Mapping inshore fisheries: Comparing observed and perceived distributions of pot fishing activity in Northumberland

Abstract

Marine spatial planning (MSP) is increasingly promoted as part of an ecosystem-based approach to marine resource management. Impacts of MSP may be particularly great in inshore fisheries, yet despite their vulnerability, assessing potential impacts of spatial measures on inshore fisheries is limited by data scarcity, and the comparability of patterns of fishing activity produced by different data sources is poorly understood. This study contributes to the debate around information needs for MSP by describing the distribution of lobster potting activity at four ports in Northumberland, UK, using two sources of spatial data: observed fishing vessel sightings by patrol vessels and perceived fishing activity elicited through interviews with local fishers. The comparability of the distributions of potting activity mapped by the two datasets was explored using Mantel tests and overlap of fishing hotspots identified. Fishing activity at all ports tended towards an aggregated or patchy distribution, with hotspots located in inshore areas in close proximity to vessels' home ports. The two datasets were correlated at each port, though the strength of correlation varied among ports, being greater in ports with more highly aggregated fishing activity. Results suggest that vessel sightings are likely to better represent variable intensity of fishing activity, while interview data may more accurately capture the absolute extent of grounds important to fishers. This study highlights some of the merits and limitations of two available data sources currently used to inform fisheries management and marine conservation planning, and outlines an approach to assessing the consistency of datasets in describing the spatial distribution of activity. Given the limitations of individual datasets, we recommend triangulation of available data to inform MSP, alongside qualitative data on fishers' behaviour.