Tuesday, July 28, 2015

28/07/2015: Cobia: The next big thing? Australia

First published in International Aquafeed, May-June 2015

In Australia, cobia (previously known as black kingfish) are not often seen in the fish markets but are a prized species for tropical recreational fishermen. They generally can be encountered near reefs and other structures from south-western West Australia, around the north of the country and as far south as the central coast of New South Wales. In the wild they can grow to well over 45-50 kg and are strong fighters.

Information was filtering through to Australia from various studies on the species. The information was exciting. The news was that cobia was a very fast growing species - the maximum age recorded for a 1.6m, 50kg+ cobia in the Gulf of Mexico was only 11 years of age. Juveniles grew to more than 60cm in their first year, and fish a metre long were only around three years old. Females matured in their second year when around 80 to 90cm, while male fish often matured in their first year.
Scientists discovered that cobia spawned between April and September in the northern hemisphere (that region's spring and summer) and in Australia the spawning period occurred September to June. The size at first maturity for 50 percent of male and female cobia in Australia was 78cm, again at about two years of age. Additionally, cobia produce excessive numbers of eggs.

Scientists working in the Gulf of Mexico highlighted that individual cobia spawned a number of times throughout the season. Evidence was that the fish spawned as often as once every five to 12 days. It was not unusual to see larger fish spawning up to 1.5 million eggs per batch, but the average 'batch fecundity' of cobia in Australia was shown to be even higher, at 2.8 million eggs per spawning cycle, with the spawning frequency assessed to be around seven to eight days.

Due to their high energy needs associated with their fast growth, they were not considered prissy feeders. In the wild, dietary studies showed that they are bottom feeders, seemingly enjoying crustaceans, especially crabs. 

The Australian Seafood Cooperative Research Centre (CRC) created a project on cobia, which aimed to build on previous research by Queensland aquaculture producer Pacific Reef Fisheries and the Department for Employment, Economic Development and Innovation (DEEDI).

During this research they discovered that the financial potential for fish farmers is very significant, primarily because cobia can grow up to 10 kilograms within their first year - this is double the speed of barramundi and triple the speed of Atlantic salmon.

Although cobia are not fussy eaters in the wild, things are not the same in captivity, and it was important, just like with any new farmed species, to ensure the diet mix is right.

Other problems thwarted Pacific Reef in the early days. Heavy stock losses due to bird predation caused some angst but this was resolved by installing anti-predator cages for the fish to live in as fingerlings. Additional issues were created as the fish were being grown in prawn ponds, which was not ideal due to their shallow depth.

The CRC work also planned on developing reliable and robust controlled spawning methods for cobia, utilising hormonal, social and/or environmental manipulation; production of sufficient fingerlings to enable the on-grow commercial quantities of cobia for market; developing pilot scale cobia fingerling production by the hatchery; formulating diets designed to meet the specific nutritional and energetic requirements of cobia and developing and field testing new farmed cobia product(s) with high market acceptance.

Pacific Reef have shown they have the technical capability and infrastructure to produce cobia for the marketplace and to target the appropriate market sector (high end restaurants and sashimi) for the product. Recently the company won accolades at the 2015 Sydney Royal Show Fine Food – Aquaculture Awards, taking the awards for Champion Fresh Fish (Classes 7 and 8) Sashimi Grade cobia.

 “We want to be Australia’s biggest and largest aquaculture facility growing sustainable product for the Australian and the overseas market,” said Maria Mitris, Operations Manager of her family’s business, Pacific Reef Fisheries.

The company, family-owned and funded, is able to control all aspects of their operation from the high tech hatchery at Guthalungra to the farming operation at Ayr. Their main business is the production of approximately 700 tonnes of black tiger prawns per annum.

Read the magazine HERE.

The Aquaculturists
This blog is maintained by The Aquaculturists staff and is supported by the
magazine International Aquafeed which is published by
Perendale Publishers Ltd

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