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.