BOSTON—Chesapeake Bay oysters that lived a half a million years ago were on average 1.5 times bigger than the oysters in the bay today, researchers reported here yesterday at the annual meeting of AAAS, which publishes Science. These ancient oysters also lived about four times as long as their modern relatives. That’s according to alternating white and gray bands on the hinges of fossil shells, which function a bit like tree rings. (The shell pictured here is an extreme example from 28 million years ago and was not used in this study.) The findings suggest that today’s oysters are fished before they grow up. Oysters start out male and then become female as they age, and larger females are more reproductively active. By harvesting oysters too soon, we are inadvertently removing the female oysters that are more likely to produce a lot of offspring. These results suggest that long-term sanctuaries that protect the larger female oysters could help increase the Chesapeake Bay population.
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