The FLUPSY infrastructure set to support WA’s shellfish aquaculture industry

In a trial that aims to boost shellfish aquaculture in Western Australia, the Department of Primary Industries and Regional Development (DPIRD) installed one of Australia’s first large-scale Floating Upweller Systems (FLUPSY) at Albany’s Oyster Harbour. Utilising a pump to push seawater through mesh pots allowing the seed to feed on phytoplankton, FLUPSY offers a sustainable and efficient nursery environment which allows for high stocking densities of oysters. Pump Industry spoke to Scott Bennett, Aquaculture Systems Co-ordinator at DPIRD, to find out more about the trial and the pump used to help grow oysters.

What is a FLUPSY?

A FLUPSY is a mechanical system designed for the culture of seed stock during the nursery stage of commercial bivalve production. They are mobile and cheaper than more traditional land-based methods and are often used for oyster culture in the US, mainly in homemade structures made from timber and plastic drums.

“Traditional upweller systems are housed in a building very close to a seawater source, requiring considerable equipment, infrastructure and coastal land, making them both capital and energy expensive,” Mr Bennett said.

“Such systems pump water up through an array of ‘pots’ held within a large flat tank that are screened on the bottom to hold the spat. Some land-based systems pump seawater from ocean intakes which provides the algae that the spat feed on.

Other systems require the algae to be cultured in a laboratory and added to the seawater. Upwellers thus provide feed to the spat as well as have their excrement removed with the upwelling water current.

“A FLUPSY is an alternative way to upwell oyster spat where all infrastructure can be installed on a floating pontoon in protected waterways, utilising the water and feed naturally occurring in the area.

“It is a more affordable and sustainable form of shellfish nursery culture, taking advantage of the natural environmental conditions.” The DPIRD FLUPSY was designed to hold 30 square pots with the capacity to hold up to 250,000 oyster spat in each.

These pots have a screen attached to the base to prevent the oysters from falling through but allowing water to upwell past. “In the centre of the FLUPSY there is a long gutter which has 30 pipes attached to it and a large shroud on the base at one end where a pump is installed to constantly push water out of the gutter,” Mr Bennett said.

“The gutter would sit so all 30 pipes were just below the water surface. Each of the 30 square pots have a hole on the side which would slide tightly over the gutter pipes, locking them in place.

As water is pushed out of the gutter by the pump, new water would be drawn in up through the pots, into the pipe and into the gutter to be pushed out of the gutter by the pump.

“This pot and gutter system was installed with a floating pontoon around it, allowing it to be walked around for servicing and supporting all the FLUPSY components.”

Trialling the technology at the Albany Oyster Harbour

Mr Bennett said the FLUPSY concept was first raised at an oyster workshop in Broome in February 2019. “Jonathan Bilton, a well-known shellfish hatchery operator, mentioned FLUPSYs to Greg Jenkins, the Director of Aquaculture Research and Development for DPIRD, “Mr Bennett said.

“Greg saw potential in the system for use in Western Australia and sought funding from the Minister of Fisheries to design and build a FLUPSY for testing with a local species of oyster.”

The FLUPSY was designed, constructed, and supplied in 2021/22 by DPIRD to Harvest Road Oceans (HRO) for commercial trial undertaken at its farm site at Emu Point, Albany and was supported by DPIRD’s aquaculture research and development team, with rock oyster spat (Saccostrea glomerata) supplied by the Albany Shellfish Hatchery.

The WA-based FLUPSY design and development was led by one of the shellfish R&D teams. The trial was supported by $125,000 through the WA Recovery Plan and saw one of the first large-scale FLUPSYs in Australia installed, with a production capacity estimated at 5-10 million 5mm rock oyster seed per year.”

Mr Bennett said there were a number of considerations that needed to be taken into account during the design and development phase as the only component that was available off the shelf was the pump.

“The pontoon and other components all required custom fabrication so significant time was spent designing the system so each fabricator could be provided with accurate specifications. Local West Australian fabricators were used to build all the components.

This ensured easy communication and the ability for site visits to check on progress and measurements throughout the build,” Mr Bennett said.

“The FLUPSY needed to be able to fit into a 10m x 4m boat pen, be lightweight, strong, and built-in sections so it could be easily transportable. The pontoon was designed so it could be split into six smaller sections and the gutter could be split into three sections allowing the entire system to be transported on a flatbed truck.

“Buoyancy had to be perfect, so the system did not float too high too or low in the water. Flotation pods could be moved around the pontoon, added, or removed as required. As the project commenced and more weight was added to the FLUPSY, extra floatation was easily installed.”

The operational implications and spat performance in the FLUPSY were the two main factors being considered in the early trial, with the data gathered giving a starting point for the determination of more focused and detailed work to determine more accurate and definitive operational parameters for the FLUPSY.

The pump keeping the water current moving

The FLUPSY required a pump that could reliably operate 24/7 in a harsh saltwater environment where the possibility of entanglement with seaweed was high. There was little need for the delivery of high head but there was the need for a high flow rate.

“The aim was to draw 20lpm through each pot containing oysters, the more water we could move the more food that could be drawn through the oyster through the upwelling process,” Mr Bennett said.

“A variable speed pump would also be of advantage as this would allow the adjustment of water flow depending on the number of oyster spat being cultured in the FLUPSY.

“There are FLUPSY systems in the USA operating on a de-icing pump which mo ves a significant amount of water to prevent ice from forming in saltwater marinas. A company called Bearon Aquatics in the USA had a vari-speed axial flow pump which suited the requirement for our FLUPSY.

