Age determination and scale archive

Age determination methods are being developed to improve the accuracy of the results. This includes the wider use of calcified structures in research. In particular, the use of otoliths, i.e. the earstones of fish, is becoming more common in age determination. Staining the otolith cross section makes it possible to distinguish annuli as clear dark stripes.

Goals of the programme

As a part of this programme, age determination of fish is made more efficient and reliable. The existing scale material will be examined and then stored in a scale archive for future use. The material can be used in DNA analyses and growth comparisons, for example. Older scale data collected e.g. from unbuilt river systems in natural state can be compared with current material.

Results

- Age determination from stained otoliths has improved the information collected on Baltic herring (Clupea harengus membras) stocks.

- Marking the fry with alizarin red and interpreting marked otoliths are now routine methods.

- Archiving and saving of scale, bone and otolith material collected since 1945 is continuing.

- For age determination in Baltic herring, stained otolith slices are now used instead of whole otoliths.

Scientist in charge of project

Jari Raitaniemi
Finnish Game and Fisheries Research Institute
Turku Game and Fisheries Research
Itäinen Pitkäkatu 3, 20520 Turku, Finland
Tel. +358 - (0)205 751 685, fax +358 - (0)205 751 689
e-mail: firstname.lastname@rktl.fi

Other research staff: Tarja Wiik, Teuvo Niva, Rauno Hokki

Duration: continuous

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