Fishing is expected to alter the spatial heterogeneity of fishes. As an effective index to quantify spatial heterogeneity, the exponent b in Taylor’s power law (V=aM^b) measures how spatial variance (V) varies with changes in mean abundance (M) of a population, with larger b indicating higher spatial aggregation (i.e. more heterogeneity). Theory predicts b is related with life history traits, but empirical evidence is lacking. Using 50-year spatiotemporal data from the California Current Ecosystem, we examined fishing and life history effects on Taylor’s exponent by comparing spatial distributions of exploited and unexploited fishes living in the same environment. We found that unexploited species with smaller size and generation time exhibit larger b, supporting theoretical prediction. In contrast, this relationship in exploited species is much weaker, as the exponents of large exploited species were higher than unexploited species with similar traits. Our results suggest that fishing may increase spatial aggregation of a species, likely through degrading their size/age structure.