Hello! My name is
Johnny Shelley and I am a 4th year veterinary student at Louisiana
State University School of Veterinary Medicine.
I had the good fortune to just complete a four week clinical externship
at the Idaho Fish Health Center and Dworshak National Fish Hatchery, and I
wanted to share some of the experiences I had while visiting the beautiful
northwest for the first time.
I am actually a veterinary student odd ball in that I went
to veterinary school with the sole intention of specializing in the area of
aquatic animal medicine with an emphasis in fish health. I wanted to make sure that during my clinical
rotations I was exposed to a variety of different aquatic animal health
settings since I don’t know where my career may take me. I initially contacted the Olympia Fish Health
Center about doing an externship that specialized in the area of cold water
fish diseases. Fortunately for me their
availability did not fit mine, so they suggested that I should contact the
Idaho Fish Health Center. After
contacting the center I got a quick response from the center’s veterinarian, Dr.
Marilyn “Guppy” Blair, and she was very receptive to my coming out to learn and
work. It turns out that I lucked out by
doing my externship at the Idaho Fish Health Center because it is not only on
the grounds of the Dworshak National Fish Hatchery, but it is also works very
closely with various Nez Perce Tribal hatcheries and acclimation sites.
I drove into Orofino/Ahsahka on April 22nd and I
was immediately captivated by the beauty of the land and the unique location of
the Idaho Fish Health Center. On my
first day at the center I was immediately welcomed in and treated as a part of
the team. After learning a little bit
about the wild fish health survey that is annually conducted at the fish health
center from fish health specialist Laura Sprague, she took me to the Nez Perce
Tribal Hatchery at Cherry Lane to do monthly monitoring on their Fall Chinook
Salmon. Monthly fish health check
monitoring is done at all Nez Perce hatcheries and acclimation sites, in
addition to being conducted at the Dworshak Hatchery, to ensure that disease
does not run rampant prior to release, as well as minimizing the release of
fish carrying disease in to the wild.
During health checks, gill clips and skin scrapes are taken to look for
possible parasites and infectious bacteria.
Additionally, fish necropsies are performed to observe any potential
abnormalities and samples of the spleen, kidney and gill are taken for viral
and bacterial monitoring. I was able to
travel to Kooskia National Fish Hatchery with Dr. Blair to perform health
monitoring on the spring Chinook salmon that are held there. I also traveled
with fish health specialist Rick Cordes to the North Lapwai Valley acclimation
site to pick up Fall Chinook Salmon sub-yearlings to bring back to the lab for
their health check.
Dr. Blair showed me
how to perform enzyme-linked immunosorbent assays (ELISAs), which are screening
tests for disease where specific antibodies are used to detect for the presence
or absence of a specific antigen.
Enzyme-linked secondary antibodies are also added to the samples along
with a chemical that is converted by the enzyme into a color if the sample is
positive for the antigen. The presence
and quantity of the antigen can be measured by light absorbance through a
spectrophotometer. ELISA is
predominately used at the Idaho Fish Health Center to detect for the presence
of Renibacterium salmoninarum which is the
causative agent of Bacterial Kidney Disease.
During my stay I also learned about the methods that are utilized
to detect viruses in aquacultured fish.
The center’s virologist, Corie Samson, showed me how they culture cell
lines which are used to check for the presence or absence of viruses, primarily
infectious pancreatic necrosis (IPN) and infectious hematopoietic necrosis
(IHN) viruses. I also learned the
methods for viral plating and extractions.
Fish that are positive for viruses are culled from the population and
the samples are sent off to another laboratory to determine the specific
genetic viral strains. I also was able
to expand on my knowledge of quantitative and nested polymerase chain reaction
(PCR) tests through the tutelage of both Laura and Rick. The basics of PCR are that it is used to
amplify a specific region of a DNA strand and in fish health can be used to
detect and/or identify bacteria and viruses from tissue culture assays. I also was shown by Rick how surveillance is
done for Nucleospora salmonis and Myxobolus cerebralis which is the
causative agent of whirling disease.
