Just when the market thought exchange merger fever had fizzled out, news broke this week that Oslo Børs was to buy Fish Pool, the world's largest salmon derivatives exchange, from freight exchange-operator Imarex.

Investors looking to reel in some returns from glum commodity markets take note: salmon futures prices have leapt by nearly a fifth so far this year, and are forecast to keep rising. Prices for salmon futures for March 2013 delivery have risen by 2.5% in the last month.