May 2025
What we thought was a typical day in Ms. Handa's AP Environmental Studies class took an unexpected turn as we observed the salmon for the first time in our classroom tank. We had learned that just four years prior, researchers observed salmon in tanks and noticed erratic behavior such as swimming in different directions, spinning, and displaying corkscrew swim patterns. Within a few days, some of those young Chinook salmon were reported dead, and during the next two weeks their mysterious behavior seemed impossible to figure out, until they added vitamin B1 (thiamine) to their water and the fish started to behave normally again. This left the researchers at the California Department of Fish and Wildlife’s Fish Health Laboratory, US Fish and Wildlife Service, and University of California (UC) Davis Aquatic Animal Health Laboratory with a puzzling question—how did this thiamine deficiency happen?
Researchers from UC Davis, and NOAA Fisheries formed the Thiamine Deficiency Complex (TDC) research team and invited experts from many disciplines (microbial biologists, veterinarians, oceanographers) and geographies (Great Lakes, Oregon, Washington, Canada, Alaska), with a goal of observing the salmon affected by this disease in the Western United States. Since the science team does not have enough data to test their hypotheses about the physiological impacts of TDC on California salmon and survival rates, local Central Valley schools have stepped up to provide qualitative and quantitative data for statistical analysis regarding juvenile Chinook salmon survival and behavior.
Why Involve Students in this Research?
Through a grant from NOAA to the Solano County Office of Education, supported by the California Bay Watershed Education and Training (B-WET) program, the Spinning Salmon Program allows high school students from Central Valley, like us, to help scientists and get hands-on experience with solving environmental problems and to help to fill data gaps that universities like UC Davis or UC Santa Cruz’s research may not be able to fill. The California B-WET program provides opportunities for students to engage in meaningful outdoor experiences that connect students to their surrounding environment and special places like national marine sanctuaries.
According to Peggy Harte, the Youth Education Program Manager for UC Davis’ Center for Community and Citizen Science, the Spinning Salmon Program is all about helping students see themselves as contributing to science. “When they realize that the data they’re collecting contributes to real NOAA research and helps address local environmental issues, it transforms the way they think about learning—and about their own ability to take action and make change,” explains Harte. “They're not just studying science, they’re doing science, and that opens doors to future careers and lifelong curiosity."
Researchers study TDC in adult Chinook, steelhead, and Coho salmon by taking egg samples to test for the prevalence of TDC, and tissue samples to reconstruct the food web and understand the cause of TDC. The EC50 curve, also called a “dose-response curve,” is common in toxicology studies and here is used to plot the effect of low thiamine on the survival of juveniles. Our classroom was responsible for providing the survival data and behavioral observations of the Chinook salmon from the time they were eggs until they became fry and were ready for release. We were in charge to record any deaths and irregular behaviors observed and provide the data to help scientists understand the severity of the TDC to hopefully uncover an effective solution to address this challenge.
Along with our friends and classmates, we have not only contributed to the research but we now also understand the importance of educating future generations about human impacts on salmon and their ecosystem. This knowledge can motivate people to take the initiative to steward and safeguard our ocean.
Although the concept of the TDC has been studied in California for five years, scientists are still studying the full extent of its impact on aquatic ecosystems. We had the opportunity to do our investigation and examine the behavior of a representative sample of thousands of salmon eggs of a project that started in 2020. We conduct observations weekly and look for any connections between the thiamine levels in female salmon and notable effects on their offspring (juvenile salmon) to make a hypothesis of the thiamine level of salmon in our tank.
Several teachers shared their experience of having their classrooms participate in the Spinning Salmon Program, like Samantha Bright (part of the GEAR UP College Opportunity Program collaboration), who says, “We can run experiments in class that simulate what it is like to be a scientist, but for this [project] they [the students] really were scientists. It gave the students a higher sense of purpose. With highschoolers, who mostly focus on themselves and the narrower world they live in, getting a chance to engage them in something bigger than them is huge!”
What is TDC?
