Aggregation, production and spillover: the cumulative effect of man-made offshore structures on fish

“Spillover effects” are a well-known benefit of marine protected areas but have not been studied in relation to offshore structures in the North Sea and data on the spatial extent of fish aggregations beyond the immediate vicinity are sparse.

It is well known that certain fish species congregate at man-made marine structures (MMS) such as oil and gas installations. However, the extent to which this reflects enhanced productivity, a behavioural phenomenon, or protection from fishing afforded by the structure is unclear.

The project will use an unmanned surface vehicle equipped with state of the art high resolution acoustic and video surveying equipment to survey the densities and spillover of fish around North Sea MMS.

Data from the surveys will be used to parameterise a high spatial resolution model of fish dynamics and movements.

The model will be used to:

• Test hypotheses about the whole North Sea scale effects of networks of MMS
• Determine the extent to which these effects arise from enhanced productivity or the protection from fishing afforded by proximity to hard substrate
• Assess the consequences of removal of MMS on the scale of the North Sea