Standing ovations and professional representation when researchers from SLU Aqua participated in the Otolit Symposium in Chile in October

Allen Andrews, Michelle von Ehr, Yvette Heimbrand, Anneli Hilvarsson, Marju Kaljuste, Karin Limburg, Jennie Strömquist and Rickard Yngwe - all from SLU Aqua were present. Together, the SLU Aqua team contributed with 6 oral presentations and 6 posters. 

Karin Limburg and Yvette Heimbrand co-organized a workshop about chemical tracers in otoliths and other structures and Annelie Hilvarsson about ICES SmartDots. Yvette and Karin also had the “honor” of each being listed in the program booklet 17 times, more than anyone else. Yvette's research, which shows that otolithic chemical age determination on cod from the Baltic Sea is possible even when the growth rings on the otoliths are unclear and difficult to interpret, was something that was a highlight during one of the keynote talks. There was also a standing ovation for one of the researchers. You can read more about that a little further down. First, let's take this opportunity to learn more about otoliths.

The importance of otoliths

Information about the age structure of a fish population is very important in stock assessment. In the head of the fish there are small calcareous structures called otoliths (literally "ear stones") and as the fish grows, growth zones are formed in the otolith, which are used to estimate the age and growth rate of the fish. Thirty years ago, fisheries scientists came together to discuss how otoliths could improve stock assessment models.  And although this is still of fundamental importance, the field has expanded in many directions and involves multiple disciplines.

Otoliths consist primarily of crystals of calcium carbonate in a delicate network of proteins, and scientists have discovered that the formation of these biominerals is very complex. This complexity gives us insight into many processes that take place during a fish's lifetime. For example, we can track migratory behavior, tell something about salinities that a fish experiences, estimate its thermal history, and even understand whether it spent time in a low-oxygen “dead zone”. Furthermore, new research is exploring how otoliths reveal the metabolic status of fish, and how that relates to the stressors brought about by climate change. Most of these insights are accompanied by the “time-stamp” of annual age increments, so that we can know exactly what year of life – and often the calendar year – that something occurred.

Otolit chemistry has rekindled the interest of researchers

There’s also been a re-kindling of interest in chemistry that relates to the physiology of fish, whether it is metabolism as above, or reproductive status, or health impacts of parasites, to name a few examples. And not only do these insights, both environmental and physiological, tell us about the fish, but they also reflect onto the environmental conditions.  It’s then possible to build up a big picture of phenomena experienced by fishes, and by examining the tracers and the growth rings, say something about how fishes are faring in environmental change.

We are getting closer to a better understanding of the "secret life of fish"

The science of otoliths continues to evolve. With each new discovery, we come closer to understanding so many aspects of “the secret lives of fishes.” Not only can we say things about the present, but archaeological samples inform us about the past and what we learn can also help us to understand the likely future impacts of climate change.

Standing ovation when Karin Limburg received the Distinguished Career Award

Another highlight of the Otolith Symposium in Chile was when Karin Limburg received the Distinguished career award for her notable contribution to otolith science. Karin was celebrated with a standing ovation from the entire audience.