The extent to which fish populations can compensate for changes in stock si
ze has an important bearing on the capability of stocks to survive fishing
and other pressures. The degree of compensation can be linked with the exte
nt to which juvenile fish populations concentrate during their early life h
istory. Populations that concentrate into nursery grounds during the first
year of their lives may approach the carrying capacity of their habitat in
years when settlement is high, and this limitation may then moderate the po
pulation size. In other species, pelagic throughout their juvenile lives, t
here is little or no concentration effect. A statistical analysis is descri
bed comparing best-fitting stock-recruitment relationships fitted to publis
hed data for a large number of stocks. It is shown that in those species th
at do not concentrate the relationship is typically close to linear, wherea
s in those that concentrate the relationship tends to be sharply curved awa
y from a straight line. Theory suggests that in those species that concentr
ate the scatter of recruitment around a stock-recruitment relationship is l
ess variable than in those that do not concentrate. Analysis of the data su
ggests that patterns in variability are broadly in line with this hypothesi
s. (C) 2000 International Council for the Exploration of the Sea.