The innovative AquaBait marine worm farm was first featured in the April May 2004 (Vol 18 No 2) edition of Austasia Aquaculture Magazine. Back then the main market for the worms was as live bait for recreational fishermen. Since then R&D has identified the significant nutritional benefits of marine worms and this has led the development of new and lucrative markets for these curious creatures, both here in Australia and overseas.

They key to the new interest is a type of polyunsaturated fatty acid called bromophenol (see box insert) which have been found to significantly improve the nutritional quality and overall taste of cultured seafood. Marine polychaete worms have been found to be a natural source of these bromophenols. With natural supplies of these worms becoming overfished or destroyed by habitat degradation, the search is on for more and more farmed worms.

According to Ladislav (Les) Safarik, AquaBait worms have been reported to have high levels of bromophenols (1.16mg/gm – Whitfield et al 1999). “In addition, due to beneficial HUFAs and PUFAs marine worms form interesting appetizer in larval weaning and broodstock propagation diets,” he said.

Tony Charles, hatchery manager at Mackay-based Australian Prawn Farms swears by them. “We have been feeding frozen AquaBait worms to our broodstock for more than three years. Along with squid and mussels we feed the worms as a certain per centage of their diet. The AquaBait product is both clean and nutritious. They are a fantastic and irreplaceable part of our special balanced diet for our prawns.”

 

The amazing part of this story is that this world’s best technology has been developed not by a big team of scientists but by a Sydney-based family. Les and his family emigrated from Czechoslovakia in 1982 and settled in Sydney. A committed recreational fisherman, he often bemoaned the fact he couldn’t get decent worms from the bait suppliers. Milada, his marine biologist daughter, suggested they have a go at growing them. So they set up a ‘hobby laboratory’ using a recirculating aquaculture system of their own design and there began a 10 year quest to discover the secrets of these fascinating animals.

They chose the tube worm Diopatra as it is found in oceanic waters (up to 30m deep) throughout mainland Australia from Brisbane around the southern coastline to Shark Bay. Also, as it occurs in the lower reaches of estuaries, this species can tolerate fluctuations in both temperature and salinity.

After four years Les and Milada managed to get their worms to spawn. It took them another two years before they got large numbers of larvae settling. Then they knew they were onto something and so they established some gravity flow tanks at the Eraring Energy Power Station, a bit over an hour drive north of Sydney. To their surprise, the worms were not dying; in fact they grew quite well in the variable temperatures and salinities of Lake Macquarie.

It took another three years of struggling with bureaucrats and other ‘non-believers’ before the Safariks obtained a long term lease on land next to the Power Station. This Government owned coal fired power station supplies 40% of NSW’s power. The Safariks now can pump water from the 3m channel that takes cooling water from Lake Macquarie to the power station.

“We were greatly helped by the Hon. Richard Face MP who at the time was Minister for Hunter Development,” said Les. “You can’t imagine how happy we were to be able to build the first eight ponds. The concrete ponds were stocked in 2001 (September) and some 12 months later we harvested our first worms for sale.”

“The ‘big break through’ in our hobby farm was having the worms eat out of our hand,” Milada explained. “We became quickly emotionally involved with them and there were almost tears flowing when the first crop went off to sale to be put on hooks to catch fish.”

Milada had been undertaking a Masters thesis on the worms at Newcastle University (the title of her thesis was ‘Intraspecific density effects on the growth and tube diameter of the polychaete Diopatra aciculata Onuphidae’). She examined spatial relationships between the worm and their tubes and a variety of factors which influenced this. The research was so innovative she was awarded the Rural Women’s award in 2003. At the same time the Safariks successfully applied for a grant from the Department of Agriculture, Forestry and Fisheries’ New Industry Development Program.

“This provoked us to work even harder and we finished the rest of the farm,” said Les. “We now have 3,000m² of area under water, mainly in 2.5m by 10m polyurethane-lined tanks (to conform with local EPA requirement, may not be necessary in other locations). Over the time we have been able to consistently sell live worms and frozen ones for recreational fisherman. We have reduced the production cycle to nine months and can budget on at least 2kg/m². In 2006/07 we harvested more than 6,000 kg, and we are on track to reach our capacity of 10 tonnes in 2007/08 from our 3ha farm.”

Water is continually pumped up 12m from the power station inlet channel with open impeller centrifugal pumps through 225mm underground PVC pipes. To prevent predators (eg. fish or crustaceans) entering the system with the inlet water, a predator exclusion cage is placed in front of the pump station where the suction pipe is held.

Valves direct the water into 150mm branch lines which in turn supplies each tank through a 50mm inlet pipe, these are also controlled by a gate valve. Spill sheets made from thick plastic are on the inlets to reduce erosion of sediment layer. The 25m² tanks are in rows of three and there are now 96 in use.

 

Beach sand high in silica purchased from legitimate sources is used to form the sediment in the tanks. There needs to be sufficient space for the worms to burrow and form their tubes. The tubes are made from a matrix of complex carbohydrates which extends to the bottom of the hole. The top can protrude 2-3cm out of the sediment. These worms are very good at camouflaging their tubes and they will collect shells, small stones and other matter to harden the tops. Milada said that the tube will biodegrade within four weeks if the worm dies or leaves it.

