0-group bass were sampled from the shallow creeks of the Tamar and Camel estuaries at regular intervals from May to September in 1981 to 2000 to measure relative year-class abundance. From 1989 onwards classes were generally strong, especially those of 1989, 1992 (Tamar only), 1995 and 1998. Sampling at age-4, before departure from the nursery at the onset of adolescent movements, gave broadly similar relativities. Numbers were greater, and growth faster, in the Tamar than in the smaller and cooler Camel. Temperature was an important factor in both abundance and growth. Occasional major differences in abundance between the two estuaries were reported. Factors which might bias the age-4 result are considered. Other estuaries on the south side of the south-west peninsula, sampled less frequently, reflected Tamar abundances; others on the north side reflected Camel abundances. Limited analysis of stomach contents of older juvenile bass often present in the same habitats revealed no evidence of cannibalism on 0-groups. The shallow creeks of the Tamar and Camel were deserted in winter but a deeper creek on the Taw, frequented throughout winter, was sampled monthly in the 1982–1996 winters to measure losses, if any, in cold periods. In the mainly mild winters, losses were infrequent and small except in the five-week cold spell of early 1986, when the 1985 class suffered an estimated 58% loss in the Taw and possible total loss in the Camel and the Tamar. Sudden heavy flooding of the estuaries caused no apparent losses when they occurred in late summer and autumn but might be damaging if they occur soon after post-larvae arrive.