O angasi ( Native Flat Oyster) Update

Up-Weller Tank With Angasi

Up-Weller Tank With Angasi

Baby Flat Oysters 4-8mm

Baby Flat Oysters 4-8mm

It has been a while since I have mentioned much about the native angasi oyster. At present we have a  new crop of young angasi’s in our land based up-weller tanks, growing them from less than 1 mm to over 4 mm so we can put them out onto our leases in the Inlet. They are growing well with the first batch being put out this week.

We have large numbers of flats coming through for sale with one of our leases nearer the ocean entrance producing a slightly smaller oyster with  a distinct lingering flavor, that I find  really tasty. I think oyster lovers will find these particulary nice.

It is interesting to observe that we have been growing and breeding flat oysters for more than 15 years and overall they are doing well.  We have had some mortalities and this has been been due to our lack of knowledge in handling them correctly.  In other places around the world they have proved difficult to grow and breed, and suffered from a disease called bonamia.  We have a strain of this disease but our management seems to minimize its affect.

Interest is growing and other shellfish producing area in Australia and around the world are experimenting in growing them to diversify their income base and hedge against diseases that could affect their Pacific Oyster Industry.  Victorian Mussel Growers are 2 years into their trials and the angasi’s seem to be growing well on their deep water mussel leases in Port Phillip Bay. They source their young stock from their Queenscliff Hatchery which produces mussles and scallops. Interest is also being shown in South Australia where they also occur naturally.

Overseas interest has also occurred.  Skip Bennett from Island Creek Shellfish near Boston on the east coast of the USA paid us a visit last year. As far as I know he bred some O.edulis in his own hatchery this last summer and I will be interested to hear from him about how they are going. Brian Kingzett from the Deepwater Shellfish Research Centre at Nanimo Canada also came down with a view to breeding their wonderful O.olympia and using it restock shorelines. This small oyster is very rare now and once was the mainstay of the shellfish Industry along west coast of USA and Canada. A very good read, if you can find it is a small book called the Living Shore by Rowan Jacobsen describing the discovery of the last remaining population of wild Olympia oysters on a remote shoreline on Vancouver Island.  New Zealand  is working on breeding and growing O.chilenus the famous Bluff Oyster a slightly different oyster to ours and we have done some work with in Sweden on O edulis and it would be good to do some more with British and French oyster farmers to see if some of our techniques used here in Australia might help improve their flat oyster production.

I suppose the reason behind all this is the Ostera species of oysters are rare and command very good prices therefore commercially they are worthwhile growing.  I think it is also important to re-introduce a species to the marine environment that has been neglected and over harvested in the past and reduced to remnant populations.

PACIFIC OYSTER MORTALITIES IN PORT STEPHENS ?

One of the issues being discussed among oyster farmers is the death of pacific oysters in Port Stephens near Newcastle.  Many farmers have been concerned that it is the POMS virus that has decimated the Pacific Oysters in Georges River, Sydney Harbour and Hawkesbury River.  It has been thought by many people that Port Stephens would be the next harbour to be affected due to the proximity to the above places, ocean currents and the possible transference by boat traffic.

A couple of observations are worthwhile at this stage. Worldwide oyster diseases appear to be species specific. eg QX and Winter Mortality with Sydney Rock Oysters, bonamia with Flat Oysters, and now POMS with Pacific’s.  Transference can occur quickly in sea water held within non affected oysters eg. Sydney Rocks could transfer the  POMS virus and consequently trans-location policies are in place  ( monitored by NSW Fisheries)  and growers are careful when moving stock and need Fishery’s Permits.

Evidently, 1200 tests have been done on both cultured and wild Pacific’s in Port Stephens and no known disease has been detected.  This was reported to growers in Port Stephens at a meeting held last week.  The question remains what killed the oysters?   Are the animals under stress from some other factor?   Observations expressed by growers and fisheries were that water temperatures in November when deaths were first noticed were quite high , rainfall runoff from the land can carry contaminants which could kill oysters but remember Flat and Sydney Rocks Oysters didn’t die and some algal species could be ingested solely by Pacific’s could be toxic. Another consideration is that Pacfics could be nearing the upper latitude for there growing range.   Originally they came from a cold water environment in Japan and Korea.   So it could be a stress related issue where the oyster becomes vulnerable in this warmer temperate marine environment and dies from some physical factor.   Evidently increased mortalities are also occurring in Pacific’s in France due to  a Vibro bacteria related issue.   This has not been observed here.

The mystery continues and worries growers not only in NSW but Tasmania and South Australia.  Growers have been advised that a POMS resistant oyster will not be available for at least 5 to 8 years therefore will not help Port Stephens oyster farmers at the moment.

2014- Beginning of the Oyster Breeding Cycle

Oyster catching slats

Oyster catching slats

Happy New Year to everybody. I have had a small break from writing due to a busy festive season both on the farm and with the family.  It was great to catch up with all the family in Melbourne and not only did we have lovely oysters for Christmas Dinner but we delivered many thousands of dozens to Sydney and Melbourne as well as a large quantity of Flat Oysters (angasi’s) to Victoria.

Narooma has been busy with glorious weather and very fine oysters available due to the drier weather.  The oysters have been in superb condition they are very plump and fat. I think they are some of the best oysters we have had for a number of years.

Most of the farmers have been very busy with their attention turning to preparing our plastic catching material out onto the leases for the coming natural spawning cycle.  This often occurs after the big tides in January and February or when rainfall occurs in the early autumn.  Also the last of remaining material from last year is being brought in and sorted before being put onto the growing leases in Narooma.

