CBC Radio's What on Earth travelled to Yukon this summer to explore how a warming climate has threatened chinook salmon, endangering not just the species but a cultural keystone for these Indigenous communities. There, it found that an unprecedented seven-year moratorium on fishing mandated by Canada's federal and Alaska's state governments, combined with other conservation efforts, may be netting some success.

This summer about 24,000 chinook were counted moving up the Yukon River at the border with Alaska. That's compared to historic lows of 12,000 and 15,000 the last two seasons, says Elizabeth MacDonald, a biologist and fisheries manager for the Council of Yukon First Nations.

The fishing moratorium has only been in place for five months.