Long-term change in a North Sea inshore fish assemblage between 1899-1913 and 2018-2019

Abstract

Marine communities have been impacted by human activities for centuries, yet historical data are rarely incorporated into modern conservation efforts and restoration targets. For inshore waters, survey data sets are typically lacking because they extend back by only a few decades, despite their ecological significance as nursery grounds for many fish species. We investigated long-term change in a demersal fish assemblage from inshore waters of the Northumberland coast (UK). We collated unique historical data (1899-1913) that were sampled using a wooden beam trawl during scientific trawling investigations, shortly after the onset of widespread mechanised trawling in the North Sea. Twelve decades later (2018-2019), we re-surveyed the same bays using a modern otter trawl. The results revealed marked declines in the abundance and diversity of the entire fish and flatfish assemblage as well as among individual species. Elasmobranchs and formerly abundant species such as grey gurnard Eutrigla gurnardus were completely absent in contemporary surveys, while dab Limanda limanda and plaice Pleuronectes platessa were the most dominant species in both periods. Changes were also detected in the size distributions of the entire fish and flatfish assemblages, with proportionally fewer large individuals recorded in contemporary surveys. These findings suggest that over a century of trawling and climate change, combined with pollution, habitat alteration and increased predation risk are likely contributors to changes in the inshore fish assemblage. This work provides further evidence of long-term decline in North Sea inshore waters and offers an invaluable benchmark for improving coastal ecosystem status.