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,
Lemon sole Lemon sole The lemon sole ("Microstomus kitt") is a flatfish of the family Pleuronectidae. It is native to shallow seas around Northern Europe, where it lives on stony bottoms down to depths of about . It grows up to in length and reaches about in weight. It is a popular food fish. The lemon sole is a right-eyed flatfish with a small head and mouth and smooth, slimy skin. The upper surface is reddish brown in colour, mottled with pink and orange and flecks of yellow and green, and a prominent orange patch is typically found behind the pectoral fin,