Fish communities were sampled at 14 sites along the lower 120 km of the Fra
ser River, British Columbia by beach seine four times in 1972-1973 and thre
e times in 1993-1994. Of the 37 species collected, peamouth chub, largescal
e sucker, starry flounder, and northern squawfish were predominant in eithe
r density or biomass. Densities and biomass of most species and all fish co
mbined were higher in 1993-1994. Strong rank correlations of species abunda
nce or biomass indicated that the overall fish community structure was very
similar in both periods. At smaller spatial scales (reaches of 2-3 sites)
and shorter time scales (by season), less than half the comparisons showed
any significant correlation indicating changes in community composition. La
rgescale sucker, one of the largest contributors to biomass in both periods
, showed decreased abundance, i.e., lower density, lower biomass, and large
differences in the size-frequency distribution, specifically very low repr
esentation of small size classes. Other species, especially small-bodied fo
rms, generally increased in numbers. Despite large changes in the lower Fra
ser River ecosystem in the past 21 years, the overall fish community has sh
own remarkably little change over that interval.