A question that we get asked regularly is how to improve the shape of the growing oyster? Of course there’s no fail-safe answer but a system that we have trialled and found to be particularly good is the booster spacer system.
Boosters come in a range of types, the most popular are manufactured by well-known French company YAD Marine. They are designed to slide easily into the bags and hold the shape of the bag open thereby increasing volume. Why is that important?
Benefits of the booster
The puffed-up bag now allows a better through-flow of water and the oysters roll around with the tidal movements because they are not compressed by the weight of the oyster bag. Increased water flow means less silt build-up and creates a ‘cleaner’ environment for the oyster to grow in. The end result is more regular growth and a better shaped oyster.
They come in two distinctive models; the pink model and the black model. The pink model is only available to purchase as a full pallet.
The black booster is moulded and comes as a monoblock. A non-reinforced and reinforced version are available.
The reinforced booster has a bar along either end to increase strength and rigidity. This version is particularly popular in France and would be useful on sites generally that are extremely exposed or have a stronger current.
The non-reinforced version is probably the more popular in Ireland so far. It keeps its shape while still being flexible enough when pulling it in and out of the bags.
Spacers will fit into any standard oyster bags with any size mesh and we’ve seen a positive benefit to growth when used with spat, half-grown and fully-grown oysters.
The pink boosters are made from a mix of polypropylene (the pink sections) and PVC (the grey tubes) while the black tubes are molded reinforced polyethylene. Both types are UV-resistant. Depending on conditions on-site they would be expected to have a lifespan between five and ten years.
How to Use the Boosters
Boosters are most effective when used in bags laid flat in a single layer across the trestle and secured in each corner by a band and hook. In that setup the bag itself is secure and is not moving.
Feedback from growers who overlap their bags on the trestles in order to use less bands is that the movement of the bags themselves encourages the corners of the boosters to rub against the mesh. This friction can ultimately cause wear and tear on the bag over time.
This is not an issue when the bag is secured in each corner, used correctly your old oyster bag and booster spacer will function together in exactly the same way as the casier bag, without your having to invest in new bags.
And because the booster holds the shape of the bag it can stop the corners of the bags from lifting and bending in the wind if your hook become detached thereby avoiding stress points developing on your bag.
Both bag and booster can be re-used repeatedly over a number of years. When not in use, the booster spacers are easily stackable and won’t take up a lot of space in your yard. They can be hosed down to remove biofouling between uses.