A Note On The Accuracy Of The Scale Method In Determining The Ages Of Largemouth Bass And Bluegill From Alabama Waters

Photographic prints were made of scales taken from largemouth bass (Micropterus salmoides Lacepede) and bluegill (Lepomis macrochirus Rafinesque) of known ages by the use of a micro-projection machine. The image of each scale was projected directly upon photographic paper to produce, upon development, a permanent negative print. In an examination of the prints of 272 largemouth bass scales, 80.1 percent were aged correctly when the ages were unknown to the technician. When the scales first aged incorrectly were re-examined after the technician knew the actual ages, an additional 3.7 percent was found to have the correct number of annuli although many were indistinct. A total of 16.2 percent of the bass scales did not possess annuli corresponding to the known ages. In an examination of 264 prints of the scales of bluegill, 76.1 percent were aged correctly when the ages were unknown. When the scales first aged incorrectly were re-examined after the technician knew the actual ages, an additional 4.9 percent was found to have the correct number of annuli; however, many were not distinct. Of the total number of bluegill scales studied, 18.9 percent did not possess annuli corresponding to the known ages.

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