Marine larval hatchery technology:Microbial management and immune system ontogeny in European eel

• Main Author: Bandara, Kasun Anuruddha
• Format: Book
• Language: English
• Published: DTU Aqua 2023
• Subjects: /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; name=SDG 14 - Life Below Water; Anguilla anguilla
• Online Access: https://orbit.dtu.dk/en/publications/1022a0c1-a9f6-405d-bf8b-2f9dd7ac3b42; https://backend.orbit.dtu.dk/ws/files/351099404/Thesis_1_.pdf

The European eel ( Anguilla anguilla ) was once a common fish in streams, lakes and fjords with considerable economic and social importance. It has a high market value and has been a dedicated target for both commercial fisheries and aquaculture in Europe. Since the turn of the century, however, fishing has been in decline, and the same applies to aquaculture, which is based on wild-caught glass eels. The glass eels, which are in a juvenile stage, are caught in targeted fisheries to supply farms with fry and assist in restocking. Today, the European eel population is under pressure due to historically low recruitment levels of glass eels and designated as "Critically Endangered" on the IUCN Red List. In response, ICES recommends a complete cessation of eel fishing at all stages to facilitate stock recovery. If we are to preserve the eel as a food fish, a sustainable solution would therefore be to develop hatchery techniques and close the eel's life cycle in captivity. Hatchery production of glass eels also has the potential to contribute to the management of European eel in the long term. However, establishing hatchery technology for breeding European eel in captivity is challenging due to the eel's complex life cycle and a distinct lack of knowledge about the reproductive stages and early life history in nature. The eel has life stages in the sea as well as in continental waters. The reproduction of European eel involves a migration over a long distance to the spawning area in the Sargasso Sea, where the earliest larval stages occur. From here, their larvae, the so-called leptocephalus larvae, are transported by ocean currents to the coasts of Europe and North Africa, where the leaf-shaped larvae transform into a juvenile stage, the glass eel. Glass eels, which are small and transparent, find their way into freshwater systems such as lakes, marshes and rivers or remain in coastal waters. Further on, they become yellow eels and later silver eels, which migrate to the Sargasso Sea to spawn. By the time they start ...