Friday, July 19, 2002

Friday Word of the day: Otolith:  N Also called Earstones. A calcareous concretion in the inner ear of a fish. Rings on an otolith can be used to judge the age of a fish after the same fashion of counting the rings of a tree. The rate of growth of the fish for a given year of its life can also be calculated. Looking at old otoliths can give insight into the climate that the fish endured as environmental signals pop up in the data. For example, tightly packed rings (or annuli) indicate a series of very cold years. One of my coworkers studied historical fish growth data for upper and lower red lakes. The samples included Freshwater Drums or sheepshead caught in 1950 that were 73 years old at the time they were caught. So these otoliths give clues to what the environment was like back to the late 1800's. They were able to pick up the signal of an picked up an El Nino year this way. My other co-worker studied the otoliths recovered from indian village sites that were dated to the early part of the 1800s The data on those otoliths matched the data taken from tree trunks in the area. Slow growth in trees matched slow growth in the fish. 3:31:28 PM    comment []

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