| Autor: |
Scarnecchia, DennisL., Ryckman, L.Fred, Lim, Youngtaik, Power, Greg, Schmitz, Brad, Riggs, Vic |
| Zdroj: |
Transactions of the American Fisheries Society; July 2006, Vol. 135 Issue: 4 p1086-1094, 9p |
| Abstrakt: |
AbstractAn approach is described to assess the accuracy and precision of age estimates for paddlefish Polyodon spathulaof the Yellowstone–Sakakawea stock in Montana and North Dakota. Twenty-five of 30 fish tagged with coded wire tags as age-0 fish in 1995 and recaptured over the period 2002–2005 were independently aged correctly with dentaries (lower jaw bones); estimates for the other five fish deviated from actual ages by 1 year. For fish older than age 10, estimated ages based on dentaries collected from 1991 to 2004 were compared with the estimated minimum expected ages of recovered fish that were jaw-tagged during 1964–2004. Of 323 fish, 300 (93%) had estimated ages that were the minimum expected age or older. The ages for the remaining 23 fish were less than the minimum expected ages, mostly by three or fewer years; these fish spanned a range of ages but tended to be older. Precision estimates (mean coefficient of variation) for age determination ranged from 3.6% for female fish from Montana in 2003 to 7.1% for male fish from North Dakota in 2003. The results indicate that estimating ages from Yellowstone–Sakakawea paddlefish dentaries is generally a repeatable, straightforward process with sufficient accuracy and precision to be useful for stock assessment. Validation studies should be conducted on other paddlefish stocks because the ease of interpreting dentaries varies with locality. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Plný text