Saltwater sleuths: Seeking clues to help determine the ages of fish and shellfish p...(e conducted with Canadian colleagues. Re...)

Age reading has an official name sclerochronology, defined as the study of periodic increments in skeletal organisms like shells, scales, otoliths and vertebra. While it is not as well known to the public as dendochronology, the study of tree rings used to determine age and environmental changes, sclerochronology has become an increasingly important tool in the marine sciences.

Sclerochronology can reconstruct the life history and environmental conditions preserved in fossil skeletons, such as the daily banding in coral reef skeletons and the annual growth rings in mollusk shells. Growth patterns can reflect monthly, fortnightly (every two weeks), tidal and even daily increments of time. The first known reliable age estimate of a fish occurred in 1759, but it was not until the end of the 19th century that the art of age estimation was rediscovered.

Burnett says the aging program began at the NEFSC in the 1940s with haddock and yellowtail flounder scales but really picked up steam in the 1960s. Today the group is among the most active in the nation, providing age data for stock assessments not just for the NEFSC but also for the Commonwealth of Massachusetts and several other states as well as for Canadas Department of Fisheries and Oceans, since some stocks straddle political boundaries. Other U.S. environmental agencies, such as the EPA, and academic scientists seek the expertise of this group as well, or seek access to the several decades worth of archived samples.

The responsibilities for age samples and data, and the declining number of organizations who have age readers, keep the group busy. Each winter, sam
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