Hello! I’m Christina, a fourth year veterinary student from
Colorado. You might recognize me from last winter when I spent two weeks at the
Idaho Fish Health Center (IFHC) learning all I could about keeping Idaho’s
salmon and trout disease free. The passion and enthusiasm of the veterinarian
and biologists at the IFHC was extremely contagious, and I decided then and
there that I wanted to pursue a career in fish health. So after getting my feet
wet in December I decided to return this past August to go in waist deep…
literally!
Wild Fish Health Survey:
Every summer fisheries biologist Laura Sprague and a group
of volunteers go into the field to collect wild fish from creeks all over the
state of Idaho. The goal of these
expeditions is to assess the prevalence of important fish pathogens in native
fish populations, to identify the bacteria, viruses, and parasites infecting
our wild fish and to measure how widespread the pathogens are. This is done by collecting
the heads, bits of spleens and kidneys from a previously determined number of
wild fish from each stream chosen. These tissues are brought to the fish health
laboratory and tested for important pathogens. Examples of these pathogens are
the causative agents of Whirling Disease (Myxobolus
cerebralis), Bacterial Kidney Disease (Renibacterium
salmoninarum), and Infectious Hematopoietic Necrosis Virus (IHNV). The
great thing about the Wild Fish Health Survey is that it generates data
biologists use to detect the onset of fish diseases early. Since the survey is performed every year, we
can detect subtle changes, such as a slight uptick of a certain
bacterial pathogen in the trout population or the spread of a parasite into
previously pathogen free waterways. Early detection of these changes helps us
create policies to prevent further pathogen spread to keep wild and
hatchery fish safe. Technically speaking we’re collecting samples to quantify pathogen
presence in a population (surveillance) to assess and interpret spread of pathogens
among individuals of the population (epidemiology).
Another great characteristic of the Wild Fish Health survey
is that it’s a national project. Fisheries biologists all over the country are doing
exactly what Laura is doing and submitting their findings to a national
database. You can go to this website: http://ecos.fws.gov/wildfishsurvey/database/nwfhs/
and learn what pathogens have been detected in your favorite waterway wherever
you are in the United States.
The day after I arrived, Laura and I drove a few hours north
of Orofino and joined two other fantastic volunteers in the Ponderay area for
fish sampling. What followed was four days of tramping around in cool, clear
creeks deep in the forest. We scrambled over little waterfalls and skirted
around deep sandy pools to find hidden fish. In all we electrofished over two
dozen brook trout, sculpin, and the odd rainbow trout. At the end of the day we took the fish back to
our hotel to necropsy, saving the kidneys, spleen and heads for laboratory
testing.
I highly recommend going wild fish sampling with Laura for
anyone interested in volunteering at the hatchery or fish health center. It’s
probably the most fun I’ve had all year!
The laboratory and beyond:
During my second week at the Idaho Fish Health
Center I spent time in the laboratory learning how to detect common viruses,
bacteria, and parasites in our hatchery fish. I also got to venture into the
wilderness again learning how to identify redds (salmon nests) in Newsome creek
and find spring Chinook salmon that had returned to spawn. It would take pages
to describe everything in words so here are some pictures to help move this
entry along!
This is a picture of a fish with Bacterial Kidney Disease
(BKD). A normal fish would not have the gray lumps on its kidney (blackish
organ near the spine) that this fish has. This fish was probably quite sick
before it was euthanized! Dr. Blair,
IFHC’s fish veterinarian, guided me through the process of performing an ELISA
test (Enzyme Linked Immunosorbent Assay) to detect the organism that causes BKD
in fish kidneys. IFHC performs these ELISAs to reduce the incidence of BKD in
Idaho’s hatchery raised salmonids. BKD can be transmitted from a female spawner
to her eggs and among adult fish. To stop the transmission of BKD as early as
possible we test for BKD in adult females that we’ve spawned. We then cull
their eggs if they test positive to insure that all eggs mature into adult
salmon and trout as BKD free as possible.
In
this picture I’m taking kidney samples from a female spring Chinook salmon
during spawning at the Nez Perce Tribal Hatchery. We took these samples along
with samples of ovarian fluids and brought them to the lab to analyze for
common fish pathogens. Whenever I ask staff at any hatchery what their favorite
part of the job is, they almost always say “spawning.” It’s a fast paced
morning of hard work, but there’s always a little time to catch up with old
friends and colleagues. There’s also something
wonderful about being a part of an event like this, something that marks the
end of one generation of these ancient fish and the beginning of another.
This is a female spring Chinook salmon guarding her redd in
Newsome Creek, about two hours from Orofino. See how beaten up her tail is? The bottom
part’s missing and it’s almost gone white. She’s been swishing it back and
forth, using all her energy to move dozens of stones larger than her head into
a special configuration. Her goal was to create a safe and well ventilated nest
for her eggs. Although she’s laid somewhere between 2,000 and 7,000 eggs, only
a very small percentage will survive to migrate back to the ocean. A day or two
after this photo was taken she probably died, her body providing essential
nutrients for the flora and fauna of Idaho’s forests.
I was lucky enough to spend a day of my second week with
Laura’s husband Sherm, a fisheries biologist for the Nez Perce tribe. We spent
the day counting redds, charting their locations along the creek, and
collecting biological data from fish that had already spawned in Newsome Creek.
This is done in order to better understand the characteristics of the
wild-spawning spring Chinook population. We can figure out, for instance, how
many fish are returning to the creek, whether these fish were born in the wild
or at a hatchery, their genetic background, and how old they are. This gives us
information on how to better support these populations.
It’s thrilling to observe these fish spawning in the wild,
whether they’re racing upstream over rills, waiting quietly for other salmon in
a deep pool, or lying exhausted over a completed redd. Knowing how far these
salmon have come, how many obstacles they’ve faced, and the sacrifice they’ll
make in order to ensure the survival of the next generation is also inspiring!
Once again I had a wonderful time at the Idaho Fish Health
Center, whether it was in the lab, at the main hatchery or in the field. Many thanks to Laura, Sherm, Guppy, Corie, Liz
, Chelsea, and the staff at the Nez Perce Tribal Hatchery for teaching me so
much about fish and making me realize how much more there is to learn!
By Christina Der
By Christina Der
