Accurate quantitative descriptions of bull trout (Salvelinus confluentus) growth are important for understanding life history and developing reliable stock assessments. In the absence of age validation, important steps are to review the precision of age estimation methods and evaluate whether age estimates yield growth rates consistent with known fish growth based on tag recoveries. We assessed the precision of age estimates using pelvic fin rays and scales for migratory bull trout (297–605 mm total length) from the North Fork Clearwater River, and then compared growth estimates derived from both structures with growth based on tag recoveries. Fin rays produced a lower coefficient of variation (CV = 5.84) than scales (CV = 12.56). Ages estimated from scales were higher for fish aged < 5 with fin rays and lower for fish aged ≥ 5. Comparisons of growth estimates derived from 70 tagged bull trout at large from 0.35 to 3.02 years with age-length equations based on fin ray and scale annuli indicated that ages estimated from fin rays (N = 189, predicted length of an age 3 fish = 310mm) were closely related to the apparent ages estimated from the mark-recapture model (apparent age of a 310mm fish = 2.9) whereas scales (N = 65, predicted length of an age 3 fish = 408mm) were not. This is the first study to assess the precision of structures for modeling growth of larger migratory bull trout. However validation of annuli formation from the recapture of known-age fish is recommended.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 87 • No. 4