Abstract

The fork length (LF) of individual chub Leuciscus cephalus in English riverine populations at the end of their first growth season varied considerably, ranging from <25 to >70 mm. This had a significant influence on the subsequent growth of individuals over their lifetime. Chub of small LF at age 1 year generally produced smaller annual growth increments throughout life than those of longer LF at age 1 year, although they had the potential to attain greater ultimate LF. This variability in LF at age 1 year resulted, at least in part, from multiple spawning events over a protracted period, that caused variation in the growing seasons for 0 year group chub of the same year class. Since the adult population contained individuals that only attained LF of <25 mm at the end of their first growing season, it is possible that LF at age 1 year may not be such a major precursor to strong chub recruitment as previously thought.