NSW Inspires Rare Oyster Delicacy

For almost 20 years David Maidment has been involved in establishing a viable commercial industry for the Native Oyster (Ostrea angasi), and feels that the time may be right for expanding the enterprise.

He produces both Native (or flat) Oysters and Sydney Rock Oysters at the family company, Australian Native Shellfish, based at Wagonga Inlet, near Narooma, NSW. However, it has been the challenge of breeding, growing and promoting the Native Oyster that has maintained his interest in and enthusiasm for the oyster industry.

A baby Native Oyster is a “gorgeous thing”, he says. “You get the shape in them when they’re young and they will keep it. With a deeper, cup-like shell and a round, scallop shape, they really are a good-looking oyster.” The oysters are native to the Wagonga Inlet, where the company is based, although historically NSW didn’t have a commercial industry for the species, unlike Victoria, Tasmania and South Australia. However, the industry in these states collapsed as a result of disease and overfishing in the early 1900s.

David Maidment first became involved with Native Oysters in the early 1990s when he decided to collect a few from the wild, raising them to sell locally. His initial efforts were limited to a dozen or two here and there, but he felt there was greater potential and he headed to Queenscliff in Victoria to review the results of FRDC-funded research done in the 1980s.

Armed with new information, he changed his grow-out systems, trying submerged trays, some deeper water baskets on deeper racks, but still managed to kill plenty of oysters. Trying SEAPA baskets on longlines to control the depth proved to be a better system. This is particularly important when flooding sends a flush of fresh water into the inlet. The oysters can be lowered to deeper water where there is an inversion layer of salt water beneath the fresh water. This is an ongoing issue for operations in the inlet, which has a water catchment of 84 square kilometres.

“The baskets have worked especially well in the estuarine environment and we have expanded this now to 10,000 baskets for both Sydney Rock Oysters and Native Oysters. “You have to grow Native Oysters lower as they don’t like coming out of water as much as other oysters. They are grown at about 100 millimetres to 150 millimetres lower than the Sydney Rock Oysters so they come out at approximately a 0.2-metre tide for probably two hours of sun if the salinity is up, but if it gets extremely hot that’s when they can get into trouble.”

Native Oysters are grown on a two to two-and- a-half-year rotation – one rotation less than Sydney Rock Oysters. The infrastructure required is limited, capital costs are lower and there is a bigger turnover of stock. “This is quite encouraging – that we can sell them and get a good margin. It’s ticking all the right boxes,” David Maidment says.

From developing a grow-out strategy the next step in developing a successful commercial operation was to start breeding the Native Oyster. A group of oyster growers along the south coast collected wild animals and took them to NSW Fisheries at Port Stephens where scientists Mike Heasman and John Deimar were the hatchery managers at the time. The oysters were strip spawned, and the larvae, once set, were reared in upwellers at the south coast farms. “We were getting small quantities through and selling to markets but couldn’t guarantee supply,” David Maidment says. “A couple of us who knew growing Native Oysters was not too complicated decided to breed them to guarantee supplies of spat.”

“NSW Fisheries gave us some background in growing algae and we set up a little micro hatchery with their help. Now we breed all our own stock and we have breeding stock we have selected over six years that we consider the best.” His business is vertically integrated from hatchery to grow-out and marketing. He feels it is nearly time to step up production to meet the growing demand for this unique and rare oyster. And although he refers to his operation as “a little tin-pot set-up”, he now commands $1 an oyster and expects the price to rise with demand.

Today, there are several growers established in strategic locations including Batemans Bay and Pambula, helping to diversify the production base and protect against environmental risks. Last year David Maidment had trouble with algae in Wagonga Inlet. The algae occur naturally but can be toxic in the right conditions. He couldn’t supply oysters for five months. He was a major producer of Native Oysters in Australia at the time and it proved difficult to maintain supplies to restaurants.

“We have slowly developed the marketing. Initially we went to the wholesalers who deal with the Sydney Rock Oyster, but they didn’t know how to handle the Native Oyster, which doesn’t keep as long. We changed tack and have an agent (Steve Feletti of Moonlight Flat Oysters) who deals with the top end of the market. We go direct to restaurants and we get a premium price for the oysters because they are rare. And the market is growing. We have interest from some of the best restaurants in Melbourne, Sydney and Canberra.

