Abstract
Orange roughy from six localities around the southern coasts of Australia showed no evidence of genetic subdivision when the products of 11 polymorphic enzyme loci were analysed electrophoretically. Samples ranged in size from 84 to 171 per locality. Gene frequencies were very similar in samples taken from New Zealand. The amount of total genetic diversity attributable to subdivision among samples is estimated at 0.55 to 0.22%, but bootstrapping procedures showed that much of this diversity could arise from sampling error. A minimum of around 200 migrants per locality per generation would be sufficient to maintain the observed genetic homogeneity, although actual numbers migrating are likely to be greater than this.