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Victorian growers hatch mussel SURVIVOR PLAN ictoria is close to regaining its position as the leading producer of mussels in Australia after recovering from a production decline that reduced output by as much as 80 percent. The recovery has been led by a grower-government collaboration to establish a hatchery at Queenscliff, which is now creating opportunities to expand into the production of other shellfish. Port Phillip Bay has traditionally been the heart of Victoria's mussel industry, and the largest producer in the bay is Sea Bounty, operated by Lance Wiffen and based at Portarlington. Mussel production boomed during the 1990s, when Lance Wiffen was one of 21 licensed operators in Port Phillip Bay and Western Port. Driven largely by production in the bay,Victoria's harvest increased fourfold during the decade, from 300 tonnes in 1990-91 to 1582 tonnes in 2001-02.Then began the decline. Sea Bounty's harvest plummeted from a peak of more than 1000 tonnes to only 200 tonnes in 2007-08. While the business struggled on, many other growers walked away from their leases. Today, only a handful of operators remain in the bay. PHOTO CREDIT: BRAD COLLIS BY CATHERINE NORWOOD V UNCERTAIN CAUSE Victorian Department of Primary Industries aquaculture officer John Mercer says that despite considerable effort from both industry and government between 2004 and 2006, no definitive cause was found for the decline in mussel spat. It was eventually attributed to the influence of extended drought. The reduction in natural inflows into the bay resulted in fewer nutrients in the water for the algae that the mussels feed on, and salinity levels also increased. Research during this time trialled a number of different methods to improve the capture of wild spat. This included the inversion of the traditional longline. The inverted system places the longline closer to the waterline, attached to the buoys, with the dropper ropes hanging down from the longline, which several operators have now adopted. GROWING THEIR OWN With natural production uncertain and the cause unknown, farmers attempted to source hatchery-produced spat. When this proved unsuccessful, a group of farmers led by three growers, Lance Wiffen, Peter Bold (Advanced Mussels) and Peter Lillie (Bay Sea Farms) entered collaborative agreement with the Victorian DPI to "develop a recipe" to grow their own mussels. It took a year to get the $1.3 million Victorian Shellfish Hatchery agreement in place and to build the hatchery at the Victorian DPI's Queenscliff research centre before production could begin in 2008. Spat production failed that first year. A workshop involving Australian and international aquaculture experts, including those from the oyster and pearl and mussel industries came together to review the hatchery's operations and identify possible causes for the failure. Among the most likely problems identified were the "newness" of the hatchery facility – the residues remaining from construction – temperature and handling shocks and the algae feed supply for the larval spat. The second spawning at the hatchery was a success and the farmers were able to set out seeded ropes to secure their Whiteworm tracks visible on mussel shells production for the following year. Now in its fifth year of operation, the hatchery currently does four to five spawning runs a season. Each run produces 1200 ropes, each seeded with between 50,000 and 70,000 mussels per rope. The hatchery project has reached the second stage of development and is now a purely private joint venture for the three commercial operators, who lease the facility from the Victorian DPI. However, biofouling is an ongoing issue for mussel growers in Port Phillip Bay and Lance Wiffen has been involved in research to come up with methods for controlling two major pests: whiteworm and hydroids. Whiteworms are a coral worm, and while they do not affect the meat of the mussel, they do damage the shell leaving tracks which can be hard to clean. Hydroids are marine animals that look more like plants and both local and introduced species are found on the mussel lines in Port Phillip Bay. "The problem is not so much the hydroids themselves, but the ascidians – sea squirts – and Pacific starfish that come with them," Lance Wiffen says. Apart from fouling the mussel lines, the starfish predate the young mussel spat, the wild spat more so than the hatchery spat, Lance says. During the 2011–12 season, Lance commissioned some trials to come up with management options, testing both freezing and hot water techniques. While freezing killed the pests, it also killed the mussels. However, a hot water wash proved successful in the trials, and he has developed a commercial boiler that can be fitted onto his fishing vessels.The water is heated to around 80 degrees Celsius on board and mussel ropes are drawn through a wash held at around 50 degrees Celsius. Lance says that when he does begin to incorporate the hot water wash into his operations he will need to do site specific trials to find the right temperature to balance mussel survival and pest control, taking into account the age and size of the mussels and the time of year. The research was supported with some FRDC funding and further research into the control of hydroids is being undertaken at the University of Melbourne. An excerpt from an article published in FISH magazine Vol. 21 No.1 MAY/JUNE 2013 ■ NZ AQUACULTURE ■ 13