Can amino acid racemization be utilized for fish age validation?

We investigated the relationship between aspartic acid d:l ratios and otolith-derived age estimates in Gulf of Mexico red snapper, Lutjanus campechanus (ages 1–26 years; R² = 0.89) and Caribbean yellowtail snapper, Ocyurus chrysurus (ages 2–17 years; R² = 0.84). The estimated racemization rate was 0.61 × 10⁻³ year⁻¹ for red snapper and 1.28 × 10⁻³ year⁻¹ for yellowtail snapper, reflecting temperature differences between study regions. Mean jackknifed error in ages predicted from aspartic acid d:l was 1.70 ± 0.39 years for red snapper and 1.57 ± 0.41 years for yellowtail snapper. Results suggest amino acid racemization may be an effective tool for direct age estimation and potentially age validation in fishes.