TDC stands for thiamine deficiency complex. Thiamine is an organic compound known as vitamin B1 that naturally supports nerve, muscle, and heart function. This micronutrient is essential for animals and humans to survive, as it helps them convert food into energy for growth and development, cellular function, and bolstering immune system strength, thus, protecting them from diseases. A lack of this micronutrient is called TDC, and unfortunately, it has affected reproduction in salmon populations.
Chinook salmon are anadromous species that play a major role in the local ecosystem. They are born in freshwater, then migrate to the ocean, and later go back to the freshwaters where they were born to reproduce. After reproduction, their life cycle ends and their decaying bodies provide nitrogen and phosphorus that help rivers and forests grow. According to NOAA Fisheries, “the production and survival of juvenile winter-run Chinook salmon in the Sacramento River in 2022 was the lowest on record.” The lower reproductive rates are attributed to decreased thiamine levels in adults, which reduced the survival of their offspring, as well as other factors that haven’t yet been identified.
What Has Caused TDC in the Salmon Population?
Originally, the diet of the Chinook salmon was composed of a diverse group of species like sardines, krill, squid, flatfish, lingcod and hake. However the diet has changed due to a boom in northern anchovy populations and a scarcity of other typical salmon prey— leading anchovy to become this salmon population’s main source of food.
Thiaminase is an enzyme that breaks down thiamine, and it is produced by organisms, such as anchovies, which are a favorite food of Chinook salmon. The boom observed in the northern anchovy population from 2018 to 2020, along with studies that observed the same trend of TDC found in other fishes, particularly other anchovy predators, led researchers to connect the dots—attributing the anchovy-rich diet of the salmon as the main cause of TDC. Basically, the Chinook salmon that preyed heavily on the anchovies while in the ocean returned to Central Valley rivers and streams with low thiamine concentrations in their eggs. The concentrations were so low that it led many of their offspring to develop TDC.
Over the past five years of research in classrooms and facilities, Chinook eggs have shown to be critically thiamine deficient, causing the offspring to exhibit strange spinning behaviors and high mortality rates. To find a solution for this, investigators have started to experiment by providing young salmon with a “bath” of thiamine. This is a process where eggs are placed in thiamine-boosted water at fertilization to compensate for their deficiency and help the developing embryos.
Our Experience with the Spinning Salmon Program
Our experience with the Spinning Salmon Program has been both fascinating and enlightening. Prior to this program, we had little knowledge of what thiamine was and its role in the function of living organisms. The intricacy of what salmon are currently going through has extended far beyond what we previously understood. With the guidance of professionals taking part in this program, who we had the pleasure of speaking to in person, we experienced what it’s like to ponder like a scientist, record data, ask questions, and acquire knowledge about a topic we were unfamiliar with. It also allowed us to assist in the discovery of a potential solution to help salmon combat their reproductive challenges.
Observing the newly hatched salmon undergo the beginning stages of their life cycle in real time and releasing them at the Sacramento River was a touching experience. It compelled us to feel compassion and create a bond with these extraordinary creatures who play a vital role in our ecosystem. We gained an understanding of the key factor disrupting the salmon's development: thiaminase. This enzyme causes nutrient deficiencies which results in behavioral issues among the fish. Through examinations of their habits in a tank established in our classroom and teachings about the possible causes of the TDC in salmon, we had the opportunity to view and recognize the effects of these stressors, firsthand.
Overall, our involvement in this program provided us with many new insights. It enhanced our abilities to collect data and expanded our knowledge of the complexity of marine ecosystems and how disruptions to natural cycles can negatively impact the ecosystem's health and resilience. The Spinning Salmon Program not only serves as a learning experience, but also helps institute a new generation that cares about improving the quality of life of all living organisms. Discovering the long-lasting harm that is occurring to salmon populations has inspired us to be part of the efforts to conserve the health of our ecosystems for future generations.
The authors of this article are the students from Fairfield High School’s AP environmental studies classroom who are participating in the Spinning Salmon Program under the guidance of their teacher, Ms. Heather Handa and UC Davis Center for Community and Citizen Science Youth Education Program Manager, Peggy Harte
Rachel Plunkett is the content manager and senior writer/editor for NOAA’s Office of National Marine Sanctuaries