Multi-Species Marine Traps
Used Aquaculture & Processing Machinery
Fukui's Monthly News Letter
What's up? FLUPSYs
In other articles I have briefly discussed FLUPSYs and their value in the culture of certain shellfish species. To understand its effectiveness for shellfish grow-out, especially the nursery stage, the principle of welling should first be explained. A weller is a containment area that is designed to allow regulated fluids to pass through. The passing fluids have a controllable effect on whatever material is in the containment area.
There are two types of commonly used wellers: downwellers and upwellers. Downwellers allow fluids to pass down through the containment area, over the material that is being affected. The fluids then exit through a holding device or material at the bottom. In the case of shellfish seed an appropriately sized mesh screen is used.
One of the simplest and most common downwellers, used daily in most households and restaurants, is the coffee maker. Hot water (fluid) is allowed to pass over ground coffee (material), and exits through the filter (mesh screen) at the bottom of the filter basket (containment area) to produce brewed coffee.
Upwellers are simply the reverse of the process. Fluid is passed first up through the mesh screening and the material being effected. It then exits through the outlet at the top of the containment area.
The reason shellfish aquaculturists use welling is to provide an intensive controlled nursery system that force-feeds nutrient-rich water to the infant shellfish. That allows them to grow more quickly, have a higher survival rate, and conditions them to be always in a "want to eat" mode. In general, enhancing the grow-out abilities of shellfish reduces the time needed by the animals to reach market size - and that is a benefit to the grower's business.
The decision on which type of weller to use is a function of species, available equipment, site location and design.
Upwelling will allow a more even flow of nutrients though the shellfish seed and is commonly used for nursery systems. Usually seed size, depending on species, should be at least 1.5 mm. to 3 mm. If smaller seed is used it may become fluidized and escape through the top of the upweller. The solution then is to use a downweller. In other words, downwellers are often used in primary nursery applications to prevent the escape of the smaller seed.
Over the years, I've seen welling action created by a variety of applications and designs. Most have been tank systems, both indoor and outdoors, depending on climate and other conditions.
As an example, one welling system used for clams was set up like a raceway. It was designed as a long flat tray that had an elevated exit pipe at one end. The opposite end had induced above-surface water injection to enhance oxygenation in the water. Mud and silt settled at the bottom of the tray, just the kind of environment needed by the clams, so the system worked well for that species.
FLUPSYs have several advantages over tank-based systems in that they can:
1. Generally handle high volumes of product;
2. Be moved to selected nutrient-rich sites dependent on the time of year, and;
3. Be located closer to, or at, the grow-out sites.
Since in many ways shellfish aquaculture is still in its infancy, experimentation continues to be done on the design and construction of upwellers. The general trend has been to produce smaller systems as cheaply as possible, using whatever materials can be found locally. While that approach may be OK for experimentation, it is unlikely to provide the volumes needed by commercial operation.
In some of my other articles, I have stated that the rules of aquaculture gear are:
1. it has to last as long as possible (buy the best or most advanced);
2. labour has to remain constant or decrease, and;
3. yield has to remain constant or increase.
A FLUPSY must be designed with those rules in mind to be commercially effective, though the vast majority of working applications I have seen do not meet the criteria.
To show how commercialization can be achieved, I explain the workings of an existing commercial FLUPSY in Commercial FLUPSY - It Works. This FLUPSY can process 10 million seed per year with only two people - now that fits within the rules for aquaculture gear.
Contact Don Bishop at:
Fukui North America
110-B Bonnechere St.W.
Eganville, Ontario K0J 1T0
Email: firstname.lastname@example.org or email@example.com
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