| Abstract: | We estimated long-term tag-shedding rates for lake trout Salvelinus namaycush using two existing models and a model we developed to account for the observed permanence of some tags. Because tag design changed over the course of the study, we examined the tag-shedding rates for three types of numbered anchor tags (Floy tags FD-67, FD-67C, and FD-68BC) and an unprinted anchor tag (FD-67F). Lake trout from the Gull Island Shoal region, Lake Superior, were double-tagged and subsequent recaptures were monitored in annual surveys conducted from 1974 to 1992. We modeled tag-shedding rates, using time at liberty and probabilities of tag shedding estimated from fish released in 1974 and 1978-1983 and later recaptured. Long-term shedding of numbered anchor tags in lake trout was best described by a nonlinear model with two parameters: an instantaneous tag-shedding rate and a constant representing the proportion of tags that were never shed. Although our estimates of annual shedding rates varied with tag type (0.300 for FD-67, 0.441 for FD-67C, and 0.656 for FD-68BC), differences were not significant. About 36% of tags remained permanently affixed to the fish. Of the numbered tags that were shed (about 64%), two mechanisms contributed to tag loss: disintegration and dislodgment. Tags from about 11% of recaptured fish had disintegrated, but most tags were dislodged. Unprinted tags were shed at a significant but low rate immediately after release, but the long-term annual shedding rate of these tags was only 0.013. Compared with unprinted tags, numbered tags dislodged at higher annual rates; we hypothesized that this was due to the greater frictional drag associated with the larger cross-sectional area of numbered tags. |
| Genre: | Article |
| ProdID: | 1000677 |
| Citation Author: | Fabrizio, Mary C.; Swanson, Bruce L.; Schram, Stephen T.; Hoff, Michael H. |
| Citation Contributing Office: | Great Lakes Science Center |
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| Citation End Page: | 273 |
| Citation Issue: | 2 |
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| Citation Language: | English |
| Citation Larger Work Title: | Transactions of the American Fisheries Society |
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| Citation Number Of Pages: | 12 |
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| Citation Phsyical Description: | p. 261-273 |
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| Citation Search Results Text: | Comparison of three nonlinear models to describe long-term tag shedding by lake trout; 1996; Article; Journal; Transactions of the American Fisheries Society; Fabrizio, Mary C.; Swanson, Bruce L.; Schram, Stephen T.; Hoff, Michael H. |
| Citation Start Page: | 261 |
| Citation Volume: | 125 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Comparison of three nonlinear models to describe long-term tag shedding by lake trout; 1996; Article; Journal; Transactions of the American Fisheries Society; Fabrizio, Mary C.; Swanson, Bruce L.; Schram, Stephen T.; Hoff, Michael H. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
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