A population model is developed and used in conjunction with the results of a study of an unexploited population of paua(Haliotis irisMartyn) to examine the historical pattern of recruitment and yield per recruit. AsH. iriscannot yet be aged, the population model uses size rather than age classes, but is structurally similar to the Leslie matrix model. Simulations suggest that the observed population size structure resulted from a short (about 5 year) period of high recruitment, preceded and followed by longer periods of low recruitment. Yield per recruit analysis shows that the present minimum legal size for the fishery (127 mm) provides close to the maximum yield per recruit for most stocks, although yield per recruit could be increased in some areas by a reduction in minimum legal size.