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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.
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.
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.
Figure 3. Basic cut to remove sagittae otoliths from most fish.
Figure 4. Otoliths of rockfish are removed from the bottom of the cranium, accessed through the gill.
Figure 5. Sever the gill at its dorsal insertion point.
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.
Figure 7. The translucent area chips easily with the point of a knife. Enlarge a hole through which the otolith may be removed.
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