Where on Earth did all those salmon come from?

They do take fish quite seriously in Canada. On the East Coast, the decimation of cod stocks wiped out the Newfoundland fishing industry, leaving a shadow of a trade which employed thousands. On the West Coast, it's all about salmon.

Last year, the number of salmon returning to spawn in the Fraser River system was at its lowest in recorded history, just 1.5 million, and there were genuine fears that salmon fishing in British Columbia might go the same way as cod fishing on the Grand Banks. The usual suspects were blamed, sea lice from farmed salmon, predation by sea lions, anything to avoid the conclusion that overfishing was possibly to blame.

However, it had been expected that numbers would rebound this year. Estimates based on a historically accurate model indicated that, probably, about 10 million would return this year. And then the model crashed...

Estimates were gradually increased, until last week, when the evidence emerged that the Fraser River salmon run was going to be the best since 1913, when some twenty-five million salmon surged upstream (let's just say that there were some very happy bears in British Columbia that year). Indeed, there are now expected to be as many as thirty million, with salmon fisherman filling their nets to bursting point and prices at rock bottom levels. There are even concerns that too many salmon will reach the spawning grounds, where water levels are low after a dry summer.

Scientists have their theories as to the cause of this bounty, and the favourite is linked to a drop in water temperatures following changes in ocean currents. Whatever the cause is though, it is potentially good news, as it implies that fish stocks, if properly managed, are more resilient than feared.

And it'll be another good year for the bears...