Mass-marking of otoliths of lake trout sac fry by temperature manipulation
American Fisheries Society Symposium
By: Roger A. Bergstedt, Randy L. Eshenroder, Charles Bowen, James G. Seelye, and Jeffrey C. Locke
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Abstract
The otoliths of 676,000 sac fry of lake trout Salvelinus namaycush in 1986, and of 1,100,000 in 1987, were marked by daily manipulation of water temperature. The fish were stocked into Lake Huron in the spring. Otolith marks consisted of groups of daily growth rings accentuated into recognizable patterns by steadily raising and lowering the temperature about 10 degrees C (from a base of 1-4 degrees C) over 14 h. In 1987, groups of marked and control fish were held for 6 months. The otoliths were removed from samples of the fish, embedded in epoxy, thin sectioned by grinding in the sagittal plane, etched, and viewed by using a combination of a compound microscope (400-1000x) and a video enhancement system. One or more readable otolith sections were obtained from 39 of a sample of 40 fish. Three independent readers examined 41 otoliths for marks and correctly classified the otoliths, with accuracies of 85, 98, and 100%, as being from marked or unmarked fish. The exact number of rings in a recognizable pattern sometimes differed from the number of temperature cycles to which the fish were exposed. Counts of daily rings within groups of six rings varied less than counts within groups of rings.
Suggested Citation
Bergstedt, R.A., Eshenroder, R., Bowen, C., Seelye, J.G., and Locke, J.C., 1990, Mass-marking of otoliths of lake trout sac fry by temperature manipulation: American Fisheries Society Symposium, v. 7, p. 216-223.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Mass-marking of otoliths of lake trout sac fry by temperature manipulation |
| Series title | American Fisheries Society Symposium |
| Volume | 7 |
| Year Published | 1990 |
| Language | English |
| Contributing office(s) | Great Lakes Science Center |
| Description | p. 216-223 |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | American Fisheries Society Symposium |
| First page | 216 |
| Last page | 223 |