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Size and abundance data were compiled and collated for blue cod Parapercis colias and rock lobster Jasus edwardsii from New Zealand marine reserve (MR) studies for a meta-analysis to test the null hypotheses that reserve status does not affect the size or abundance of either species. Calculation of meta-analysis effect sizes revealed that significant differences in effect size existed among studies, meaning that the biological response to MR status of both species in terms of their changes in size and/or abundance differed significantly among the MRs. Analysis revealed that blue cod were bigger inside compared with outside MRs in 9 of 10 studies and were more abundant inside MRs in 8 of 11 studies, and that rock lobster were bigger inside the MRs in 12 of 13 studies and more abundant inside the MRs in 11 of 14 studies. These findings indicate that MR protection can result in more and bigger individuals soon after the establishment of the MR (mean of 6.5 yr for blue cod, 8.5 yr for rock lobster) despite small sample sizes of studies (≤10 for blue cod, ≤14 for rock lobster). Focused comparison tests did not reveal any relationship between rock lobster or blue cod size or abundance and either age or area of MRs. Our results demonstrate that no-take MRs are valuable conservation tools for species such as blue cod and rock lobster (and probably also for other exploited species with similar life history characteristics and habitat requirements) and that statistically detectable conservation benefits are apparent after only a few years of protection.

The possible effects that marine reserve protection has had on densities of some reef fish and large invertebrates were investigated near Leigh (north-eastern New Zealand) by a series of sampling programmes between 1976 and 1988. Fish counts at intervals during the 6 years after the initial establishment of the Cape Rodney to Okakari Point Marine Reserve in 1975 suggested that red moki {Cheilodactylus spectabilis) had increased in abundance whereas five others had remained at approximately constant densities. A comparison of data between 1978 and 1988 also revealed few consistent differences in fish abundances. A detailed survey in 1988 between sites inside and outside the marine reserve showed no clear patterns for sea urchins (Evechinus chloroticus) and several fish; trends for increased abundances in the marine reserve of fish such as snapper Pagrus (=Chrysophrys) auratus, blue cod (Parapercis colias), and red moki; a very striking increase in numbers of rock lobsters (Jasus edwardsii) within the marine reserve; and an obvious trend for increased size of snapper in the marine reserve. Most of the trends, however, were not statistically significant, owing largely to the low power of the tests used. Although it is now generally accepted that the creation of marine reserves such as the one at Leigh results in increased abundances of M89O25

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