Assessing the Ecological Impact of Jersey’s First No Take Zone: Insights from Potting Trials and Diurnal/Nocturnal Surveys

There has been a global push to increase the protection of the world’s oceans with a particular interest in increasing the coverage of Marine Protected Areas (MPAs). MPAs vary in level of protection, with No Take Zones (NTZ) serving as the highest level of protection currently imposed. In Jersey, Channel Islands, its First NTZ was implemented in 2022 within Portelet Bay NTZ (PTLNTZ), to assess its impact on biodiversity and potential for benefitting local fisheries. This study marks the 5th year of monitoring within Portelet using Baited Remote Underwater Video (BRUV) data from 2021-2025 to measure change in overall abundance, species richness and species assemblages, furthermore, Nocturnal BRUV deployments were used for the first time in 2025. Secondly, annual potting data from 2022-2025 provided insights into a shift in size and abundance of Spider crab (M. brachydactlya) and European Lobster (H. gammarus) in the NTZ. Results saw increased overall abundance within PTLNTZ, with species richness remaining unchanged. Species assemblages shifted but did not differ from the control site. Nocturnal BRUVs recorded unique species compared to diurnal deployments, yet overall patterns remained similar between PTLNTZ and the control. Within PTLNTZ, spider crab showed increases in both size and CPUE, while lobster size increased and CPUE initially rose but subsequently declined. Importantly though, lobster individuals by 2025 were significantly larger than those at all comparable unprotected sites. This study has provided evidence that NTZ protection can increase the abundance of individuals, even within a small area. Furthermore, this study provides the first evidence that NTZs can contribute to the management of commercially important crustacean species in Channel Island waters.