Transfer of “seed” material from fishing to on-growing facilities

Glass eels are very valuable and also very delicate. The method of capture should be as “passive” as possible to limit damage and to minimize the losses that occur between the fishery and the capture-based aquaculture facilities. Trawling compresses the glass eels with small fish and detritus. Their integrity becomes damaged, and osmoregulation and defence mechanisms are compromized. In France, mortalities during catching, handling and transport from its great estuaries are more than 20 percent (Ciccotti, Busilacchi and Cataudella 1999).

Initially the glass eels appear to be normal, especially when stored in salt water. Following further handling and transportation, after a few days storage on the farm, it is common to notice that the glass eels start to swell and become opaque; death follows quickly. Good management, increasing the temperature to 25-28°C and, in some cases antibiotic treatment, can help to reduce mortalities during transport, but starting with good quality glass eels is the best solution (www.glasseel.com).
Methods for transferring captured eels from the capture area to farms are more or less standardized worldwide. Transport ashore is made in aerated tanks for European eels, and in wooden boxes (after a day in tanks or bamboo baskets) for Japanese eels.

Elvers of European eels are transported to on-growing facilities in polyethylene bags at the temperature of 4-7°C (Pillay 1995).
American eel (A. rostrata) elvers are sensitive to low oxygen levels (Facey and Van Den Avyle 1986) and require 11 ppm DO2 for their transport to farming facilities (Sheldon 1974).