THE BONNEY UPWELLING
The Bonney Upwelling – the environment’s gift to Portland.
Spring winds kick off a remarkable time in the waters off the coast of Portland. Through a combination of dynamic environmental events, these waters become the richest marine feeding area in Australia – the Bonney Upwelling.
From November to May, cold nutrient rich water ‘wells up’ from the deep seafloor onto the continental shelf where sunlight converts the nutrients into food for a huge variety of marine animals.
The map is a satellite image showing Sea Surface Temperature (SST) where blue is cold water and red is warm water. The cold plume of the Bonney Upwelling extends from Cape Nelson, near Portland into South Australian waters.
Krill is one of the most important animals in this food web. Many species including schooling fish, barracouta, arrow squid, short-tailed shearwaters, fairy prions, little penguins, fur seals, dolphins and blue whales eat krill.
Fur seals, dolphins, gannets, albatrosses and a variety of sharks feed on schooling fish and squid, and the rain of dead or dying animals from this food web to the seafloor sustains the rock lobster and giant crab populations.
As the Upwelling season progresses, food becomes more and more abundant, with krill swarms becoming larger and denser, and predators becoming more numerous. The Upwelling not only supports this amazing array of life, but also the fishing industry that is so important to our local community.
Although Upwelling extends continuously from western Bass Strait to the Great Australian Bight west of Kangaroo Island, the most intense upwelling occurs from Cape Nelson west to Robe.