Otolittreferansesamling for lodde (Mallotus villosus) i Barentshavet

Abstract

In 2007 a project was initiated at the Institute of Marine Research, Bergen, with the aim to further develop the methods for age determination of fish by their otoliths, as well as to assure the quality of routine age determination work. One of the goals in that project was to develop a reference collection for each species. These collections would be used as a guide for new age readers, but also for checking the precision of the routine age reading. Bente Røttingen and Jaime Alvarez started to plan a reference collection of capelin otoliths in 2008, and selected otoliths from 1981, when the historic material contained otoliths from all months throughout the year. The otoliths were selected based on the criterion that they should be easy to interpret. Since the age reading of capelin by yearly rings in the otoliths never have been validated, the age given is agreed age by experienced readers. It is concluded that even with the equipment available at present, interpretation of digital pictures cannot replace the direct reading through the binocular. However, the reference collection is a valuable tool for establishing a standard for how capelin otoliths are presently interpreted at the Institute of Marine Research.