Age determination in fish fish. Johannes Reibisch, working for the Commission of Scientific Investigation of German Seas at Kiel, attempted to use Hoffbauer’s techniques to age plaice ("Plueronectes platessa") but found it difficult to accurately discern annuli. He decided to study a different structure and in 1899 he published the first procedures using otoliths as an aging structure. A fellow scientist also with the German Commission at Kiel, Friedriche Heincke, also frustrated with difficult scale annuli, further studied other structures to age fish. He discovered annuli in the vertebrae, opercula, and pectoral girdle and published his findings in Heicke 1905. The works of Hoffbauer,
Common sole Common sole The common sole, Dover sole, or black sole ("Solea solea") is a species of flatfish in the family Soleidae. It lives on the sandy or muddy seabed of the northern Atlantic and the Mediterranean Sea where it often semi-immerses itself in the substrate. The upper side is greyish-brown while the underside is white. It grows to a maximum length of about . The species is prized as a food fish, being caught mostly by trawling on the seabed. The small eyes are close to each other on the right side of the body. This gives the fish the