successive measurements of growth annuli on an established trasect

Posted by Mark Schmitz on Oct 14, 2005; 4:34pm
URL: http://imagej.273.s1.nabble.com/successive-measurements-of-growth-annuli-on-an-established-trasect-tp3704667.html

I'm utilizing cross-sectioned dorsal fish spines to back-calculate length at age
of walleye.  Essentially I am looking for advice on how to measure the distance
between successive growth annuli (similar to growth rings on a tree).  I'm
attempting to 1) establish a transect from the origin (center) of the spine to
the outside edge followed by 2) along this transect, mark the intersection of
numerous, yet successive, growth rings which would allow me to 3) record the
relative distance between these points that would allow me to back-calculate
length at different known ages.  The key unknown issue is how to force these
points of measurement on an established transect w/o loosing that transect
after every measurement.  Any thoughts?

Mark Schmitz