From endangered to sustainable: Multi‐faceted management in rivers and coasts improves Atlantic salmon (Salmo salar) populations in Denmark

Abstract

The status of Atlantic salmon, Salmo salar L., over the last decades has been of concern across its entire distribution area. Its anadromous nature exposes the species to human pressures in both freshwater and marine environments, and over long periods, thus exacerbating its decline. Given its value within the food industry, the recreational angling community as well as culturally, the status of Atlantic salmon is regarded as a matter of national and international conservation interest, providing great incentive for its management. The literature currently lacks specific examples of successful and unsuccessful management strategies and practices for Atlantic salmon populations at a broader scale. To address this, the present article describes how the multi‐faceted management approach taken for Danish Atlantic salmon, which included changes in legislation, stocking practices, habitat restoration, population genetics and barrier removals, successfully rehabilitated salmon populations in four major Danish rivers. Specific recommendations are provided for the successful management of Atlantic salmon elsewhere.

Data collection systems and methodologies for the inland fisheries of Europe

“…Over the last 24 years, using recommendations from NASCO (North Atlantic Salmon Conservation Organization), stating that all populations should be maintained above their conservation limits (NASCO, 2009), and the EU Water Framework Directive, which has required member states to make significant changes in national water management plans, Denmark has successfully 'brought back' wild Atlantic salmon from the brink of extinction (Koed et al, 2019).…”

“…Denmark's success in restoring its salmon population is due mostly to the multifaceted management approach used -addressing major issues related to habitat quality and quantity, legislation and stocking. When populations are on the brink of extinction (as was the case in the early 1990s in Denmark), all possible strategies should be employed simultaneously to avoid wasting valuable time, because this is what practitioners often face in reality (Koed et al, 2019).…”

“…In all rivers, the populations decreased dramatically during the 20th century, primarily due to habitat destruction, the building of impassable barriers to migration, nutrient impact from agriculture, and pollution. The River Gudenå was the only eastern Jutland river with its own salmon stock, which subsequently disappeared as a result of the installation of a large hydropower dam in 1920 (Aarestrup et al, 1999;Jepsen et al, 1998;Koed et al, 2002Koed et al, , 2019. Since the 1950s, it was thought that the salmon populations were eradicated from all Jutland rivers, with the exception of River Skjern.…”

“…Furthermore, stocking became viewed as an approach to support natural reproduction in the streams where self-production from natural spawning was insufficient, rather than the prime method to restore salmon populations. Together, these management strategies have led to much healthier salmon populations in Denmark (Koed et al, 2019).…”

Restored river habitat provides a natural spawning area for a critically endangered landlocked Atlantic salmon population

“…it is combined with releases of juveniles originating from hatchery crosses using wild broodfish [29,30]. In the River Ala-Koitajoki, spawning habitats were restored and water flow was increased to create a new natural spawning and reproduction area for the landlocked Atlantic salmon population, where transferred mature fish could spawn naturally.…”