The pump can push a huge amount of water which allows a large volume of water to be drawn through each of the FLUPSY’s pots containing oyster spat. This would ensure they received the most amount of feed and clean water possible, resulting in optimal growth and condition.

“The DPIRD FLUPSY is currently powered from 240v shore power; however, if required the pump used could operate on a photovoltaic power system.”

The pump’s specifications for the Bearon Aquatics P1000 vari-speed Ice Eater are:

• Power – 240v, 750W, 3.2A at 100 per cent operation
• Maximum flow rate – 36lbs of Thrust at 5,200Lpm/312,000Lph
• Weight – 20kg
• Size – 200mm diameter x 350mm high

Observations of the day-to-day operational performance of the pump

Stocking capacity is in part a function of water flow through the upwellers. The pump evacuated the gutter and gravity drove the flow of water through the upwellers. Increasing the pump speed caused the buoyant gutter to raise the FLUPSY out of the water and stop the flow. The pump speed needed to be balanced against the weight to maintain a consistent flow of water through the upwellers.

Resetting the pump speed and checking valve settings were completed each day. A maximum water flow of ten to 15L per minute was recorded through each pot. With 16 of the 30 upwellers in operation, the pump was set at 60 per cent. With 30 upwellers in operation the pump can be set at 100 per cent.

Maintaining the Ice Eater pump and other equipment

Mr Bennett said the Ice Eater pump has proven to be very low maintenance. “There are two sacrificial anodes installed on the pump. One is on the pump’s housing, the second is on the shaft. Both have been checked for deterioration monthly and have been replaced every six months, which is a quick and easy process.

The propeller is also replaceable however it has not required replacement after ten months of operation,” Mr Bennett said. “General cleaning on the FLUPSY can be carried out with the system in the water using a broom and hose to remove fouling and unwanted growth.

The pots are lifted onto the pontoon and the oysters are sprayed with a hose to wash out any faeces. Divers check the pump’s anodes for corrosion and can clean the underside of the gutter to remove any excess fouling.

“Every six months all the 30 pots containing oysters can be removed from the FLUPSY and the entire system can be removed from the water using a large boat trailer. This allows a thorough check of the system for damage or wear and the removal of heavier fouling such as barnacles in hard-to- reach places.”

Corrosion was an issue on other components of the FLUPSY – the bolts, nuts and washers mounting the screens onto the upwellers and the protective metal screen on the bottom of the upwellers all showed signs of corrosion. This impacted the nylon mesh that supported the oysters and could lead to a breach of the screens.

Results of the trial

Mr Bennett said the trial FLUPSY has performed very well, and excellent results were seen in the oysters cultured in the system during the initial trial. The final report on the trial – which Harvest Road Oceans funded and provided resources – found the compact size of the floating sea-based nursery allowed for high stocking densities of oysters that could be held in it, providing a major benefit compared to traditional systems.

Observations were made during the trial that will help improve their design and operations in Western Australia and it also provided a baseline for further and more detailed work.

One observation was the safety risk posed to workers during manual handling, specifically lifting of the upwellers from the water onto the deck of the FLUPSY which involved lifting the upwellers from floor level and raising them out of the water at approximately 200mm away from the worker’s centre of gravity up to waist height then twisting to move the pot onto the deck.

The upwellers weigh 13kg dry plus several kilograms of oysters and the weight of the water that is retained – this can reach a total of approximately 40kg. “The pots, once full of oysters, became heavy and a hazard to lift safely so a lightweight gantry was designed and installed on the pontoon.

The gantry is tracked so I can roll up and down the pontoon, allowing the pots to be quickly and safely lifted for cleaning, saving significant time and eliminating the manual handling hazard,” Mr Bennett said.

Another observation during the trial was that the FLUPSY was quite sensitive to weight distribution. Keeping the FLUPSY low in the water is important to maintain water flow through the upwellers, however, this leads to a situation where the FLUPSY sinks during cleaning when the upwellers are out of the water and up on the walkway.

 

 

 

“The pontoon at times sank a bit low in the water when there were extra personnel onboard for servicing so the spacing of the floatation under the pontoon was adjusted to improve its stability. “A second pontoon has since been constructed which allows the flotation pods to be installed on a different angle, giving it more stability without affecting the overall buoyancy of the pontoon,” Mr Bennett said.

Other recommendations for potential modification noted included:

• Offset the upweller pipes so that flow from one is not directed into another
• Make the upweller flange internal instead of external to allow for easier handling of the upwellers and prevent them catching between the rail and the gutter
• Add a lock box to the FLUPSY for storage of tools, lubricants etc.
• Reduce the height and weight of the upwellers
• Change the wing nuts, that secure the upwellers, to a quick release clip to prevent them rattling loose
• Build a jinker to transport the FLUPSY and allow for easy launch and retrieve

The work undertaken in this trial is preliminary and provides a baseline for further and more detailed work.

More work is required to improve the mechanical aspects of the FLUPSY, such as floatation, buoyancy, and stability; improved access and egress; determine the suitability for other locations with different environmental conditions; and investigate options for operation of the FLUPSY remotely from mains power.

Further trials are required to better define bivalve performance in the FLUPSY, such as carrying capacity and growth performance of oyster spat in various environmental conditions; refine stocking density and response of various sizes to density and the relationship between flow rate and density.

The future of FLUPSY is Western Australia

DPIRD has plans to install a second FLUPSY system in protected waters of the Perth metropolitan coastline to trial its suitability for Saucer Scallop culture. This system will require further design and fabrication and is expected to commence mid-2023.

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