An automated marking trailer and a hand (manual) marking trailer were used to mark and coded-wire tag the brood year 2005 spring Chinook salmon at Warm Springs NFH during May of 2006. In a controlled side by side evaluation of fish marked in the two trailer types, fish were sampled during an early, middle, and late evaluation period. A total of 300 manually marked fish and 296 automated marked fish were visually examined for the presence of injuries and fin clip quality. Injury rates of fish did not differ between trailer types, with overall injury rates ranging between 4% and 13%. None of the injuries were considered to be life-threatening. Clip quality differed between fish marked in the automated trailer and fish marked in the manual trailer, with 5% of manually marked fish having no clip compared to less than 1% for automated marked fish. Manually marked fish also had a higher rate of partially clipped fins. Tag retention rates for automated marked fish averaged over 97%, while manually marked fish had an average tag retention rate of 87%. No difference in the average marking to release mortality rate were observed, although manually marked fish experienced a higher variability in mortality among raceways. Release to adult survival information will be monitored in the future to evaluate any differences between the two trailer types. Overall, the automated fish marking trailer had higher clip quality and tag retention with no increase in injury rates or marking to release survival when compared to the manual marking trailer. The results of this study should not be the sole determinant of whether to use an automated or manual trailer. Availability of trailers and markers, costs, mark type, hatchery goals, disease concerns, employment opportunities, and many other factors should also be considered by hatchery managers when deciding on a marking and tagging program at their hatchery.
Comparative Tag Retention, Clip Quality, and Injuries of Juvenile Spring Chinook Salmon Marked by an Automated Marking Trailer and Manual Marking Trailer at Warm Springs NFH
2007
21 pages
Report
Keine Angabe
Englisch