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,
Pacific sanddab Pacific sanddab The Pacific sanddab ("Citharichthys sordidus") is a species of flatfish. It is by far the most common sanddab, and it shares its habitat with the longfin sanddab ("C. xanthostigma") and the speckled sanddab ("C. stigmaeus"). It is a medium-sized flatfish, with a light brown color mottled brown or black, occasionally with white or orange spots. The Pacific sanddab is endemic to the northern Pacific Ocean, from the Sea of Japan to the coast of California. They are most commonly found at depths of , though the young inhabit shallower waters, occasionally moving into tide pools. It is an