Fish as proxies of ecological and environmental change

Anthropogenic impacts have shifted aquatic ecosystems far from prehistoric baseline states; yet, understanding these impacts is impeded by a lack of available long-term data that realistically reflects the organisms and their habitats prior to human disturbance. Fish are excellent, and largely underused, proxies for elucidating the degree, direction and scale of shifts in aquatic ecosystems. This paper highlights potential sources of qualitative and quantitative data derived from contemporary, archived and ancient fish samples, and then, using key examples, discusses the types of long-term temporal information that can be obtained. This paper identifies future research needs with a focus on the Southern Hemisphere, as baseline shifts are poorly described relative to the Northern Hemisphere. Temporal data sourced from fish can improve our understanding of how aquatic ecosystems have changed, particularly when multiple sources of data are used, enhancing our ability to interpret the current state of aquatic ecosystems and establish effective measures to safeguard against further adverse shifts. The range of biological, ecological and environmental data obtained from fish can be integrated to better define ecosystem baseline states on which to establish policy goals for future conservation and exploitation practices.Christopher Izzo, Zoë A. Doubleday, Gretchen L. Grammer, Kayla L. Gilmore, Heidi K. Alleway, Thomas C. Barnes, Morgan C. F. Disspain, Ana Judith Giraldo, Nastaran Mazloumi, Bronwyn M. Gillander