5 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 postdoctoral 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 parcticipate in doing some of this lab work and will report our findings 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.

On white spots on the two slides are the ototliths set in the resin. The resin comes packaged in that cylinder to the right; I had to chip off a piece a little larger than the otolith.