Variability in growth rate in European eel Anguilla anguilla (L.) in a western Irish catchment

The length, age and growth rate of female silver :els trapped in the Burris hoole system, western Ireland, were investigated in 1987 and 1988. Length r anged from 40cm to 100cm, and age from 8 to 57 years. Of the total sample o f 8612 eels measured, 0.7% were larger than 62cm: 0.6% in 1987 and 0.7% in 1988. Annual growth rates were generally faster for the larger eels (> 62cm ). The growth curve for eels less than or equal to 62cm decreased annually, approaching an L-infinity of 99.9cm, and the curve for eels > 62cm was alm ost linear over the entire period of growth. This study has shown that eels of exceptional size regularly reach the mature silver stage and migrate, e ven at ages as great as 57 years.