Otolith biochronologies as multidecadal indicators of body size anomalies in yellowfin sole (Limanda aspera)

Dendrochronology (tree-ring analysis) techniques have been increasingly applied to generate biochronologies from the otolith growth-increment widths of marine and freshwater fish species. These time series strongly relate to instrumental climate records and are presumed to reflect interannual variability in mean fish condition or size. However, the relationship of these otolith chronologies to fish somatic growth has not been well described. Here, this issue was addressed using yellowfin sole (Limanda aspera) in the eastern Bering Sea, for which a 43-yr otolith chronology was developed from 47 otoliths and compared with body size for 6943 individuals collected in 1987, 1994, and 1999 through 2006. Among several metrics of size normalized for age and sex, average body mass index (defined as weight/length) had the strongest relationship to the otolith chronology, especially when the chronology was averaged over the 5 yr preceding fish capture date (R² = 0.88; P < 0.001). Overall, sample-wide anomalies in otolith growth reflected sample-wide anomalies in body size. These findings suggest that otolith chronologies could be used as proxies of body size in data-poor regions or to hind-cast somatic growth patterns prior to the start of fisheries sampling programs.