Distribution of the swimbladder parasite Anguillicola crassus in

American eels in the Northeastern Atlantic

University of Massachusetts Dartmouth

Department of Biology

Amy Aieta&

Kenneth Oliveira

Life History of Anguilla rostrata

Silver phase

EggLeptocephalus larvae

Glass eel/Elver

Yellow phase

L2 Released

Intermediate Host

L2 molts to L3

Intermediate/Paratenic Host

Ingested by Eel

L3-L4 swimbladder wall L4-L5 swimbladder lumen

The life cycle of Anguillicola crassus

Biogeography of Anguillicola crassus

•Identified in Southeast Asia 1974 •(Anguilla japonica)

•Early 1980s introduced to Europe •(Anguilla anguilla)

•1995 found in North America• (Anguilla rostrata)

Occurrence of A. crassus in North America

1995 Texas (TPWD; Moravec)

South Carolina (Fries et al. 1996)

Chesapeake Bay (Barse and Secor 1999; Barse et al. 2001)

Hudson River (Barse and Secor 1999)

2003 N. Dartmouth, MA

Objectives

1) Determine northern extent of parasite range in USA

2) Examine prevalence & intensity within NE

3) Examine effects of parasite/eel interactions

MethodsNortheastern Distribution

Yellow eels *

•Summer 2005

Southern Sampling Survey

•CT, RI, S.-MA

Northern Sampling

•N.-Ma, NH, ME

n=13

n=10

n=3

Collection of Yellow Eels in Freshwater

Collection of Silver Eels

• Eels euthanized w/Clove oil

• Weighed/length measured

• Parasites counted

• Parasite length measured

Preliminary Analysis

Analysis

Prevalence Example 30%

infected

Mean Intensity1.67 parasites

Results

69%

35%

28%

Prevalence of Infection: Rhode Island

N. KINGSTON

7%

33%62%

76%

16%

52%21%

58%64%33%

Prevalence of Infection: Massachusetts

NEW BEDFORD

PLYMOUTH

BOSTON

0%31%0%

0%0%0%

Prevalence of Infection: Maine

BANGOR

PORTLAND

0%

26%

35%60%

58%65%

53%

Kennebec RiverEstuarine eels

n = 315

Eel Size Class (cm)

<10

10.1

-15.

1

15.2

-20.

2

20.3

-25.

3

25.4

-30.

4

30.5

-35.

5

35.6

-40.

6

>40.

6

Mea

n P

aras

ite

Inte

nsi

ty

0

2

4

6

8

Log 10 Eel Length

1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0

Lo

g 1

0 E

el W

eig

ht

-2

-1

0

1

2

3

4Nonparasitized r2 = 0.99 (n = 523)

Parasitized r2 = 0.98 (n = 315)

Silver Eel Data: Paskamansett River

Year Prevalence Mean Intensity2003 28% 2.9

2004* 52% 5.8

2005 ? ?

SignificancePrevalence: Fischer's Exact Test p = .008

Intensity: T-test p = .007

Conclusions

Current Northern Limit

• Sedgeunkedunk Stream, ME • 44°45.306N, tributary of the Penobscot River

• No latitudinal trend• Possible ballast water introduction

• Temperature: not an apparent limiting factor

Influences of Parasite

• All size classes infected• No apparent detrimental effects on eel weight/length• Suspected negative impact on migrating silver eels

Questions/Discussion