58. A discussion was led by Boëtius and covered a wide range.
59. Anecdotal data for the River Severn suggested long-term fluctuations which might be similar to those observed in recent times. Catches had been good in the 1890s and poor in the 1930s. The Loire showed a similar low level in the 1930s. The fact that many hundreds of tonnes of glass eels have been caught in the Loire in good seasons suggested that natural mortality could be extremely high.
60. The Baltic had never had a large immigration at the glass eel stage, being supplied largely by juvenile eels. Ascending eel in Finland are of average length 35 cm. Due to a number of factors, including the building of hydro dams, stocking is now needed to maintain the populations. Rates up to 1 000 individuals per ha per year have been quoted for Sweden. Density-dependent mortalities were not observed by Klein Breteler below a rate of 1 500 glass eel per hectare. Sweden restricts importation of glass eel to the River Severn because of disease risk from other sources.
61. A problem exists because the effects of depletion of stock may not be appreciable until a period of 5 to 10 years has elapsed from the beginning of a period of poor recruitment. Many views on the need for action were aired, but it was agreed that there is no sound scientific basis for recommending curtailment of fishing for any life stage. Notwithstanding the lack of hard evidence, the current decline in glass eel catch could not be ignored. It was necessary to continue to draw the attention of Governments to the situation. There was full agreement that further research is urgently needed and that the methodology for more effective distribution of the existing stocks was well established. It was either in preparation or in action in particular countries.
