PhD Scholar Leteisha Prescott recently returned home from her internship in Finland with Professor Katja Anttila’s laboratory at the University of Turku. On behalf of the Blue Economy CRC we congratulate Leteisha on the completion and approval of her thesis. We hope you enjoy reading about Leteisha’s journey and research.
As humans, we know regular exercise is key to a strong, healthy heart, but why not also for farmed fish? We hypothesise that exercise training could be a missing tool industry needs to improve the cardiac performance of farmed fish and possibly, at the same time, improve their thermal performance. In the final months of my PhD candidature, with the support of the Blue Economy CRC, Company of Biologists, Australia New Zealand Marine Biotechnology Society, and the Finnish National Agency for Education, I joined Professor Katja Anttila’s laboratory at the University of Turku to test this hypothesis and to investigate the mechanisms of exercise training on the cardiac performance of fish.
Rapidly changing environments, particularly warming waters and marine heatwaves are severely impacting the aquaculture sector. Farmed fish are unable to relocate or escape these warming waters and when sea temperatures surpass their upper thermal tolerance, physiological processes begin to fail. Summer mortality events triggered from increasing ocean temperatures are now often reported by farmers. Adaptive measures are needed to improve thermal resilience of farmed fish to avoid these ongoing scenarios, enable high animal welfare, and safeguard the production of high-quality protein foods for human consumption.
The fish heart is recognised as a thermally limiting organ when exposed to warming waters, and through domestication and selective breeding, heart health has declined. By providing farmed fish with more natural settings, such as moving water to swim against, cardiovascular performance can improve. Previous research has shown that exercise training increases cardiac muscle growth, maximum cardiac output, stroke volume, heart rate, and maximum cardiac power output of fish, and more recently, a study led by Professor Katja Anttila, showed moderate exercise training in farmed rainbow trout to improve cardiac thermal performance. We want to further explore if these improvements translate to a whole-animal levels and shed light on the tissue and cellular modifications leading to thermal-resilience.
At the end of August 2024, myself, Katja, and her PhD student, Thuy Le, loaded an entire lab into two cars and drove from Turku to Eastern Finland to test our hypothesis. For the experiments, we had two groups of rainbow trout; one under normal farm conditions and the other under an exercise training program. The training program involved trout swimming at one body length per second for six hours each day with weekends allocated for rest. The training program lasted four weeks. We also had physiologists Andreas Ekström and Jaakko Haverinen joining the team, and a series of physiological assessments planned: Star Oddi biologgers measuring heart rate and accelerometery during rearing and a critical thermal tolerance test; high resolution respirometry measuring cardiac mitochondrial function at two temperatures; cardiac flow probes and electrograms measuring heart function with declining oxygen exposure at two temperatures. The productive days of testing our exercise-enhanced thermal resilience hypothesis didn’t end at the hatchery, but rather following an intensive heat session in the sauna, reprieved by swims in a beautiful Finnish lake. Indeed, we were living our best Finnish life.
Back to Turku, we had a bunch of data analysis and tissues to process. Piecing all our findings together, we are positive exercise training is a new, viable, and immediately implementable tool that industry can use to equip their stocks with the necessary requirements to thrive in warming waters. Our research has provided key insights into the underlying mechanisms behind cardiovascular failure during warmer waters in fish that will contribute to an extremely active and important research field in fish physiology.
The three months spent integrated in Katja’s laboratory was extremely inspiring and enjoyable. Exposure to the Finnish trout industry, expanding my scientific community, and adding new skills to my toolbelt are only some of the invaluable opportunities and experiences I gained. After returning home, I am now extremely excited to share these new research findings with our local, the New Zealand’s and Australia’s salmon aquaculture industries, and to develop new projects to continue exploring the benefits of exercise training for robust and resilient finfish.
Read more about Leteisha’s research and PhD journey with the Blue Economy CRC.
