Yes, we do have a basic understanding of how eels reproduce, although many details remain mysterious, especially about their behaviors in the wild. Eels reproduce through external fertilization: male and female eels release sperm and eggs into the water, where fertilization occurs outside of their bodies. Most notably, species like the European eel and American eel migrate thousands of miles to a specific breeding ground in the Sargasso Sea in the Atlantic Ocean to spawn. Their larvae then spend years migrating back to freshwater rivers and habitats where they mature. However, much about their reproductive journey, including how they navigate these vast distances and what exactly happens when they arrive, is still not fully known. Some research has been done on eel reproduction in captivity with hormone treatments inducing spawning, but it's uncertain how closely that mimics natural reproduction. Additionally, eel larvae often show high mortality rates and abnormalities in captivity due to breeding conditions, though these have improved over time. So in summary: Eels reproduce by externally releasing eggs and sperm in the ocean, travel far to their spawning sites, and send their larvae back to freshwater, but many specific behaviors and details remain partially unknown because of the challenge of observing them in their natural deep-sea environment.
