Abstract

Percilia irwini from the Andalién and Biobío River basins of south-central Chile exhibited a mean age of 1.4 years with a maximum age of 4 years. Size at age differed among river zones and males were 10% larger than females at all ages. Compared to other locations, populations of P. irwini inhabiting areas subject to industrial and domestic effluents exhibited smaller size structure. © 2009 The Authors.