3 August, 1999
Aloha from UH (The University of Hawaii--Manoa), It has been a quiet, yet busy day. I spent the latter part of the morning looking for a salmon fish head. I went first to my local grocery store. They had heads for only $.25 that were almost as large as my own; they were ahi, which is Hawaiian for yellow fin tuna. Finally I found a salmon head that was reasonable is size. This time I took photos and drew pictures to help me memorize the location of the otoliths. Happily I found all three this time, but because the head had been frozen; the smaller structures had recrystallized into another form of calcium carbonate distorting the shape somewhat. Aragonite is one form and Calcite is the second.
I then spent part of my day reading some journals that Dr. Radke had written on some of the research he has already done on charr. I believe I mentioned that rings grow on the otoliths, much like the rings of tree. It is believed that these rings are deposited daily. The experiment they performed was to rear charr for a set time period under different temperature and feeding regimes to see if the incrementation of the rings occurred daily. They found that at 7 degrees Centigrade and daily feeding this was true, but if the temperature was lowered to 1 or 3 degrees Centigrade or the food supply was limited the incrementation would fluctuate.
I asked Dr. Radke about the spawning habits of the charr. He said they are different from salmon in that they do not necessarily go to saltwater as juveniles and they do not return to the freshwater to die after spawning. Some fish remain in the freshwater and some may or may not migrate on a year to year basis to the saltwater for the better food supply in the summer months. If they do migrate, they will return to freshwater when the temperature drops to 0 centigrade because unlike most arctic fish they do not have antifreeze in their blood. They will winter over in lakes where the water will not freeze to the bottom. The final part of my day I spent preparing two glass microscope slides with a small slice of cardboard sandwiched between them. Holding it firmly together is a metal frame. The cardboard will have holes punched out which will contain the otoliths that we collect.
Contact the TEA in the field at .
If you cannot connect through your browser, copy the TEA's e-mail address in the "To:" line of your favorite e-mail package.