Quick Dips

Fish Stocks By Ear

Otoliths, or ear bones, taken from deep water fish are providing information on New Zealand's fisheries resource.

"Otoliths provide valuable clues on aging, growth and mortality," says Di Tracey of MAF Fisheries. "Seasonal differences in the growth of the fish or stressful events leave marks or rings in the otolith, similar to the rings in a tree trunk."

Information from the ear bones is collated with other biological details, such as the length, weight, sex and stomach contents to help build up a picture of fish stocks.

The work has been made simpler with the electronic weighing equipment and computerised data entry systems on board the new MAF research vessel, the Tangaroa.