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Partners work to RAISE GLASS EELS BY JOHN MOSIG M ark Fantin's started raising barramundi in 1990 at his company, Sugarland Barramundi, situated just off the Bruce Highway, 30 minutes south of Cairns. That all began to change in 2005 when He took some juvenile eels from John Neilsen's Eels Down Under at Kuranda to see how they would go in his ponds. The eels reached 3-4 kilos in 24 months and Mark has been phasing out barramundi and stocking with eels as seed stock has become available. Since then John and Mark have formed a working partnership that has benefi tted both operations. John has the glass eel harvesting licences and the nursery to wean and raise the glass eels to elvers. Mark has the growout facilities to take them to the next stage. The farm at Sugarland consists of 10 growout ponds of varying sizes totalling 3ha. The ponds are bottom-draining and are all connected and screened so water can be moved around the farm at will, depending on the water quality and stock requirements at any given time. When it comes to aeration, he uses a combination of a 2.5hp paddlewheel and 1.5hp aerojet aerators. Water comes from an uncapped bore at a pH of 6.5 to 6.7. Carbonate hardness is 50ppm and the temperature is a constant 23.5˚ Celsius. Mark jokes that he should have set up a water bottling plant a long time ago. With bottled water now coming under carbon emission scrutiny, he feels he may have missed the boat on that one. The ponds are not netted and the only major predators are Asian black-necked storks, known as jabirus (Ephippiorhychus asiaticus). "I've lost count of the number of jabirus we've raised on the farm," Mark says. "It must be over 20, but the tourists like to see them around the place and they're never here in numbers, so they pay their way." Water temperatures down on the coast plains range from 20˚C to 30˚C most of the time. Mark says they can get down below 20˚C for four to eight weeks in a cold winter and a bit above 30˚C in an unusually cloudless summer, but for nine months of the year they are above 25˚C. The optimum temperature for long-fi nned eels is between 25˚C and 28˚C. Metabolism is slower during the short northern winter and they reduce feeding rates. "We probably lose 20 percent of our normal growth during this time, but they have a feeding and growth spurt as the temperatures drop in June. We found the barramundi did the same thing." The 0.5ha settlement pond is a wetland feature of the farm. Covered in lilies, it adds to the ambience and strips nutrients from the pond water. They recycle around 20 percent of the water that passes through it. The remainder is used in irrigation, including a 2ha native wood lot, which also adds to the charm of the tourist fi sh-out ponds. Mark has tended to steer away from the tourist side of things since moving into eels. "We have some barramundi in the pond with a fair bit of size on them, but after four or fi ve years of fi shing they have become a bit lure shy. At the end of the day it all becomes a bit demanding and eats into your family leisure time. It's not what life's about." Eels come in two sizes, depending on whether they are males or females. The males tend to remain small and 800g would be the average size of a crop from the male ponds. On the other hand, the females can reach eight to 10 kilos in four to fi ve years, but most of them are sold when they weigh three or four kilos, which takes 12 months to two years. Ready for market. Mark Fantin proudly displays the results of his efforts Larger eels attract a premium. They will be paid more per kilo for a female weighing three kilos than an 800g male. And they will receive more per kilo for an eel weighing eight kilos than one weighing three kilos. John and Mark have yet to decided exactly what size represents the best return for them. "The more females we can generate makes a massive difference in the overall tonnage we can produce, " says Mark. "There's a premium for the extra large stock, but we don't at this stage have the capacity to run that long on a lot of stock. Time is money everywhere these days, and a fi sh farm is no different." The eels come onto the farm from Eels Down Under as 300g juveniles and sexual dimorphism will have taken place by the time they reach 500g. After three months they will weigh an average of 600g and are graded into male and female ponds. Any male eels over 600g are sold. They have little growth 6 ■ NZ AQUACULTURE ■ JANUARY/FEBRUARY 2012