Is there evidence of over-exploitation of mussel stocks on the Transkei coast?

Abstract

Reductions in the proportion and the size of brown mussels Perna perna found in shell middens, coupled with a marked decline in the density of natural populations in Transkei, have previously been cited as evidence of over-exploitation. Data from a more intensive and regular sampling programme reported here, however, show that significant differences in size composition can be detected in samples taken as frequently as one month apart. These results indicate that the comparisons made after an interval of six years, as described by previous workers, should be treated with caution.