Put the the weekend of the 5th and 6th April in your Calendar. The Narooma Oyster Festival has been moved a month froward to take greater advantage of the warmer weather in early April.  Check out the web site naroomaoysterfestival.com.   It is a wonderful weekend with lots of activities and many things of interest.

Christmas On The Oyster Farm

Merry Christmas to all.  It is an excellent time to enjoy beautiful Narooma Rock Oysters fresh from the farm.  The water temperature has risen a degree or two and with the rainfall we had a few weeks ago they have fattened beautifully.  I can’t stop sampling them as we harvest oysters for sale.  The are just delicious.

Demand is excellent with deliveries being made to Sydney markets and beyond.  Growth in our young oyster stock has been good and we are constantly refilling our tray leases as we sell oysters to market.  It is a busy time of year.  

Another surprise is the good condition of the flat oysters (angasi)  As mentioned before they prefer (or so I thought) cooler water temperature but this year they have reproduced in Oct/Nov and refatened now.  Not sure why this has occurred but water temperatures were a little lower for a longer period this spring.  Maybe this was a factor.  We are forever learning.

Check out the recipe a lovely Christmas entree and a favorite of mine.

Tiger Prawns, Seaweed and Rock Oysters

Tiger Prawns, Seaweed and Rock Oysters

Wild Caught Sydney Rock Oyster Seed

I thought it might be interesting to show one method of supplying juvenile oysters to our farm. During the autumn wild oysters spawn up and down the NSW coast when the natural environmental triggers occur. These are water temperature, a drop in salinity caused by rainfall and often very high tides that occur on the full moon. Oyster farmers use this natural phenomena and place catching material on special leases where this larvae is concentrated and on an average year get a good settlement rate. In our case we use the Moruya River and Narooma.

At this time of the year farmers are moving this catching material back to their growing leases for on growing and finishing. At present we are moving plastic slats back to Narooma to strip the seed. We trailer a punt to Moruya and bring back approximately 1000 slats a load which were placed on a rack in the water, at the correct height and on a  frame holding a little over 100 slats.

A frame of slats and small oysters which have been knocked off.

A frame of slats and small oysters which have been knocked off.

 

This year has been a good year with many 100,000’s of oysters settling on our catching material. We pull the frames a part flex the slats and the spat falls into a tub. We water grade the spat and divide it into sizes that will not fall through our different container mesh sizes. At this stage it is important to put the right volume in each container. It is important at this stage to get the oyster shell shaped ( deep and cuppy)  as it will hold that all its life and the meat condition will follow that shape. In two years time we aim to have marketable stock.

In addition to this we use serrated French tubes ( 1.2 metres in length) to catch wild oyster spat and a large quantity of hatchery grown oysters.

Slats with baby oysters (spat)

Slats with baby oysters (spat)

SPRING RAINFALL COMES IN TIME TO SET THE SEASON UP

Monday (11/11/13) saw the South Coast get a welcome rain event. In particular Narooma received over 100mm which is the heaviest rain we have had since last April. The district was quite dry and oyster farmers like land based farmers need some rain but hopefully not  excessive amounts which can cause flood damage.This amount is fine and let me explain why.

The feeding rate of oysters is water temperature dependent. In these southern waters ocean sea temperatures are rising as the East Australian Current pushes down along the coast from the north. Presently water temperatures are approximately 18 degrees and increasing. Combined with rainfall such as we have had nutrient levels increase in the estuaries and rivers encouraging natural microscopic algae and plankton to grow. When it is dry we don’t have so much nutrient input and these organisms are restricted in growth.

So with these conditions oysters and other wild shellfish increase their feeding rate and with the increased availability of food hopefully shellfish will flourish. This takes a few weeks to occur as we need good ocean water exchanges to take place to help promote this natural blooming of microorganisms. It looks promising for the coming festive season and oyster farmers in this region have been filling up their leases with stock for the coming summer and autumn sales.

At present sales are temporarily suspended due to this rainfall. Along with nutrients contaminants can be washed into rivers and estuaries where the oysters are grown. It  takes a week or so for the oysters to flush these out and oyster farmers monitor the water and test the oysters to make sure they are safe for human consumption. All commercial oyster farmers by law have to harvest and sell there oysters under strict protocols laid down by the NSW Food Authority which complies with world standards. This has been in existence for many years and underpins the commercial viability of oyster farming.

This has been a very timely rain event and even though we are closed for commercial sales at the moment, the short term pain will have a much greater long term gain.

MARKETING OF SOUTH COAST OYSTERS

Australia's Oyster Coast

Australia’s Oyster Coast

As briefly mentioned in other blogs our family company (Australian Native Shellfish) is linking with a group of other South Coast Growers to form a Marketing Group under the brand name AUSTRALIA’S OYSTER COAST.

This group launched at the Narooma Oyster Festival has been formalised, has paid up grower members,  a business plan and appointed a CEO Andrew Wales. The aim being to increase the public awareness of the fabulous oysters grown from the Shoalhaven to the Victorian Border. It hopefully will give a focal point for commercial buyers and the general public to source our oysters and give some idea to consumers the unique sustainable modern way our oysters are now grown.

I recommend a visit to the AOC website and check out the draft video. It is a beautiful presentation and gives you a taste of this wonderful region. The young generation of farmers behind this Branding are a credit to the the Industry and it is refreshing to see them want to take this Industry to the next level. The Shire Councils (Shoalhaven, Eurobodalla and Bega) are being very supportive and hopefully will come on board for the development of the AOC Oyster Trail from Shoalhaven River to the Victorian Border.

I feel this is one of the most positive moves made by oyster growers on the South Coast in my 30 years of farming oysters in Narooma. Keep an eye on the AOC web site for new developments