title: Using scale characteristics and water temperature to reconstruct growth rates of juvenile steelhead Oncorhynchus mykiss.
abstract: Juvenile steelhead Oncorhynchus mykiss from a northern California Central Valley population were reared in a controlled laboratory experiment. Significantly different rates of growth were observed among fish reared under two ration treatments and three temperature treatments (8, 14 and 20°C). Wider circulus spacing and faster deposition was associated with faster growth. For the same growth rate, however, circulus spacing was two-fold wider and deposited 36% less frequently in the cold compared to the hot temperature treatment. In a multiple linear regression, median circulus spacing and water temperature accounted for 68% of the variation in observed O. mykiss growth. These results corroborate previous research on scale characteristics and growth, while providing novel evidence that highlights the importance of water temperature in these relationships. Thus, this study establishes the utility of using scale analysis as a relatively non-invasive method for inferring growth in salmonids.
authors.affiliation: Earth to Ocean Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada; Center for Stock Assessment Research, Department of Applied Mathematics and Statistics, University of California-Santa Cruz, Santa Cruz, CA, 95064, U.S.A.
authors.forename: M P
authors.initials: MP
authors.lastname: Beakes
authors.forename: S
authors.initials: S
authors.lastname: Sharron
authors.forename: R
authors.initials: R
authors.lastname: Charish
authors.forename: J W
authors.initials: JW
authors.lastname: Moore
authors.forename: W H
authors.initials: WH
authors.lastname: Satterthwaite
authors.forename: E
authors.initials: E
authors.lastname: Sturm
authors.forename: B K
authors.initials: BK
authors.lastname: Wells
authors.forename: S M
authors.initials: SM
authors.lastname: Sogard
authors.forename: M
authors.initials: M
authors.lastname: Mangel
mesh_terms: D000818:Animals; D002140:California; D016014:Linear Models; D017686:Oncorhynchus mykiss / Q000033:anatomy & histology / Q000254:growth & development*; D013696:Temperature; D014867:Water
chemical_list: D014867:Water
keywords: circuli; life history; rainbow trout; salmonids; scale analysis