Malina Loeher on Fish Diseases and Sustainable Food Systems

Juvenile rainbow trout in a small tank. (Photo credit: Malina Loeher)


I met Malina Loeher when we were both taking a summer course at Friday Harbor Laboratories as new graduate students. The course was on the ecology of infectious marine disease, and Malina is a disease ecologist now finishing her second year as a master’s student at the Virginia Institute of Marine Science (VIMS). Before VIMS she worked for California’s Department of Fish and Wildlife and the UC Davis One Health Institute at Bodega Marine Laboratory, trying to work out the mechanics of withering syndrome in the critically imperiled white abalone. She now studies infectious hematopoietic necrosis virus (IHNV), a pathogen that causes mortalities in salmonids, including commercially farmed species.

Malina is young, but her glasses, the seriousness of the subject we’re discussing, and the thoughtful, clear focus she has while speaking makes her seem light-years ahead in maturity and wisdom, like someone who is used to waiting patiently for her peers to catch up to her. She speaks thoughtfully, with a gentle, warm voice. If you didn’t know her, you would never guess that she, out of a group of energetic graduate students, would be the one to calmly walk into the frigid waters off the coast of San Juan Island and lazily swim around looking for beautiful pebbles to collect, while the rest of us stood chained by fear on the shore, shrieking whenever the bitterly cold waves went any higher than our ankles.

Malina and I spoke twice about her research, once last year and again this year, and we covered a wide range of topics. For this first installment, Malina reflects on her research and her motivations, including her interest in sustainable food. Malina’s words have been edited for length and clarity and are presented below as a single, continuous narrative.

I work in a refrigerated box most of the time, but it probably has a fancier name like “climate controlled wet laboratory.” If you’ve ever seen a restaurant’s walk-in freezer or refrigerator, that’s kind of what I work in. You could call it a refrigerated library, too, but on a really small scale, if you had a library the size of your bedroom and every bookcase had hundreds of fish tanks on it instead of books. For my research, I run experiments with hundreds or thousands of fish in very controlled environments.

The workspace of a fish disease researcher: a refrigerated box full of shelves upon shelves of fish tanks. (Photo credit: Malina Loeher)


Last summer I ran my first set of experiments with sockeye salmon, looking at fourteen different viruses and their phenotypic metrics. For a virus, a phenotype is how it affects the host, which in this experiment is basically if it kills the host or not, and how many new virion particles are being shed from the host. During an experiment, the regular maintenance can usually be handled by a single person per day, including tasks like checking all your fish tanks, monitoring temperature and dissolved oxygen levels, and removing dead fish to keep the tanks clean. Stuff like that. But some tasks needed to be timed very carefully, and so I might spend anywhere from one to five hours per day taking care of an experiment.

A lot of projects that answer similar questions usually only run for about thirty days, but since we didn’t really know how much variation we are going to see and needed a really complete data set from the sockeye salmon in order to be able to do subsequent work, we extended the timeline and tried to do something closer to a sixty-day experiment. That was to make sure that we captured all the time points and saw how long we needed to run our future experiments. On really heavy work days normally we’d have two people assisting each other to make the work go faster, but in the pandemic we tried to eliminate the need for a second person on any given day. Even though it would be ultimately useful to train a person, at the time it was a health risk we didn’t need to take, so I ended up pretty much taking care of a sixty-day experiment by myself. That left me really fried by the time fall semester rolled around, which definitely contributed to being mentally exhausted while going through my classes.

I’m one of the few people that works on a freshwater system at VIMS in a controlled lab environment, and IHNV is a virus endemic to the Pacific coast. That means seminar talks and even classroom introductions are a little different because I have to remind people that I don’t work on a host-pathogen system that’s in our immediate surroundings. In some ways it prevents me from feeling like I’m connected to the community. It’s taken me a little while to figure out what kinds of outreach I can personally do in a meaningful way, and it feels like my options are somewhat limited to things that are virtual.

On the other hand, IHNV is actually a worldwide disease, partly as a function of the expansion of aquaculture. That’s not necessarily because people have been irresponsible in the past, but just because it’s really difficult to contain viruses, as we have seen this last year. You can have the best practices, but things just don’t always go as planned.