“The future is looking quite promising, so we are expanding – we probably have about a million Native Oysters out there now.” David Maidment is quick to point out that many people have contributed to the growing success of the Native Oyster industry. He has sought advice from producers and researchers in Victoria, Tasmania and overseas, with visits to Sweden, Norway, France, the UK, Ireland, New Zealand and Canada.

“Maybe I’ve sacrificed a bit of money at first doing this, but that’s my choice. I can see benefits in this because I can see a bigger world picture now in how rare these shellfish are. “If we could reintroduce these animals into the environment and do it successfully on a commercial basis, I would have achieved something very worthwhile in shellfish farming and I think it is possible. I think with the growing techniques we now have available we can do it. Sometimes it is just timing.” David Maidment says.

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Scientists crunch numbers on food-chain kings

Sustainable shark fishing is about more than just guaranteeing supply of a family favourite to the local fish and chip shop. It is also about maintaining the intricacies of Australia’s marine ecosystem by protecting the kings of the food chain.

The vulnerability of sharks is in their biology: they grow slowly, mature late and produce far fewer young than finfish do. These traits mean that the ability of sharks to repopulate following a disturbance can be low.

“The theory behind a sustainable shark fishery is to catch them when they’re young and juvenile,” says Andrew Tobin, a senior research fellow from the Fishing and Fisheries Research Centre at James Cook University (JCU).

“Take a known proportion out and leave enough to grow up as breeding stock and replenish the fished population.”

Andrew Tobin’s FRDC-funded project aims to measure whether the current levels of shark fishing in Queensland waters – currently capped at 600 tonnes a year – will ensure sustainability of the many local shark species currently being captured.

The project combines previous research on shark biology with tagging of more than 4000 sharks. The goal is to determine the capacity of each species to replenish itself, and to estimate rates of mortality due to fishing. Partners in the FRDC project are the Great Barrier Reef Marine Park Authority, Fisheries Queensland and the Queensland Seafood Industry Association. Meanwhile, the East Coast Inshore Finfish Fishery (ECIFF) is providing practical assistance for the study and insight into commercial shark fishing.

“We have now determined the biology of most tropical shark species,” Andrew Tobin says. “There are growth bands in a shark’s vertebrae, just like rings in a tree. That’s how we determine things like maximum age, growth rate and age at maturity. We have also collected information on pupping frequency and litter size.”

In the earlier JCU shark biology research, each species captured in the fishery was assigned a position on a shark productivity index. For example, the Milk Shark matures a year after birth and reproduces for the next five or six years until its death. It has a high productivity index, denoting a high capacity to withstand fishing.

In comparison, a species like the Bull Shark is much less productive, with slower growth, later maturity and fewer pups from less frequent pupping events. Therefore, the Bull Shark is less able to replace itself following disturbance and should be less intensively fished. Fortunately, this is the current trend at ECIFF.

Even sharks with low productivity can be fished, but more information is needed about shark numbers off the coast of Queensland. During the next 18 months Andrew Tobin and volunteer commercial fishers aim to tag a total of 3000 sharks. Undergraduate and postgraduate students from JCU have already tagged about 1200 sharks in the Townsville area.

In the year after tagging is completed, the fishery will monitor the proportion of tagged sharks it recaptures. For example, if one in 10 captured sharks has a tag, this indicates the fishery is harvesting 10 per cent of the population each year. Some of the more productive species captured by the fishery may be able to sustain an annual harvest rate of 30 to 40 per cent.

When it comes to managing a sustainable shark fishery, Andrew Tobin says sharks have one big advantage over finfish – the stability of their cycle.

Finfish recruitment can be highly variable from year to year, based on water temperature, salinity, currents and food fluctuations. In comparison, shark recruitment is much more stable from year to year.

By late 2012 the research team expects to have a better idea of shark numbers and their resilience to fishing. The work provides a neat bookend to Andrew Tobin’s former role as a member of the ECIFF Management Advisory Committee and part of the discussion about setting a quota for shark fishing.

“It was a tough but understandable outcome when the quota for the fishery was set,” he says. “It frustrated a lot of people in the industry at the time, but there was no data you could point to in order to say ‘This is proof that this fishery is being managed for long-term sustainability’. That’s what this project is about, determining all of those relevant pieces of information and fitting them into the puzzle.”

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