Two centuries of decline and partial recovery of fish in rivers of post-industrial northeast England: lessons for global rivers in the Anthropocene

Jingrui Sun, Shams M. Galib, Martyn C. Lucas

Understanding the historical decline in ecological condition of rivers, their fish stocks, and of their restoration, offers one perspective by which contemporary threats to river fishes in less developed regions may be assessed. We explore the decline and recovery of fish populations in rivers (Tyne, Wear, Tees) of post-industrial northeast England. Before ~1850, Atlantic salmon (Salmo salar) and sea trout (anadromous Salmo trutta) were abundant in these rivers. These catchments were subject to heavy industry and urbanization, river barrier construction, and industrial pollution between ~1850 and the 1960s, during which time their fish stocks dramatically declined. Following industrial decline, closure of mines, and improvements in urban wastewater treatment, salmon and sea trout started to recover in the Tyne and Wear; these are now the most productive recreational salmon fisheries in England. Anadromous salmonid abundance in the Tees remains low, probably largely due to an estuarine barrage built in the 1990s. Fish communities in these rivers have changed over time, through natural responses and species introductions. Complex environmental impacts remain across the catchments. Many localities fail to meet ‘good ecological status’, with river fragmentation and diffuse pollution remaining key problems. We conclude that responses of river fish to industrial and urban development are long-term and cumulative. Ecological recovery of river fishes, following severe environmental impacts, requires much time and effort and is rarely fully achieved. This emphasizes the need, worldwide, to avoid severe ecological damage of river systems during their development by society.