Aging Bony Fish

Robert LorenBy Robert Loren 5 years ago
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Pair of otoliths.

Pair of otoliths.

When conducting studies, many ecologists are posed with the question: How old is this fish? Because size is rarely a fair indication of age, the use of a more precise method is often required. The most prevalent method of aging bony fish is known as Otolith Analysis. This procedure entails the extraction and microscope analysis of the fish’s otoliths – small calcium carbonate structures that are located slightly posterior to the fish’s eyes. 
An otolith with visible annuli.

An otolith with visible annuli.

 These structures, which are used as gravity, balance, and movement indicators, grow continuously throughout a fish’s life and exhibit a unique growth pattern. This growth pattern is thought to be a result of seasonal temperature changes – during the winter, the otoliths grow slowly, accreting lightly-colored calcium carbonate; during the summer, the otoliths grow quickly, accreting darker calcium carbonate. The contrast between lighter calcium carbonate and darker calcium carbonate forms rings known as annuli. Since each annuli represents one year, scientists may determine the age of the fish by counting them.

Categories:
  Conservation, Fish, Science
Robert Loren
About

 Robert Loren

  (11 articles)

Robert, who comically refers to himself as a "budding biologist" is currently an undergraduate at Cornell University.

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