Mortality in Atlantic Salmon (Salmo salar) Associated with Trichodinid Ciliates Author(s): R. A. Khan Source: Journal of Wildlife Diseases, 27(1):153-155. Published By: Wildlife Disease Association DOI: http://dx.doi.org/10.7589/0090-3558-27.1.153 URL: http://www.bioone.org/doi/full/10.7589/0090-3558-27.1.153

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Journal

Mortality

in Atlantic

Trichodinid R. A. Khan,

(Salmo

salar)

of Biology A1C 5S7

and

Ocean

Sciences

Associated

Centre,

Memorial

foundland, L, depth

100

signs

were

Atlantic

listlessness,

appetence.

cus

The

secretion,

erratic infection

epithelial

swimming

and

induced

excessive

sloughing

and

ing,

in-

mulesions

Canada

fed

in tanks to March)

and

Pen-

(Hoskins

et a!., Recently, (Salmo

1984).

salmon inated

from

foundland, after being

Examination gills

this

effective Thirty

(Noel

of smears

The purpose is to report (1) the

the

by

fish, infection

method of control. six adult Atlantic

(2) and

the

Sciences Centre, of Newfoundland,

Memorial St. John’s,

rest

of the

At

1.5 in

salmon a loss

signs

against

UniNew153

he-

walls

whitish

recognized

the with

body, others an opaque

to the

pustules

slen1988), water of

while rub

by

their

evidence

bodies

of

a deindividual

by

was

a tendency

the

thick

with

in spring (May rise of the

their

had

a few

fixed

by con6 tm

some

was

the

There

fish

in

was

capture, in

This

of

the

skin

as indicated

It occurred with

and

were

hematox-

stained

following

occurred.

ming

kelts,

others iron

methods;

intake

of weight

rotation

Some Klein’s

processed

and

the

line.

eosin. yr

temperature.

an

and

de-

as modified

affected

food

der shape. concomitant

were from using

(1969);

cut

eshemo-

lateral

Heidenhein’s

and

About

intensities,

stained

histological

crease

and

technique

were

ex-

infection

Laird

dead

x 24 mm

obtained

formalin

matoxylin

or

a 24

the

necropsy,

sections

live

a Neubauer

were

and

ventional

of

below

with

in buffered

about 53 cm in length, were obtained in central Newfoundland (47#{176}52’N, 56#{176}20’W) in October 1986 and held in the laboratory (Ocean versity

the

microscopic

ciliate

smears

Lom

tial salmon

varied (January

with

mucus

impregnation

ylin.

in-

(3)

,

from

of

of the

stained

skin

of this communithe occurrence

me-

a vitamin sup1987) ad libitum

for

means

region

silver

in New-

tnichodinid

in a sa!monid with

in

smears

from

trunk

trout Canada

from

intense

by

termined

salmon

Paul’s)

They

(Menidia

6 to 16 C for

Prevalence

timated

in eastern Canada, died for a period of about 8

revealed

ciliate

associated

a

1,800

8L/min).

0 to 4 C in winter

prepared

covenslip.

Arthur and Margolis, number of Atlantic kelts which had orig-

salar)

located held

mo.

fections. cation

1976;

a brook

and

to Pacific and steelhead in western

in self -clean-

(capacity

temperatures

by scraping

air dried

spp.)

with et al.

gill

were

species have been reported from and one (Trichodina truttae), is pathogenic

rate

Water

and

Skin

cytometer,

(Oncorhynchus (Salmo gairdneri)

flow

St. John’s,

year.

tnichida) are ectoparasitic ciliates that occur on the skin, fins and gills of fish and occasionally cause disease in cultured freshwater fish (Hoffman, 1967). Several

hatcheries,

557)

silversides

from

amination

sa!monids noted

cm,

weekly.

fish (Ci!iophora:

A1C aquaria

impregnated (Johnston

thrice

tality.

of Trichodina

of Newfoundland,

flow-through

nidia) plement

that probably permitted entry of opportunistic bacteria which eventually caused ulcers and death. A seawater bath for 30 mm each week for 4 wk effectively controlled the parasite. Key words: Trichodina truttae, ciliate, ectoparasite, Salmo salar, Atlantic salmon, mor-

Species

27(1), 1991, pp. 153-155 Disease Association 1991

with

University

A protozoan infection (Trichodina truttae) was identified in captive Atlantic saimon (Salmo salar) kelts that died in spring of 1988 and 1989. Fish with intense infections showed ABSTRACT:

of

DIseases, © Wildlife

Ciliates Department Canada

Newfoundland,

Salmon

of Wildlife

par-

swim-

themselves

aquarium.

Some

at intervals

along

appeared to be coated film of heavy mucus, and

skin

was

eroded

and

open

JOURNAL

154

OF WILDLIFE

DISEASES,

VOL. 27, NO. 1, JANUARY

1991

hemorrhagic lesions were apparent. Affected fish also were listless. Microscopic examination of the whitish pustules and opaque films of mucus from nine salmon which died revealed numer-

foundland. the ciliate

ous

cause

tnichodinids.