The sediment is one complicated bio-system of bacteria, worms and other microbes so the BOD (Biological Oxygen Demand) is high. The worms undertake bio-turbation where by their burrowing behaviour they move sediments from the bottom of the tank. Thus, the whole sediment is continually turned over to the top layer and allowing oxygen to get down to these bottom sediments.

Stand pipe risers on the 150mm outlets allow the water level to be determined, but generally around 5-10cm above the sediment is sufficient. These risers can be heightened if water quality conditions are threatened in Lake Macquarie, eg. significant rainfall in the catchment.

This proved to be very useful in 2002, when the nearby Dora Creek flooded and there was a freshwater layer in Lake Macquarie for 2-3 days around the surface pump for inlet channel. The water depth in the tanks was increased before the flooding and then the water turned off until the salinity increased. Aeration can be added through a pump driven venturi to the tanks if they can’t do the normal tank exchange of once every 3 hours. The worms are OK with no feeding for several days.

According to Milada, the Diopatra worms are very efficient at oxygen exchange. “They have large surface area of gills around their heads, also they have gaseous exchange surfaces on each segment near their setae (hairs or spines used for moving). At low tide they may sit in their tubes of stagnant water for 3-4 hours They can lower their metabolism to cope with low dissolved oxygen levels.”

However, stress from being out of their environment doesn’t help for long travel times. “Our live worms are OK if they are transported in their tubes but only if the travel time doesn’t exceed 24hrs.”

 

Diopatra are broadcast spawners with fertilisation in the water column. If the cues are right (food and water temperature) they will spawn repeatedly above 16^oC. Milada said that they are highly fecund but in nature there is huge juvenile mortality by predation. “Just about anything that can catch them will eat the free swimming worms or even those in the tubes.”

Les said that they started with broodstock taken from local waters and now have up to 2,000 worms in their hatchery. Housed under a 90m2 tin roof, there are now 10 tanks each holding around 9m2 of specially treated water. A recirculation system with a biofilter, heater and cooler assists in providing the best conditions for spawning, larval rearing, settlement and juvenile growout. “We have excess capacity to supply other farms.”

The Safariks have been able to add F2 and F3 generations to the broodstock, selecting for larger size. Their research had allowed them to get spawns year round and they have developed a special ‘kindergarten’ which allows them to have a high density of the juvenile worms growing to two months of age when they reach around 30mm and 0.2g.

These juvenile worms are harvested by hand and then transferred to the growout tanks which have deep layers of beach sand. They calculate the numbers they put into ponds to get the most appropriate density.

Special bed preparation is undertaken before stocking with a new batch of worms to kill marine creatures still remaining in the tanks. If this is successful then they have a monoculture of marine worms so they are not feeding local marine life with their polychaetes.

Smaller worms congregate in clusters, providing self protection, however, as they grow and their tubes get larger, the worms will swim away to find new less crowded conditions. “They settle according to food levels and their highly sensitive feelers and sensory organs play a part in spatial dynamics. They are not aggressive or cannibalistic to each other. Overall movement will result in an even spread right across the tank.”

 

The worms are fed on crumbles made by Ridleys Aquafeeds in Brisbane. “The worms grow well in this formulation,” said Les, “However, we are looking forward to the time we are large enough to warrant our own feed production runs as there are a few ‘secret herbs and spices’ we know we can add to increase growth. We can also alter the HUFA and PUFA levels in our worms by changing their food.”

Les said that Abalone food was good but it was too expensive to use. “Worms love natural feeds like pieces of fish, the best so far has been pearl oyster meats left over after pearl harvests from the farm at Port Stephens.”

Feeding takes place each morning and early afternoon. The first feed is for majority of the worms, the second is for those still hungry or not yet fed. The Safariks hand feed to watch the quantities of pellets eaten as they don’t want pellets left over. In a predator free environment, the worms feel safe to crawl out to eat the crumbles. The feed is spread out to be near all tubes, so the worms doesn’t need to extend far out of their tube.

As the sea water is pumped in raw, competitors or fouling organisms such as sea anemones can be introduced into the tanks, so these are removed by hand. Any small crustaceans or fish quickly become food for the worms. The main threat to the worms could be from bird predation, but continual human activity and a swarm of energetic dogs keep them away. Nevertheless, Les and Milada have been experimenting with bird netting to exclude the birds.

 

A transportable roof on wheels is pushed around the tanks to provide cover for the workers during harvesting. The water inlet pipe is turned off and the outlet flow stoppered. A sedative is added and then the worms are hand picked out of the sediment, usually with their tube intact. The harvest is very efficient with up to 99% of all harvestable worms being removed live. The method is not stressful to the worms.

Les is experimenting with methods to make this process easier, however, in a larger operation the process would be mechanised using a fish pump and vacuum similar to that used overseas for worm and cockles.

Plastic buckets of the market size worms are quickly taken to a wash down tank where the excess sand is removed. The worms are then transferred to plastic prawn crates with about 3cm of clean sand into which they quickly burrow. A gentle flow of clean water keeps the mass of worms cool and well oxygenated. After a purge time of several hours, the worms are re-harvested and cleaned ready for live transport.

