Download July, August, and September 2015 Newsletter Infectious Pancreatic

The Fish Pathologist Program was established to work with the public and various agencies to oversee the
health of fish and aquatic organisms in the state of Arkansas.
July, August, and September 2015 Newsletter
Infectious Pancreatic Necrosis at
Jim Hinkle Spring River
Hatchery
Multiple batches of rainbow trout and
even cutthroat trout tested positive for
Infectious Pancreatic Necrosis (IPN) at
the Jim Hinkle Spring River Hatchery
this spring. IPN was detected in the
farm level health inspection and in a
diagnostic case with high mortality rates
in young of the year fish in the hatch
house (Figure 1).
This disease is one that can cause high
mortality in young fish and strikes
usually within the first two months of
young fish accepting a feed diet. The
disease primarily affects young fish but
it can also affect growers on facilities
where it has become established.
Compared to other pathogens, IPN is
much harder to control as it can be
transmitted in the egg and by adult
carriers that can shed the virus without
exhibiting any signs of the disease.
After an initial outbreak, IPN can
transition from an acute illness to a
chronic condition where the fish become
vulnerable to the stress of crowding,
grading, and transport. The virus can be
transmitted via eggs, milt, and
excrement.
Figure 1. Young rainbow trout
exhibiting clinical signs of IPN.
Fish Health Surveys
With the assistance of many fisheries
management and culture staff tissue
samples were collected in August and
September from trout waters across the
state to test for the presence of IPN and
other trout viruses (Table 1). Tissues
collected from trout included both spleen
and kidney from each fish (Figures 2-3).
The tissues are placed in special media
(Hank’s Balanced Salt Solution) during
overnight transport to the fish health
center for processing (Figure 4). Once
samples are received at the fish health
center they are further processed and
placed onto cell lines. Cell cultures
require a minimum of 28 days plus
additional time for confirmation testing.
In addition to the wild fish health
samples, the second round of farm level
inspection samples were collected from
the Jim Hinkle Spring River Hatchery.
The sample consisted of 150 trout,
representative of all size classes on the
hatchery. Currently all samples are
being processed by USFWS Warm
Springs Fish Health Center and final
results should be available soon.
Table 1. Sampling Locations in Trout
Waters in Arkansas for Wild Fish Health
Surveys.
Waterbody
Species
Number
of Fish
Spring River
Rainbow
60
(above
Trout
hatchery)
Spring River
Rainbow
60
(below
Trout
hatchery)
Bull Shoals
Rainbow
50
Tailwater
Trout
Brown
10
Trout
Norfork
Tailwater
Little Red
(outside
hatchery)
Little Red (10
miles
downstream of
hatchery)
Beaver
Tailwater
Little Missouri
Tailwater
Ouachita River
(Blakely Dam)
Rainbow
Trout
Brown
Trout
Brook
Trout
Cutthroat
Trout
Rainbow
Trout
Brown
Trout
Brook
Trout
Rainbow
Trout
Brown
Trout
Rainbow
Trout
Brown
Trout
Rainbow
Trout
Rainbow
Trout
53
21
2
4
38
20
2
44
16
35
25
60
23
Figure 2. Trout wild fish health surveys.
Sentinel Fish
Figure 3. Collecting spleen and kidney
tissues from rainbow trout for virology
testing.
In September the staff at the Jim Hinkle
Spring River Hatchery cleaned and
disinfected the hatch house and prepared
to receive a batch of sentinel fish.
Sentinel fish are a group of test fish that
are the appropriate age, size, and species
to be susceptible to the pathogen of
concern. These fish were brought from
an IPN negative facility to the Jim
Hinkle Spring River Hatchery. To
ensure the fish were free of disease fish
health samples were collected from the
fish on the truck prior to entering into
the hatch house and hatchery water.
Once offloaded onto the hatchery the
fish remained quarantined in tanks in the
hatch house for a period of three weeks.