The

latter

served on salmon with and were accompanied of rod-shaped

bacteria.

salmon examined with tnichodinids.

also

In

Sixteen

spring in only

ob-

lesions numbers of 27

in 1988 were One had an

infection of 1 x 10 organisms/ml; others the intensity exceeded 1 In all cases the intensity of the was consistently greater on the on the gills. were observed

were

hemorrhagic by large

plasia

lesions lesions.

accompanied

mortality. confinement ing winter

and excessive mucus served in salmon with infections. (s0.5 cm

Purulent in diameter)

from colorless accompanied sponse. These fections

in

dence layers and

secretion intense and

was trichodinid

ulcerated on the trunk

some

become

fish.

There

in the epithelium infected

was

lesions varied were reinno

evi-

subcutaneous was eroded with

bacteria.

1988 After

of about 5 L/min for the flow of freshwater.

this was performed this period, none

weekly of the

0.5

hr In

for 4 wk. remaining

14 fish had the trichodinid infection on the skin or gills. On reappearance of the infection in 1989 the treatment was repeated, with no subsequent appearance of the parasite. The

presence

of trichodinids,

tentative-

unidentiinfections cause

of

stress

induced by food intake dunimpaired host re-

through tnichodinid

elevated coninfections.

tnichodinids

could caused mucus

erosion permitted bacteria which

have

in-

epithelial secretion. entry of the ultimately

caused mortality. This scenario of corticosteroid-induced stress having a suppressive effect on the defense systems and subsequent injury in fish by tnichodinids has been reported previously (Lom, 1973; Pickering and Pottinger, 1989). I am grateful to L. Cnim for permission to

sample

the

viewing

the

Sciences

and

Atlantic

salmon,

James to

to

for typing W. Threlfall

manuscript

and

Engineering

cil of Canada for Ocean Sciences Number 93.

financial Centre

LITERATURE

Ms.

drafts for

to the

S. of re-

Natural

Research

Coun-

support. This Contribution

is

CITED

J. H., AND L. MARGOLIS. 1984. Trichodina truttae Mueller, 1937 (Ciliophora: Penitrichida), a common pathogenic ectoparasite of cultured

ARTHUR,

salmonid

fishes

tion and

examination Canadian

croscopy.

in

British

Columbia:

Hedescrip-

by scanning electron miJournal of Zoology 62: 1842-

1848. HOFFMAN,

G. L.

freshwater

ly identified at T. truttae, in a native population of Atlantic salmon suggests that the parasite is endemic on the island of New-

that

in intensity and and excessive

Kenny and M. the manuscript,

A seawater bath appeared to be an effective method of control for the tnichodinid infection. The volume of freshwater in the aquarium was reduced to 50% and running, ambient seawater was introduced at a flow rate before resuming

the

some

at necropsy. subcutaneous

view

I suggest that and reduced might have

Epithelial opportunistic

ob-

because

bacterial the underlying

sistance, mediated tiso! levels, to the Thus,

salmon

the

opportunistic have been

creased sloughing

sloughing

to a pale pink and by an inflammatory lesions also had bacterial

of tnichodinids where the had

cellular

in the

grade infections of ulcers and

supports

in three x 10/ml. infection skin than

were compatible Epithe!ial hyperby

bacteria fled might

died. M icroscopic with the gross

of death had low presence

infected estimated

1989, tnichodinids 12 of 15 salmon that

of to

date, this is the only fish host in which the parasite has been observed. It appears unlikely that the parasite was the primary fish The

live

This also is the first report in S. salar in eastern Canada;

1967. fishes.

Parasites University

of North

American

of California

Press,

Berkeley, California, 486 pp. HOSKINS, G. E., G. H. BELL, AND T. P. T. EVELYN. 1976. The occurrence, distribution and significance

of

served

in fish

infectious in the

diseases Pacific

and Region

neoplasms up

to the

obend

SHORT

of

1974.

Fisheries

Development Federal

and

Technical

Department

Marine

Service

Research

Report 609, Canadian of the Environment, Otta-

wa, Ontario, 37 pp. JOHNSTON, C. E., H. W. GRAY, A. MCLENNAN, AND A. PATERSON. 1987. Effects of photopeniod, temperature, and diet on the reconditioning response, blood chemistry, and gonad maturation of Atlantic salmon kelts (Salmo salar) held in freshwater. Canadian Journal of Fisheries and Aquatic Science 44: 702-711. LOM, J. 1973. The adhesive disc of Trichodinella-

Ultra-structure

and

asitologica

20:

AND

from

M.

marine

COMMUNICATIONS

injury

to the

host.

155

Folia

Par-

193-202. LAIRD. and

1969. euryhaline

Parasitic fish

of

protozoa Newfound-

I. Penitrichous ciliates. of Zoology 47: 1367-1380. PICKERING, A. D., AND T. G. POTTINGER. 1989. Stress responses and disease resistance in salmonid fish: Effects of chronic elevation of plasma cortisol. land

and

Canadian

Fish

Received

New

Brunswick.

Journal

Physiology

for

publication

and

Biochemistry

7: 253-258.

6 December

1989.

Mortality in Atlantic salmon (Salmo salar) associated with trichodinid ciliates.

A protozoan infection (Trichodina truttae) was identified in captive Atlantic salmon (Salmo salar) kelts that died in spring of 1988 and 1989. Fish wi...
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