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Summary1. Marine protected areas (MPAs) have been advocated for the protection of threatened marine mammals, but there is no empirical evidence that they are effective. In 1988, the Banks Peninsula Marine Mammal Sanctuary was established to reduce gillnet mortalities of Hector's dolphin Cephalorhynchus hectori, an endangered dolphin species endemic to New Zealand. This study assesses the effectiveness of the MPA in improving the survival rate of Hector's dolphin at Banks Peninsula. 2. Over 21 years, we undertook photo-identification surveys of Hector's dolphins along standardized transects from small outboard-powered boats. From 1986 to 2006, we photographically captured 462 reliably marked individuals. We estimated mean annual survival during the pre-sanctuary and post-sanctuary periods by applying a Bayesian random effects capture-recapture model to the data. Population growth was estimated from population simulations using a stage-structured matrix model. 3. We estimate a 90% probability that survival has improved between the pre-sanctuary and postsanctuary periods, with estimates of mean survival probability increasing by 5AE4% (from 0AE863 to 0AE917). This improvement in survival corresponds to a 6% increase in mean annual population growth (from 0AE939 to 0AE995). 4. Synthesis and applications. Our study demonstrates improvement in a demographic parameter of an endangered marine mammal species following conservation action. Our results provide evidence that area-based protection measures can be effective for marine mammals. We note that estimating demographic parameters in marine mammals requires many years of data to achieve sufficient precision to detect biologically meaningful change. MPAs should be established with a commitment to long-term monitoring.

Knowledge about home ranges is essential for understanding the resources required by a species, identifying critical habitats, and revealing the overlap with anthropogenic impacts. Ranging behavior of Hector's dolphins (Cephalorhynchus hectori) was studied via coastal photo-ID surveys in the Banks Peninsula Marine Mammal Sanctuary (BPMMS) between 1985 and 2006. Univariate kernel density estimates of alongshore home range were calculated for 20 individuals with 15 sightings or more. For each individual, sighting locations were transformed into a univariate data set by projecting sightings onto a line drawn 1 km from the coast and measuring the distance along this line relative to an origin. Sightings were weighted by survey effort. Ninety-five percent (K 95 ) of the density estimate was used as a measure of alongshore home range, and 50% of the estimate (K 50 ) was used to reveal core portions of coastline where dolphins concentrated their activity. The mean estimates of K 95 and K 50 were 49.69 km (SE = 5.29) and 17.13 km (SE = 1.89), respectively. Four distinct hubs were apparent where the core areas of different individuals coincided. Three of the dolphins' alongshore ranges extended beyond the current northern boundary of the BPMMS, raising fresh concerns that the sanctuary is not large enough. Proposed changes to gill netting regulations, if enacted, will result in the alongshore ranges of all the dolphins in our study being protected.