At the end of the three week period fish
health samples were again collected for
analysis to determine if IPN could be
detected. The fish have recently been
moved out of quarantine and into a
raceway on the culture facility. Fish
health samples will again be collected
from the sentinel group in approximately
three weeks. It will be November and
early December before all the testing
results for the sentinel fish will be
completed.
Biosecurity
Figure 4. Placing trout tissue samples in
Hank’s Balanced Salt Solution for
shipping to fish health center.
Having a good biosecurity program is a
key component for any fish culture
facility to prevent the introduction,
manage the occurrence, and prevent the
spread of any disease. Diseases are a
part of the culture of any living organism
and provide challenges on any type of
culture system. Staff must be aware of
the clinical signs of disease, how it is
spread, and follow best management
guidelines are in place to prevent
introduction of pathogens into
the hatch house. In many cases
fish can range from a few days
old to several months in age
when they move out of the hatch
house. There are several
pathogens that primarily target
young fish (9 months and
younger) so it is important to
keep these fish as protected as
possible. So remember if there is
an area that is posted off limits
due to biosecurity, it is only to
protect the young fish from
pathogens so our staff can
provide the best fish for the
resource!!!
practices to limit the impacts of a disease
on the culture population. With the
identification of IPN and largemouth
bass virus (LMBV) on AGFC culture
facilities a thorough review, drafting,
and revision process of biosecurity
protocols in underway. Each facility
will have a biosecurity plan tailored to
the facility based on needs, threat
potential, and feasibility. Cleaning and
disinfection protocols are a major
component of any biosecurity plan.
These plans encompass all fish culture
activities starting from broodstock
selection and egg disinfection to
cleaning and disinfecting the fish truck
after stocking fish. Activities by staff
are not the only pathway for pathogens
to enter the culture facility.
Visitors to fish hatcheries are always
encouraged and promoted; we love for
people to see and understand what we do
and how we do it!!! By following some
simple guidelines visitors to hatcheries
can learn some incredible facts about
culturing fish and be part of the
biosecurity program. Important
information for visitors to a fish hatchery
to remember:
1. Keep your hands out of the water
please- many parasites and
pathogens can be transmitted by
simple actions like putting your
hands in one tank and then
another tank without washing
them. Although these pathogens
are not likely to make us sick
they can be detrimental to fish in
other tanks.
2. Young fish are susceptible to
many diseases- a hatch house at
the hatchery is like the nursery at
the hospital. Strict biosecurity
3. Look for biosecurity signs- many
times there are biosecurity signs
posted around that hatchery.
Often times there are signs about
foot baths, hand washing, and not
bringing personal fishing gear
(rods, boots, waders, and etc.)
onto the culture facility (Figure
5). Many of the fish culture
buildings will have foot baths
that you must walk through when
entering and exiting the building.
These are filled with disinfectant
and used to minimize the ability
of pathogens to hitch a ride from
one part of the facility to another.
4.
Many AGFC hatcheries are
located near fish areas or access
areas and often anglers will stop
by and visit the hatchery while in
the area. It is important to
remember that a disease in the
wild and a culture system do not
have the same impacts. A
disease in a culture system where
fish are in close contact with one
another enables a disease to
spread much faster than in a wild
fish population. In some cases
the only way a hatchery can get
free of an established disease is
to destroy the fish and start over
with new stock.
We look forward to all of our visitors
and tour groups each year that take time
to see our great facilities!!!! Thank you
all for doing your part to help protect our
resources!!!!
Figure 5. Foot bath and hand washing
biosecurity sign at hatchery.
Contact Information
In case of disease problems, fish kills, or
disease questions please contact:
Kelly Winningham
Fish Pathologist
Andrew H. Hulsey Hatchery
350 Fish Hatchery Road
Hot Springs, AR 71913
Ph (501) 525-8606
Fax (501) 525-2265
[email protected]