Noninvasive, epigenetic age estimation in an elasmobranch, the cownose ray (Rhinoptera bonasus)

Area of Science:

• Marine biology
• Genetics
• Conservation science

Background:

• Accurate age estimation is vital for elasmobranch population assessment and conservation.
• Traditional methods like vertebral aging are lethal, costly, and time-consuming.
• Non-invasive techniques are needed for sustainable elasmobranch management.

Purpose of the Study:

• To develop and validate epigenetic clocks for non-lethal age estimation in cownose rays (Rhinoptera bonasus).
• To identify age-correlated DNA methylation patterns in accessible tissues.
• To provide a more accurate and efficient alternative to traditional aging methods.

Main Methods:

• Utilized aquarium-born cownose rays with known birth dates (0-21 years).
• Employed Enzymatically-converted restriction site-associated DNA sequencing (ECrad-seq) to analyze DNA methylation.
• Developed epigenetic clocks using fin clips and whole blood samples.

Main Results:

• Epigenetic clocks achieved high accuracy (MAE < 0.75 years) and precision (R² > 0.98).
• Identified age-associated CpG sites across both fin and blood tissues.
• A multi-tissue clock demonstrated strong performance (MAE < 1 year, R² = 0.97).
• Successfully estimated ages of wild-caught individuals with over 22 years in managed care.

Conclusions:

• Epigenetic clocks provide a reliable, non-invasive method for aging cownose rays.
• This approach has significant implications for elasmobranch research, conservation, and management.
• Opens avenues for developing similar epigenetic tools for other elasmobranch species.