Aquabait have been shipping live worms by air as far as Perth, Melbourne and Brisbane. However the cost of freight is really hurting them; it costs us more than $50 in freight per $300 worm shipment, so they are now examining options to establish farms in other areas.

As they are a perishable product, the maximum time the worms can be transported live is around 20 hours tank to water. Frozen product is much easier to transport, and larger consignments can be built up over time to allow cost savings in transport .Frozen product is now being sent all over, and the use of these by a few aquaculture hatcheries has created some major interest. There is a sliding scale of prices, for 1-10kg it is $77/kg, 11-50kg $66/kg, 51kg and more is $55/kg (all GST inclusive).

 

Les and Milada now see aquaculture as a huge volume market, particularly with feed companies following in the foot steps of Alicorp. Fish Farming International (April ’07) reported that Alicorp, one of the South America’s largest aquaculture feed manufacturers, purchased the Holland-based worm farm Dragon Feeds.

According to Les, their current facility is purely a pilot scale one. “We know we need to produce and sell at a more competitive price, but the demand from aquaculture will be huge. We have plans and technical drawings for a series of 100tpa production plants, each with modular construction of the banks of tanks to be phased in over a 4 to 5 year period.”

“We would go for 10m wide and 100m long tanks and use fish pumps with special screens to harvest them like some cockle harvesting in Europe. The water could then be returned to the tank with sediment for the next crop to be grown.

“Worm farming is similar to other types of aquaculture – a number of different producers are required to fill big demand from aquaculture feed mills, bait fisherman and ornamental fish keepers including the public aquariums and zoos.”

Les also believes the filtering capacity of the worm tanks would also have benefits for effluent water treatment. “The worms are excellent for bioremediation. From 2002 until now we have had better water quality discharging from the farm in comparison with intake in terms of suspended solids, potassium, nitrogen and ammonia, even though we putting in more than 40kg of feed with 40 % protein level into the ponds every day. Now we are aware of this excellent break through and we definitely need to undertake further research on this.”

 

 

For more information contact:

Les Safarik, AquaBait, 
PO Box 5107 Dora Creek, 
NSW 2264.

Tel: 02 4973-5505
Fax: 02 49730-5515
Mob: 0410 794-173
email: les@aquabait.com.au 

Key Management Decisions for AquaBait include:

 

Key Performance Indicators (KPIs) include:

 

 

Chef Yann writing on his blogg Food Lorists posed the following question – “One of the characteristics of a fresh saltwater fish is its distinctive smell of seacoast air. Why is that?”

His reply: “The ocean aroma of the seacoast comes from compounds called bromophenols. These molecules are synthesised by algae and some primitive animals from bromine; an abundant sea water element. Present in sea water, bromophenols are propelled into the seacoast air by the actions of the waves and the spray, where we smell them directly.

Wild saltwater fish also store bromophenols either by eating algae or algae eaters. This is how the aroma of fish reminds us the seacoast air.

On the other hand, farmed saltwater fish can lack of this aroma because fish feed doesn't contain any bromophenols. Nowadays, some fish farmers supplement their artificial feed with these compounds, but nothing is worth the real McCoy.”

Ref: http://foodlorists.blogspot.com/2007/03/why-does-fresh-fish-remind-us-smell-of.html

 

Research published in the Journal of Aquatic Food Product Technology (Vol 1 No. 3-4, p 43-63, 1992) reported that bromophenols contributed to marine-associated flavours of fish and seafoods with “salt-like flavour attributes”. A combination of selected bromophenols added to vegetable oil gave a herring oil-like flavour to the oil.

Research by Dr Frank Whitfield and colleagues at CSIRO in the late 1990s (Whitfield et al 1998, 1999), found that marine polychaetes are major sources of bromophenols in Australian benthic fish carnivores and some omnivores, and were important in the flavour of these ocean fish.

Refs: Whitfield, F.B. et al 1998, Distribution of Bromophenols in Species of Ocean Fish from Eastern Australia. J. Agric. Food Chem., 46 (9), 3750 -3757.

Whitfield, F.B. et al 1999, Distribution of Bromophenols in Species of Marine Polychaetes and Bryozoans from Eastern Australia and the Role of Such Animals in the Flavour of Edible Ocean Fish and Prawns (Shrimp). J. Agric. Food Chem., 47 (11), 4756 -4762.

According to Matthew Siderhurst from Colorado State University, bromophenols and other brominated organics comprise a largely marine group of important chemicals that mediate ecological interactions. Early work on the organobromines secreted by marine worms, largely bromophenols and bromopyrroles, pointed to their having both anti-microbial and anti-predation properties. In addition to these findings bromophenols have been shown to serve as negative recruitment cues for juvenile sedimentary dweller (polychaetes and bivalves) indicating that they may also play an important role in determining the composition of benthic assemblages.

Ref: Matthew Siderhurst (2000), Polychaetes and Hemichordates: a Model System Toward Understanding the Ecological Relevance of Marine Organobromines. Email: Spider@lamar.colostate.edu