + 0.0435877125033645 x + 12.971955869558R² = 0.966493250925319

Otolith Width (microns)

Tota

l Len

gth

(mm

)

LSHU

No. of Regime Shifts (Sr, Ba, Mn)

Growth Proxy

Multiple Discriminant Function Analysis

Results

James McCarthy 2013

-900 -700 -500 -300 -100 100 300 500 700 9000

1

2

3

4

5

6Benton FallsDresden MillsWinneganceSeven Tree PondOrland DamPatten PondHadley Lake

Distance from Core (microns)

Aver

age

Sr:C

a x1

000

Habitat Use: Alternative Life Histories

0 100 200 300 400 500 600 700 8000

1

2

3

4

5

6

7

8

9

Distance from core (microns)

Sr:C

a x

1000

Habitat Use: Alternative Life Histories Winnegance

0 1 2 3 4 5 6 7 80

50

100

150

200

250

300

Total Length

Estimated Length Year 1

Estimated Length at Egress

Leng

th in

mm

Bent

on F

alls

Orla

nd D

am

Patte

n Po

nd

Hadl

ey L

ake

Seve

n Tr

ee

Win

nega

nce

Dres

den

Mill

s

Growth: Lengths at Year 1 and Egress

Classification

%correct

Benton Falls 35

Dresden Mills 60

Hadley Lake 67

Orland Dam 35

Patten Pond 50

Seven Tree Pond 26

Winnegance 85

Total 50

Differences Among Runs:Multiple Discriminant Function Analysis

→Growth Proxy →LSHU Value→# Regime Shifts

[Sr: Ca, Ba:Ca, Mn:Ca]

ConclusionsHabitat Use: ↑Estuary ≠ ↑ ResidencyTwo rivers showed habitat use as predicted although overall a correlation with estuary size and distance to sea was not found

Growth: ↑Estuary ≠↑GrowthFish with the lowest LSHU (Winnegance) were significantly shorter at EgressWetland habitat (Mn:Ca) may infer a growth advantage; longer lengths at Egress

Differences Among Runs: Otolith A ≠ Otolith BWinnegance and Patten Pond show alternative migratory patterns compared to other runsOtolith methods are promising in terms of run differentiation

Implications/ Future Directions Otolith microchemistry can be

used to study habitat use in Maine rivers!

Freshwater and estuary habitats are important for recruitment to adult populations

Variation in Ba:Ca and Mn:Ca signatures in freshwater (otolith and water chemistry) could be used to identify origin at a finer scale

Questions?

Zachary Whalen 2013

Length at Egress and Mn:Ca

0 10 20 30 40 50 60 70 80 90 1000

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Benton FallsDresden MillsWinneganceSeven Tree PondOrland DamPatten PondHadley Lake

Estimated Length at Egress (mm)

Max

imum

Mn:

Ca R

egim

e

r = 0.641