The reason why eels cannot be hatched in farms is primarily due to their highly intricate life cycle. Eels go through a series of developmental stages, starting from eggs to larvae, then transforming into glass eels and eventually reaching the adult stage. Each stage requires specific environmental conditions and cues that are difficult to replicate in artificial settings.
One of the main challenges in eel aquaculture is reproducing the spawning behavior of adult eels. Eels are catadromous, meaning they migrate from freshwater to the ocean to spawn. The exact triggers for their migration and spawning are still not fully understood, but it is believed to involve a combination of hormonal changes, environmental cues, and possibly even geomagnetic navigation. Replicating these complex factors in a controlled environment is currently beyond our capabilities.
Another hurdle is the difficulty in obtaining fertilized eel eggs. Eel eggs are buoyant and can drift for long distances in the ocean currents before hatching. This makes it extremely challenging to collect and fertilize the eggs in a controlled manner. Even if we were able to obtain fertilized eggs, providing the necessary conditions for their development is a major obstacle. Eel larvae require a specific range of water temperatures, salinity levels, and food sources that are difficult to maintain in a controlled environment.
Furthermore, the metamorphosis from larvae to glass eels is a critical and delicate phase in the eel life cycle. During this transition, eels undergo significant morphological and physiological changes, including the development of their characteristic pigmentation and the ability to adapt to different water environments. Replicating these changes and ensuring the survival and proper development of the larvae into glass eels is currently not feasible in hatchery settings.
The reliance on wild-caught glass eels for stocking aquaculture ponds is a result of these challenges. Glass eels are young eels that have just undergone metamorphosis and are transparent in appearance. They are collected from estuaries and coastal areas during their upstream migration. While this method provides a means to stock eels in aquaculture ponds, it is not sustainable in the long term, as it puts pressure on wild eel populations.
Efforts are being made to overcome these challenges and develop sustainable eel aquaculture practices. Research is being conducted to better understand the eel’s reproductive behavior, optimize larval rearing techniques, and investigate the possibility of artificial reproduction. However, as of now, the complexities of the eel life cycle pose significant obstacles to successfully hatching eels in farms.