Haida Eddies

Haida Eddies are episodic, clockwise rotating ocean eddies that form during the winter off the west coast of British Columbia's Haida Gwaii and Alaska's Alexander Archipelago. These eddies are notable for their large size, persistence, and frequent recurrence. Rivers flowing off the North American continent supply the continental shelf in the Hecate Strait with warmer, fresher, and nutrient-enriched water. Haida eddies are formed every winter when this rapid outflow of water through the strait wraps around Cape St. James at the southern tip of Haida Gwaii, and meets with the cooler waters of the Alaska Current. This forms a series of plumes which can merge into large eddies that are shed into the northeast Pacific Ocean by late winter, and may persist for up to two years.^[1]

Haida eddies can be more than 250 km in diameter, and transport a mass of coastal water approximately the volume of Lake Michigan over 1,000 km offshore into the lower nutrient waters of the northeast Pacific Ocean.^[2] These "warm-core rings" transport heat out to sea, supplying nutrients (particularly nitrate and iron) to nutrient depleted areas of lower productivity. Consequently, primary production in Haida eddies is up to three times higher than in ambient waters, supporting vast phytoplankton-based communities, as well as influencing zooplankton and icthyoplankton community compositions.^[3][4]

The Haida name is derived from the Haida people native to the region, centered on the islands of Haida Gwaii (formerly known as the Queen Charlotte Islands).