(Convener: Appelbaum)
43. Knights reported on a simple electromechanical system for rapid screening which showed that non-feeding glass eels may have some initial preferences for invertebrate food preparations over vertebrate ones or synthetic mixtures of chemicals. However, any preferences are strongly influenced by learning once feeding begins. Implications for first-feeding in the wild and in aquaculture were discussed.
44. Appelbaum described experiments showing that average weight and SGR were not affected by substituting poultry by-product chicken meal for eels in aquaculture. Further investigations are planned on the use and economics of chicken meal.
45. Quarantine procedures for glass eels at Scandinavian Silver Eel farm in Sweden were described by Gelin. Mortality rates had been greatly reduced, particularly because of major reductions in transport time (from 24 to 17 hours) and improvements in crumb diets. Other beneficial smaller improvements were also outlined.
46. Santos and Weber described studies of chemical composition, energy content and growth of Rio Minho (Portugal) glass eels. High growth rates per feeding day were achieved in general. A possible favourable season for fishing for glass eels to achieve good growth potential was indicated and mortalities due to Ichthyophthirius infections were reduced compared to earlier experiments.
47. Santos presented Bessa's work on elvers caught in the R.Liz (Portugal) showed a clear size decrease between late November 1991 and May 1992, with a similar picture in 1992-3. The smaller elvers appear to maintain biometric parameters the best and to start feeding quickly and grow well.
48. The use of small carp for keeping clean the net guards of eel tanks was described by Appelbaum on behalf of Prilutzky. Unfed carp were kept in compartments mounted around outlets and grazed any collecting debris.
49. Moriarty collected information from members on the state of intensive eel culture in Europe. A summary of their views is given in Annex D. It appeared that the number of farms and quantity of eels produced was declining.
