15 August, 1999

Aloha from UH- Manoa.

This is my last day in the lab. I will try to perfect

my technique in preparing the otoliths for examination

under the microscope so that I can look for the

incremental growth rings.

Dr. Radtke told me that we will actually be removing

the otoliths while we are in the lab at Thule and we

won't have to try to do this in the cold. while we

are at the lakes we will be mapping where we take the

fish, some physical parameters of the water, and take

measurements of the we catch in a specific size class

fish and keeping those that we will look at in the

lab.

to prepare the slides I use a resin compound that will

melt on a hot plate and then solidify again at room

temperature. It can be reheated any number of times

so that I can get the otolith completely covered by

the resin and oriented parallel to the surface. This

way the growth rings can be counted easily. The resin

is appears similar to the resin used on surf boards

for glassing. It is clear and is easily as it is

worked and reworked. when the otolith is set in the

resin, it is ground on a flat glass plate with very

fine sand paper (500-600 grit)so that the otolith is

exposed flush to the surface yet held by the resin

around it. this is tricky as you don't want to shave

it so far down that you damage the outer edge for

counting rings, yet you want to easily see the rings

with no resin distorting the view. Then the otolith

is polished with a felt wheel coated with an aluminum

grit solution. One I dropped and the tiny otolith

fell out of the resin mold. The other two, according

to my teacher, Dave Schafer, Dr. Radtke's post

doctoral student, were excellent.

After this preparation the otoliths are viewed with a

light microscope. The microscope has a video camera

hooked up to it that feeds the image into a computer.

The National Health Institute, NIH, makes a freeware

program that anyone can down load that takes the image

and allows it to be enhanced. This way you can count

the magnified image from the computer screen which is

easier.

This work will be done on the Greenland otoliths when

the research team returns to Hawaii. I will get to

parcticpate in doing some of this lab work and will

report our finding to you at that time.

Aloha again to my fellow travelers. Paul, Heather, and

Hans have been writing and asking for more pictures.

We have been experiencing some incompatability

problems and the bugs are being worked out. If you

return to my July Alaska journals you will now find

pictures. Please let me know if there is something

you would like to see and I will attempt to get a

picture.