Body Condition Correlates with Instantaneous Growth in Stream‐Dwelling Rainbow Trout and Arctic Grayling

• Published in: Transactions of the American Fisheries Society
• Main Authors: Bentley, Kale T., Schindler, Daniel E.
• Other Authors: National Science Foundation, Gordon and Betty Moore Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Arctic; Arctic grayling; Thymallus arcticus; Alaska
• Online Access: http://dx.doi.org/10.1080/00028487.2013.769899; https://onlinelibrary.wiley.com/doi/pdf/10.1080/00028487.2013.769899; https://onlinelibrary.wiley.com/doi/full-xml/10.1080/00028487.2013.769899; https://afspubs.onlinelibrary.wiley.com/doi/pdf/10.1080/00028487.2013.769899

Abstract Understanding the growth response of fish to varying environmental and biological conditions is important for the management and conservation of populations and communities. However, obtaining growth data at time scales shorter than those provided by annual size‐at‐age relationships is costly and labor intensive and can be logistically impractical. We assessed the ability of a body condition index to serve as a proxy for individual instantaneous growth rates in two species of mostly subadult stream‐dwelling salmonids in southwestern Alaska. We found that relative body condition, as measured by the residuals around a length–mass regression, was strongly correlated with direct measures of individual instantaneous growth (day −1 ) from mark–recapture data. Further, body condition was significantly correlated with growth accumulated over a period of roughly 2–10 weeks in both Rainbow Trout Oncorhynchus mykiss and Arctic Grayling Thymallus arcticus , while the relationship was typically weaker for time periods of less than 2 weeks and greater than 1 year. Despite the limitations of using body condition indices to infer the physiological status of individuals, our results demonstrate that, when applied judiciously, body condition can be used as a surrogate for recent individual instantaneous growth rate.