Abstract

No-take Marine Protected Areas (MPAs) are widely used to conserve biodiversity and rebuild fish populations, but their ecological benefits can vary among locations and habitats. Cod Grounds Marine Park protects a key aggregation site for the critically endangered grey nurse shark (Carcharias taurus), providing an opportunity to assess whether no-take protection is associated with enhanced fish assemblages and prey availability. Fish communities were surveyed using baited remote underwater video systems (BRUVs) at protected and nearby fished reefs across seven sampling periods between 2015 and 2018. Protected reefs supported different assemblages, as well as approximately 9% more species and 50% greater fish abundance than fished reefs. Species identified as potential grey nurse shark prey were approximately 55% more abundant inside the reserve, and grey nurse sharks were recorded exclusively within the marine park. In contrast, water temperature and variation in compliance effort explained little variation in fish assemblage metrics. These findings highlight the ecological value of protecting key aggregation habitat for grey nurse sharkss by supporting richer reef fish communities and greater prey availability.

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