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,
American smooth flounder American smooth flounder The American smooth flounder ("Pleuronectes putnami") is a flatfish of the family Pleuronectidae. It is a demersal fish that inhabits shallow inshore salt and brackish waters at depths of up to . Its native habitat is the temperate waters of the northwestern Atlantic, from Ungava Bay in Quebec, Canada to Rhode Island, United States. It can grow up to in length. The American smooth flounder is a right-eyed flatfish, resembling the winter flounder in shape and appearance. Its upper side, including the fins, ranges in colour from dark grey to brown or almost black, and may be