Seascape ecology of juvenile gadoid nursery areas

Availability of juvenile fish habitat provision can impact recruitment. This study focused on identifying which environmental variables characterize the juvenile habitats of three commercially important gadoid species: Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus). Stereo baited remote underwater video surveys were conducted in the South Arran Marine Protected Area between 2013 and 2019 to collect presence/absence data on juvenile gadoids (>20 mm <120 mm) and demersal and epibenthic communities. Data were analysed using binomial generalized additive mixed models. The results revealed spatial segregation among species, each favouring distinct habitats. Predictive modelling suggests a substantial increase in presence probability from 0.25 to 0.75 as the inverse Simpson's diversity index increases, suggesting that biodiversity appears to be associated with species distribution. Boundary regions between seabed types were associated with variation in species distribution, underlining the importance of seascape heterogeneity. This study underscores the importance of conserving and restoring benthic and epibenthic biodiversity across spatially heterogeneous landscapes. Consequently, reducing benthic pressures could promote early survival for these species, thereby supporting broader ecosystem health and fisheries management goals.