Taking a closer look at structures in the inner ear improves accuracy of age estimation in fish.

Prof. Satoshi Katayama (Lab. Fisheries biology and ecology) have identified four distinct zones in the otolith, a calcium carbonate structure in the inner ear, which can be used to determine age in fish.
S. Katayama: A description of four types of otolith opaque zone, Fisheries Science, 84, 735-745

This paper documented the structural and biological characteristics of the four distinct types of opaque zones. Many researchers on fisheries resources can utilize this knowledge, and determine the fish age easily and correctly. Multiple types of the annual structures of fish otolith were documented on the first time in the world.Using the information of this article, manual for the age determination of fish will be published.

This research were put out to the public via a news release by Tohoku University International Public Relation.
https://www.tohoku.ac.jp/en/press/determining_fish_age.html
https://www.alphagalileo.org/en-gb/Item-Display/ItemId/171862?returnurl=https://www.alphagalileo.org/en-gb/Item-Display/ItemId/171862
https://www.researchsea.com/html/article.php/aid/12267/cid/5/research//tohoku_university/determining_fish_age_using_inner_ear_structures_.html