# Axolotls retain fertility throughout lifespan

## TL;DR

Axolotls maintain fertility throughout their lifespan, showing limited reproductive decline with age.

## Contribution

This study provides the first large-scale assessment of axolotl fertility across lifespan using long-term breeding records.

## Key findings

- Axolotl fertility peaks after maturation and declines gradually until age 4.
- Older axolotls retain functional fertility within their average lifespan.
- Early-stage oocytes persist in axolotls until advanced age.

## Abstract

Salamanders such as axolotls exhibit exceptional regenerative abilities and longevity. While many ectothermic species reproduce into old age, axolotls have been proposed to experience post-maturation fertility decline.

We hereby present a large-scale assessment of axolotl reproductive potential across lifespan based on over 15 years of mating records from captive breeding. We show that axolotl egg number, egg quality, and mating success rates peak after sexual maturation and gradually decline up to 4 years of age, with rates stabilising after the early-life maturation period. We also report that axolotls preserve early-stage oocytes until advanced age and describe the progression of follicular atresia in salamanders.

By breeding older individuals, we show that axolotls retain functional fertility until ages within their average lifespan, exhibiting limited reproductive senescence. This study offers insights of relevance to developmental and ageing studies and provides a comparative model for understanding how long-lived vertebrates maintain reproductive capacity and support longer survival through time.

The online version contains supplementary material available at 10.1186/s12915-026-02545-3.