FW 204 - Aging

scales pros

easily removed with minimal risk, traditional structure

scales cons

not all fish have scales, vary between location on body for different species, can be regenerated, must look at 5-10 scales per fish

rays, spines, bones, lenses pros

rays/spines can be removed without killing fish, less likely to be lost/regenerated, most fish have rays, spines, bones, or eye lenses

rays, spines, bones, lenses cons

bones/lens removal kills fish, may not have good agreement with scales, bony material may be resorbed

otolith pros

very fine resolution of growth, not resorbed, lost or regenerated

otolith cons

removal is always lethal