Fish nurseries in a changing world: towards functional indicators of habitat quality

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Scientific Background The identification and conservation of "Essential Fish Habitat" is emerging as a research, management and policy priority. Protecting habitats required for every life-stage is necessary to create sustainable fisheries and conserve threatened species, but knowledge of fish habitat needs is very limited, particularly for juveniles. Juveniles are often critically dependent on shallow, inshore areas which are heavily impacted by human activities. Little is known about these young stages because they are rarely targeted by commercial fisheries or fisheries-independent surveys. Currently, juvenile habitat quality is typically assessed simply on the basis of the abundance of fish they contain. Functional indicators such as fish growth, survival and movement into the adult population are often overlooked, but are essential to quantifying the importance of different areas as fish nurseries. Methodology This PhD project involves 1) laboratory experiments to develop novel molecular and geochemical indices of feeding, growth and movement in free-ranging juvenile fish; and 2) extensive field work in the Severn Estuary to apply these tools in a real-life setting and identify key habitat needs of a commercially valuable species, the common sole Solea solea. Training The student will be trained in a range of skills, building on core expertise of the supervisors in molecular growth indices, DNA metabarcoding for diet characterisation, and biogeochemical tracers for trophic and connectivity reconstruction: key techniques relevant not just for fisheries, but broadly across environmental research disciplines. The consultancy 'Ocean Ecology' (CASE partner) and the Devon and Severn Inshore Fisheries and Conservation Authority (collaborative partner) offer a unique platform for sampling challenging estuarine environments and experience in applying innovative research to support marine policy and management decisions.