Whirling disease can cause bone destruction and it is detected by
digesting the skull bones of fish and looking for M. cerebralis spores in the dissolved “skull soup” that is left
over. Definitive diagnosis of whirling
disease and many of the other cold water fish diseases can be done by
histology. Histology is the study of
microscopic anatomy of cells and tissues, and is commonly performed by
sectioning and staining samples on glass slides so that they may then be
observed through light microscopy. Dr.
Blair took the time to show me how the process of preparing a histology slide
is conducted and even let me attempt to section some tissue samples for myself. Additionally I was able to go through a
histology slide set and observe various normal tissues and tissues that were
infected with common bacteria and viruses.
In addition to my duties in the health lab, I was also able
to take part in other activities at the Dworshak Hatchery and in the surrounding
communities. On one of my Saturdays I
was able to take part in some of the fish production duties that are conducted
at the hatchery. I spent my morning in
the hatchery with fish culturist Rick Allain where he showed me how to do
hourly feedings and raceway cleanings for the steelhead fry. I spent my afternoon with the hatchery
manager Mark Drobish, where he showed me how they feed and clean the raceways
for the Fall and Spring Chinook Salmon fingerlings. He also took me around and showed me how the
water is pumped into the hatchery facility, and how it is degassed and
maintained in order to rear healthy fish.
I think both Rick and Mark had confidence in me in the fact I was a
veterinary student who had prior knowledge and experience with fish, which I
guess is not the norm for externing students, because both of them left me to
my work without really hovering over me or double checking everything I did. I also was able to be a part of a couple of
outreach opportunities, which I understand can be very important in getting
community support. I went with Dr. Blair
and Corie to Kamiah Elementary where we talked to the 5th grade
classes about what the Idaho Fish Health Center does and we went over basic
fish anatomy. Afterwards the students
got to split up and we helped them conduct their own fish necropsies, which
they seemed to love. I also got to take
part in the annual Kid’s Fishing Day, which I think is a wonderful way to give
back to the community and say thank you for their support. It truly is wonderful to see a child’s face
light up when they catch their very first fish.
During the health monitoring of the fall Chinook salmon, conducted
at the Dworshak Hatchery, it was noticed that some of the fish were showing a
sickle cell appearance of their red blood cells. Sickle cell in fish has been attributed to
folic acid deficiency, anoxia, and lead toxicity. At the time the raceway of fish were not showing
any other visible signs of illness either internally or externally other than
some had slightly hemorrhagic and edematous intestines, and it was not believed
that any of the above mentioned possibilities were the cause . The day before I was to leave we were called
back to check on the same raceway because some of the fish were showing erratic
swimming behavior and appeared to have external “grayish white” lesions on
their heads. We collected some of the
fish that were indeed swimming in a lethargic and upside down manner, as well
as had the visible lesions. Upon closer
examination the lesions were determined to be a fungus, which was as yet
unidentified when I had to leave. Some
of the fish were also still exhibiting the sickle cell shape of their red blood
cells. Unfortunately for me, I had to
leave before a definitive diagnosis could be made. As with all of the fish health monitoring
checks we took samples for bacteriology and virology, and since I plan on
keeping in touch with the staff at the Idaho Fish Health Center hopefully I
will be able to find out what the definitive cause is.
I
truly had a wonderful time and amazing experience during my stay in Idaho. I certainly hope to stay in touch and
hopefully I will be able to come back out for a visit. Lastly, I would like to say thank you to
everyone I met at the Idaho Fish Health Center, Dworshak Hatchery, and all the
Nez Perce Tribal Hatcheries that I visited.
I would especially like to say thank you to Dr. Marilyn “Guppy” Blair,
Laura Sprague, Corie Samson, Rick Cordes, Liz Steiner, Chelsea Weeks, Rick Allain,
and Mark Drobish. It’s funny because I guess there was some talk as to how the
center was going to be able to come up with enough for me to do for four weeks,
but as you have read from my ramblings I had plenty to do and I had a blast
doing it! Thank you everyone and until
we meet again!
