Context The inner Queen Charlotte Sound–Tōtaranui is a focal and emblematic coastal area in New Zealand that is valued by diverse stakeholders. Fish diversity in the region is not well characterised. Aims This study sought to provide an inventory of local fish populations, determine the relative abundance of all species observed, and quantify fish biodiversity (including teleost, elasmobranch, syngnathid, chimaera, and cephalopod) in the region. Methods Baited remote underwater video, a

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... y balanced acceptance sampling design, and Bayesian spatio-temporal analysis approaches using integrated nested Laplace approximation (INLA) were employed. Key results In total, 35 species were observed over 3 years. Average site-specific levels of species abundance were low (∼3) with only modest levels of biodiversity (Shannon–Wiener value = 0.65, Simpsons index = 0.51). On the basis of spatial residuals, greater species diversity was identified in western arms of the sound. Conclusions These findings provide a useful insight into the biodiversity of fish in the region, and baseline information on the relative abundance of a variety of fish species. Implications These findings characterise the contemporary status of fish populations in the inner Queen Charlotte Sound and present a useful framework for ongoing investigations of fish populations in this, and other, inshore marine environments.