Intertidal collection within the Berwickshire and North Northumberland Coast European Marine Site : investigating the scale, locale, and ecological impacts of harvesting Arenicola marina, Arenicola defodiens, and Littorina littorea

Abstract

Robust evidence of fisheries impacts, fishing intensity, and spatial distribution of fishers are required, driven by a push towards evidence based management, and the trend towards Marine Spatial Planning (MSP). Intertidal fisheries have received considerably less research and management attention to date compared to inshore and offshore counterparts. The need for additional intertidal fisheries data, specifically within European Marine Sites (EMS), has been identified. This research focusses on the collection of lugworms Arenicola marina and Arenicola defodiens, and periwinkle Littorina littorea within the Berwickshire and North Northumberland Coast European Marine Site (BNNC EMS), UK. This thesis aims to provide an interdisciplinary evidence base for marine managers and future research to build upon. Comparisons of sites experiencing a gradient of fishing pressure at the EMS scale, combined with small scale experimental disturbances, revealed the potential and actual impacts of local harvesting regimes. Data on the target species revealed no significant impacts between sites, suggesting that at current collection intensities, Northumberland populations of neither periwinkle nor lugworm are reduced or altered by fishing beyond naturally occurring levels. Community assessments revealed no observable impacts on the rocky shore, but sediment communities were negatively impacted with reductions in infaunal abundance and taxonomic richness, and altered community structure observed between sites and treatments. Recovery timescales were investigated and discussed. Fisher distribution was mapped from shore observations, highlighting collection hotspots, and combined with questionnaire data to estimate biomass removal, with economic value discussed. Adherence to current fisheries regulations were ii investigated, revealing a shortfall in existing enforcement measures, with illegal night time collection especially prevalent at some sites. Commercial and recreational collection characteristics were contrasted, and identification features recommended. Finally, spatial models of habitat suitability, sensitivity, and vulnerability were produced for the lugworm fishery, assessing the appropriateness of current spatial management measures. The spatial extent of existing bait digging byelaws included most of the highly vulnerable areas identified in the model outputs, with suggestions to further improve the coverage discussed.