Otolith Microchemistry

Otolith MicrochemistryThe Association has, for a number of years, been collection the heads of bluefin tuna that are harvested during their commercial activities. The heads are provided to the Department of Fisheries and Oceans, Science Branch, where the ear bone or otoliths is retrieved for analysis.


Otoliths are calcium carbonate balance organs found in the inner ear of bony fishes. They are continuously deposited through the lifecycle of a fish, so studies can determine age and growth information. Otoliths also carry certain trace elements that are in proportion to water chemistry, allowing researchers to determine their water locations.

Otolith MicrochemistryStudies of otolith microchemistry reveal the origin of birth of fish caught in Canadian fisheries, and allow scientists to assess the extent of mixing between eastern and western bluefin stocks. Results to date indicate that Canadian fisheries almost exclusively rely upon bluefin tuna that were born in the Gulf of Mexico.