Kel Gordon 2014
The End Game
Kel Gordon's new sci fi adventure
Huge Pacific Oysters Sold in Singapore for $4 each.
OVERVIEW
Recently I was asked to have a look at an oyster farming venture in NSW. After nearly thirty years away from oyster farming I was surprised by the lack of technical change considering the oyster research expenditure for NSW.
However what seemed most remarkable was the current lack of understanding in oyster culture biology. Yes, breeding technology is world class but that is where it stops.
And this begs the question.
How can an industry remain viable if simple culture parameters are poorly understood?
Previously Aquafarmer Australia has made comment on existing oyster culture as being 'culture in a survival zone' and not in anyway enhancing oyster aquaculture. Therefore, NSW oyster farming must be looked upon as simply oyster ranching at best. That fact needs to change.
The recent devastating mortality of Pacific Oysters in Port Stephens speaks in volumes about the severe lack of biological understanding and culture requirements for maintaining good health throughout the entire culture cycle.
THE PROBLEM
At a recent oyster farming meeting, to examine the potential of Flupsy Designs, discussions were held to try to understand why or what caused the almost 100% species mortality in Post Stephens.
Flupsy Discussion at Port Stephens
Further to that point, a chance conversation about biological species needs, relative to Pacific Oysters, grown outside their naturally occurring area, revealed that some oysters did indeed survive the so called 100% mortality.
Those oysters were simply held in a completely shaded environment.
THE CAUSE
Indeed yes, the answer as to what caused the Pacific Oyster mortality is simply sunlight exposure.
And to qualify that statement; 'all oysters subjected to long periods of sunlight exposure are very prone to biological stress and death'.
Any visual examination of where wild oysters settle and their associated survival relative to height, flow and sunlight exposure will adequately demonstrate this statement.
Oysters exposed to sunlight will not grow to any size because they are restricted by heat, UV and survival zone exposure. Instead they produce very hard gnarly 'insulating' shells. And then, 'at some random time' they all die off. If one then examines the underside or shaded side of the rock they will find living oysters in 100% of examples. Yes some farmers use shade cloth but it then restricts flow and fouls the trays causing similar mortality potential.
The solution is not modification!
Unfortunately the lease and tray systems used extensively in oyster culture fall into this very dangerous zone of exposure. And it is not surprising that there are major mortality events occurring every few years. Events like QX, Winter Mortality, Summer Mortality and other stress related events where no actual pathogen has ever been definitively diagnosed.
Iterestingly and overlooked by fisheries research is the high survival of oysters below the low tide level. Indeed, there are huge oysters alive and well in all QX and winter mortality culture zones. Environment stress explains this long standing issue.
One of the major problems with oyster leases, in general, is that oysters require flowing water to stimulate growth. However flowing water tends to be low in algae concentrations. So the end result can be that oysters, on an apparent 'good' lease can die of starvation creating yet another question mark.
So it is clear the problem lies in a lack of biological understanding both from an aquatic science perspective and the follow-on into the oyster grower community.
When this commercial education occurs farming methods and farming applications will change very quickly for the better.
Remember, culture control over stick, bag, tray, deep water, floating cage, dredge bed and tumbling devices is still ranching and is not based on biological requirements of species. That has to change.
As a general husbandry rule, in all animal farming world-wide, any stress event will, without exception, always lead to disease and mortality. And oyster lease-culture is a zone of continual inter-tidal stress.
THE SOLUTION
The solution lies in creating an oyster culture method for taking the outdated ranching style culture to a form of actual aquaculture.
In the article on Oyster Nursery Culture there was mention of a new concept design using segmented floating trays reaching 100 meters in length. These trays were submersible for extended culture.
And these 'floating leases' could roll up onto a punt for cleaning and sorting and then roll back into the water. One punt could clean and sort 400 meters of oyster trays per day per man.
The design called for injection moulded trays which could then be submerged for weeks at a time or raised for a few days to kill off fouling thus giving the oyster farmer much more control over second catch, mud worm and at the same time reducing culture time as the oysters grow faster.
But then the oyster farmer would still need to know when worm would strike or when barnacle larvae and D-veliger oyster second catch were present or when the oxygen level was low. This is only the tip of the need-to-know biology of the future successful oyster farmer.
But that was thirty years ago. And there are vast resources able to improve on growth and survival with a standard aquaculture process.
A process greatly increasing control over the entire oyster culture cycle.
And a process for taking the unit number of oysters per worker unit to well over 500,000 per culture cycle.
And that process is simply:
more on this to follow soon
Kel Gordon's new sci fi adventure