The Stehr Group’s hatchery operates at Arno Bay, a sparsely populated town 115 kilometres north of Port Lincoln. In warehouses also containing state-of-the-art laboratories, mulloway and yellowtail kingfish are reared from larvae to young fish, and continue their development in pens of filtered ocean water similar to the ones that will house them later in the open water.
Morten Deichmann completed his biology degree in his native Denmark before embarking on a career path that has taken him around the world. Deichmann worked on Cyprus, in Italy, Bangkok and regional Thailand before arriving in Australia in 2003. He now engineers the management of all the fish at the hatchery – from spawning right through to their departure for the sea pens.
Through artifical light and controlled water temperatures the fish are encouraged to think it’s the spawning season, and they spawn for longer. Fertilised eggs are then collected from the spawning tanks and placed in incubation tanks, where they hatch into larvae four or five millimetres in length. These larvae are fed rotifers – tiny zooplankton which themselves feed on cultivated algae grown at the hatchery by a marine biologist. Plastic vats at the hatchery hold thousands of litres of the algae, which bubble a brilliant green.
The larvae progress to artemia – commonly known as brine shrimp or sea monkeys. These shrimp grow to between 10 and 15 millimetres in length and are also cultivated at the hatchery. After a month of feeding, the larvae are weaned onto a more solid diet of fish meal pellets, which speed their growth, for a further month. At this stage, the fish weigh about five grams, are about 10 centimetres long, and are ready to be transferred to sea pens to reach maturity. This is a process of at least two years as the fish grow in their ocean homes. The water locations are selected for their rich oxygen content and clear currents.