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Generalized Otolith Dissection

There are several ways to dissect otoliths from fish. Project considerations or fish type will direct the most appropriate method:

Are you collecting sagittae, lapillae, and asteriscae? - see Figure 1.
Do you need to collect a pure sample of brain tissue as well? - see Figure 2.
Just collecting sagittae? - see Figure 3.
Is it a hard-headed fish? - see Figure 4, 5, 6, and 7.


Generalized Disection Figure 1

Figure 1. To access all otoliths from a fish, a cut bisecting the cranium dorso-ventrally will splay halves open to see symmetrical location of lapillae, asteriscae, and sagittae otoliths.


Generalized

Figure 2. Collecting uncontaminated brain tissue in addition to sagittae otoliths, requires a cut allowing removal of the brain tissue first. Sagittal otoliths are then removed by angling forceps to the ventral posterior of the cranium, pulling otoliths from the sagittal wells.


Generalized Disection Figure 3

Figure 3. Basic cut to remove sagittae otoliths from most fish.


Generalized Disection Figure 4

Figure 4. Otoliths of rockfish are removed from the bottom of the cranium, accessed through the gill.


Generalized Disection Figure 5

Figure 5. Sever the gill at its dorsal insertion point.


Generalized Disection Figure 6

Figure 6. Posterior of the pseudobranch, scrape away tissue overlying a translucenct area of the bottom of the cranium(seen at tip of forceps). Behind this translucent spot will be one sagittae otolith.


Generalized Disection Figure 7

Figure 7. The translucent area chips easily with the point of a knife. Enlarge a hole through which the otolith may be removed.

Alaska Department of Fish and Game
P.O. Box 115526
1255 W. 8th Street
Juneau, AK 99811-5526
Phone: 907-465-4100
Fax: 907-465-2332
TTY: 800-478-3648
or 907-465-3646