We get most of our trout from fish farms that are pretty close by. I don’t know if IHNV is present in those particular farms, but it’s definitely considered a major health concern for any trout system, so it doesn’t really matter if it’s a “West Coast” disease because the threat of IHNV doesn’t really lie so much in its endemic environment, but in these artificially constructed environments that humans have placed across the world.

Malina works in a laminar flow hood to prevent contamination of samples. In this photo she’s dividing a flask of fish cells, which she uses for diagnostic tests. (Photo credit: Malina Loeher)


We’re kind of beyond looking at IHNV in its natural endemic settings in the Pacific Northwest because in the future that may not be where the biggest problems are. This is a virus that has co-evolved with its ancestral host for who knows how long—thousands of years, probably. It’s not an emergent disease in sockeye salmon, which are primarily managed via hatcheries and not commercially farmed, but it is in rainbow trout and other species that are farmed pretty intensely. The reason we included sockeye salmon in these experiments is to establish a baseline for the viral phenotypes in the ancestral hosts, so that we have something to compare to our rainbow trout data.

One of my research questions also asks whether the virus’s specificity has changed over time. Ultimately, this project is examining how a virus has changed over time and the fish are just a necessary part of the virus’s environment. For example, COVID-19 epidemiologists are looking for a source of the virus, and future work on that system will probably include considering wild origins as well as how strains have evolved in humans.

I have to give that background often: Yes, this virus isn’t “from here,” and you may not be familiar with these fish, but that doesn’t matter anymore.

I’ve been thinking about how I can expand on my work to come up with actual, tangible solutions for farmers or managers, because that’s something that I’m really interested in doing. Maybe this will happen down the road, but I think my research and this question are maybe a little too far apart to bring together right now in one dissertation. We have almost no empirical data for how viruses evolve in aquaculture, and aquaculture is a big industry that will only get bigger. We’re going to have more problems down the road if we don’t figure out how to tackle this issue now. It’s a lot of big picture stuff that feeds into a relatively narrow research question.

It’s really interesting to consider how disease ecology works not only into management of fisheries and endangered species and conservation and restoration, but also thinking about sustainable food for humans on a really long-term scale. I really enjoy conservation and natural ecosystems, but I really like food too! I want to continue working towards more sustainable food sources as our population expands and as the climate changes.

Thinking about how to make aquaculture a more sustainable industry at both the long-term, global level and the small-scale, individual farm level are all concepts that guide me forward in how I think about my long-term career goals. The projects that I work on right now don’t really have any direct connection to fish farms. I use farmed fish to do experiments, but the work that I’m producing on a weekly or even yearly basis doesn’t immediately help fish farms, and so that’s something that I still struggle with a little bit. In the future, any postdoctoral opportunity where I would get to work a little bit more hands-on with aquaculture systems would be really fun, but that’s really down the road for me.

Sustainable food doesn’t really directly feed into my work right now, but it is something that guides my personal priorities: on an individual level, I try to make good food choices. I can’t do it all the time because I’m also on a budget, but I think about it a lot and I talk about it a lot. Sharing recipes about seafood I have access to in the Atlantic, like tuna, shrimp, and sea scallops–that’s always like a fun conversation starter. I talk with my parents about sustainable seafood options probably every month, and I’m not a kid that talks with my parents super frequently, so that’s a lot for us! I think it is reasonable to switch a lot of human consumption from meat to aquatic species that are a lot more sustainable and can potentially help areas of the world dependent on subsistence food sources.

I think disease ecology is not only one of the biggest problems for aquaculture as an emerging industry on the globe but is also one of the areas in ecology that we tend to overlook the most, not because anyone is dumb or forgetful or anything but because it’s just something that we haven’t traditionally prioritized. So translating my research into applicable solutions for aquaculture is something that I think about a lot, because I’m interested in becoming a better science communicator, and I’m always trying to think of ways that I can communicate concepts about disease ecology to high schoolers and younger children. The world of virology is niche enough that you can’t just start talking about viral genotypes. It’s a little bit too far out from primary school education to just launch into it. Most people don’t go to a fish farm. Most people don’t learn about viral evolution. I’m always trying to think of different ways that I can make my work relevant. Besides being interesting to me, it’s also integral to our global food system, which means it matters for everyone.

Come back next week for our second and final installment, where Malina will talk about being a science communicator and how she’s been engaging with changes that have been occurring in the marine sciences and academia in general since the COVID-19 pandemic and the resurgence of the Black Lives Matter movement last year.