Effective protection of essential fish habitat requires understanding fish spatial ecology - lessons learnt from protected European bass nursery areas

Spatial management is a widely used technique to protect sessile species or habitats. Protection of essential fish habitat is increasingly
being recognized globally within fisheries management policies, requiring further practical assessments within temperate fisheries. We
provide a case study for the efficacy of spatially protecting nursery sites for a highly mobile species—the European bass (Dicentrarchus
labrax). Using acoustic telemetry, 146 individual fish were tracked for up to 812 days across three independent protected bass nursery
areas in the Southwest UK. Within site boundaries commercial fisheries are seasonally restricted to protect vulnerable life stages.
Tagged fish were re-detected >5 million times. Detections at receivers highlighted activity hot spots at or near the seaward entrance
to each site. Generalized linear modelling estimated high variation in the seasonal presence/absence of fish. Due to variation in the
seasonal timing and spatial boundaries of protected sites, the amount of time fish were protected ranged 1.9%–27.4%. Further work is
required to link these findings to population processes e.g. mortality, growth or recruitment. We, however, highlight the vital need to
consider movement patterns to ensure boundaries of spatially protected areas are relevant to species they are designed to protect.