The Influence of Bait on Species Observations Using Baited Remote Underwater Videos in Portlet Bay, Jersey, Channel Islands

Marine ecosystems are being increasingly degraded due to increasing anthropogenic
pressures. To mitigate these issues, Marine Protected Areas (MPAs) are a popular spatial
management tool; however, protection levels vary. No-Take Zones (NTZs) enforce the
strictest level of protection, prohibiting all extractive activities. Baited Remote
Underwater Videos (BRUVs) are an ideal survey method to monitor biodiversity within
NTZs as they are non-extractive and cost-effective. BRUVs utilise bait as a stimulant to
attract mobile fauna to the camera’s field of view. Oily fish are recommended for use as
bait; however, their effectiveness is largely based on studies in the southern hemisphere.
Only one previous study has researched the efficacy of different bait types in the
Northeast Atlantic, the results of which varied across sites. Therefore, further study is
required on this topic in this region. In this study, we analyse the influence of five bait
variables (clams, crabs, worms, mackerel, and no bait (control)) on the taxonomic
diversity, relative abundance, and faunal assemblage of the Portelet Bay NTZ, located
within the Northeast Atlantic. Our results found that the oily fish mackerel did not
perform the best. Unbaited deployments attracted the highest mean number of taxa (6.2
± 1.0), whereas crab baited BRUVs attracted a significantly higher relative abundance
(34.7 ± 14.6). No significant difference was found between species assemblages across
bait types, demonstrating that each bait type attracted similar taxa. No herbivorous
species were recorded in this study, indicating that this survey method may be missing an
entire feeding guild. We compared our findings to those of other bait studies and found
that results vary largely across study locations. Based on this, we propose that bait type
should be determined based on location rather than standardisation to ensure optimal
results. We concluded that the crab bait had the best performance when control variables
were excluded. Therefore, for future BRUV studies at Portelet Bay, we recommend using
green shore crabs (Carcinus maenas) as bait, and an alternative method should be
incorporated to survey the herbivorous community