Thursday, November 29, 2012

Another Great Externship

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: 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

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