Fish have always lived in changing environments, but the pace and combination of changes they now face are increasing. Warmer water, declining oxygen, shifting food availability and fishing mortality can occur together, with each challenge changing how the body works and how much capacity remains to deal with the next one. The difficulty is that the consequences of these pressures often become clear only after a fish population has declined, by which point we still do not understand the physiological processes that made it vulnerable in the first place. Dr Harriet Goodrich is an ecophysiologist whose research asks how fish function under change, and what that tells us about how they will cope with it.
Dr Goodrich and her group use experimental biology to trace the signatures that environmental change can leave behind in fish. These signatures can be found in their metabolism, behaviour, blood, guts, tissues and genes. Some are long lasting, such as those we might see in a population that has been heavily fished for decades, while others are short lived, such as those in the blood of a fish that has just been caught and released. Many are remarkably plastic, shifting from one individual to the next, between species, over time, and across regions, so that the same pressure can leave quite different marks depending on the fish it acts on. Reading and interpreting these signatures of change allows us to understand not only whether a fish has been affected by a stressor, but what has changed inside the animal, whether it will stay there, and whether it can recover. Scaled up from the individual to the population, that understanding becomes the kind of information managers need to make decisions across fisheries, aquaculture and conservation.
Most recently, her work on sand flathead in lutruwita, Tasmania, has revealed striking differences among fish from different parts of the state. Depending on where a sand flathead originates, we can predict how it will grow, use energy and respond to warming, and those differences persist even when fish are held under exactly the same conditions, or transplanted into opposing ones. She is now investigating what has caused this divergence and how persistent it might be, including whether long-term pressures such as fishing have left a lasting mark on how sand flathead function, and whether that history shapes their ability to cope with marine heatwaves and the other challenges ahead.