Scotland’s anglers have warned that wild salmon stocks are at crisis point after they caught the lowest number on record last year.

Official data from the Scottish government showed just over 37,000 wild salmon were caught in 2018, the lowest since records began in 1952 and 67% of the average over the past five years.

Nearly all the salmon taken by anglers in Scotland are returned to the river alive. River management boards and conservationists blame a variety of factors for the decline, including climate change leading to warmer seas and changes in food supply, dams and weirs on river systems blocking migratory routes and commercial salmon farming.

Angling is a significant source of income in parts of rural Scotland, and critics of fish farming argue that salmon farms attract swarms of sea lice, a parasite that feeds on live fish and attacks wild salmon nearby. Escaped salmon sometimes cross-breed with wild salmon and compete for food.

Roseanna Cunningham, the Scottish environment secretary, said she was alarmed by the figures. “The decline in wild salmon numbers is of great concern, and I’m determined that we safeguard the future of this important species,” she said.

The Scottish government was trying to address the problem with other agencies, Cunningham said, including spending £500,000 on research into the causes of the slump in numbers. A government fund had put £5m into taking out or modifying weirs and dams.

Alan Wells, the chief executive of Fisheries Management Scotland, which represents the fisheries boards, commissioners and trusts that run and police the affected rivers, said wild salmon conservation should become a national priority.

The data confirmed a downwards trend over the past decade, with numbers falling every year since 2010, apart from slight recoveries in 2015 and 2016.

“Salmon catches in Scotland have reached the lowest levels ever recorded. Figures for 2018, taken together with those of recent years, confirm this iconic species is now approaching crisis point,” Wells said.

“Some of the factors impacting on wild salmon stocks may be beyond human control. But Scotland’s government and regulatory authorities now have a historic opportunity to do everything in their power to safeguard the species in those areas where they can make a difference.”