Revealed: The simple ear check that reveals a fish’s sex life

Scientists have discovered a new method for examining sex lives and migration patterns of fish - by looking in their ears. By studying ear stones in fish, which act as tiny data recorders, scientists can now reveal what areas of the oceans the fish have been visiting and insights into their sexual behaviour. Tiny ear stones called otoliths, which are in all bony fish, store chemical elements picked up from the surrounding water.

These otoliths can now be used like the Rosetta Stone - allowing us to read the story of fish migrations from the chemistry of their ears.

Clive Trueman, co-author of the study

As fish migrate, changes in the ambient water chemistry are recorded in the otoliths, but it is difficult to translate these signals into records of fish movements. Now researchers say they have created a translation dictionary revealing what the different chemical elements stored in the chemical makeup of the stones can tell us about the environments fish have travelled through.

We found that sex can interfere with the chemical signals. This complicates the job of translation, but provides us with new information about the biology, and private lives, of fish at sea.

Clive Trueman

Science