An investigation into the subtidal species and habitats of a newly established No-Take-Zone, Portelet Bay, Jersey, Channel Islands.

Multilateral environmental agreements, including the Convention on Biological Diversity, have pushed
nations to designate increasing amounts of the marine environment as Marine Protected Areas (MPA).
No-Take-Zones (NTZ) are a form of highly protected MPA, prohibiting the extraction of all marine
resources. In Jersey, Channel Islands, Portelet Bay is home to the country’s only NTZ, implemented on
the 2nd of May 2022. This study used Stereo-Baited-Remote-Underwater-Videos (stereo-BRUVs) to
explore changes in the total diversity and abundance of species inside and outside the NTZ over three
years. Further, stereo-BRUVs were trialled for the first time to generate length measurements of
species inhabiting the bay. This study indicated a significant increase in the total abundance of Portelet
occurred between 2021 and 2023, whilst no significant increase in total abundance was observed at
the control site across these years. No significant changes in diversity were reported. Length
measurements were used to generate age estimates for individual species, giving insights into juvenile
and adult species inhabiting the bay. Increased numbers of length measurements will help detect
future changes in length-frequencies and give insights into the biological and ecological factors,
including species sex, reproductive maturity, and trophic interactions. Sustained and enforced
protection of this NTZ is vital for the validity of long-term monitoring. Observations made in this small
NTZ have the potential to contribute to global scientific research on highly protected marine areas
and wider changes in coastal marine ecosystems.