Sino Agro: We can fix problems farming freshwater shrimp at megafarm
By Louis Harkell Nov. 17, 2017 09:24 GMT
ZHONGSHAN, China -- Solomon Lee, Sino Agro Food CEO, said problems farming freshwater shrimp at the "megafarm" in Guangdong, China, are fixable, despite the delays to date.
More than two years after Sino Agro announced shrimp production would soon begin at the megafarm, its first operational section of Sino Agro's megafarm hasn't harvested any shrimp and tanks are largely being used for lower-value species such as jade perch.
The delay raises questions about the attainability of the projected production figures announced by Sino Agro. However, Lee has said that the delays are due to funding shortfalls and technical issues that can be solved.
The technical issues relate to farming Macrobrachium rosenbergii at high densities, according to Sino Agro's chief scientific officer Anthony Ostrowski, who joined the megafarm in 2015.
When farmed at high densities, macrobrachium do not grow uniformly; males which grow fastest are territorial and cannibalistic; and once a large shrimp has established dominance smaller male shrimp stop growing, he said.
During its visit, Undercurrent News saw first-hand problems with shrimp cannibalism, and slow and heterogeneous growth.
Fixing the problem
Ostrowski proposed several solutions to fixing the problems farming macrobrachium at the farm. These range from immediate solutions, such as from grading shrimp by hand, to long-term solutions, like developing a domestication program, he said.
The immediate option involves workers at the megafarm "culling out" the larger macrobrachium during the grow-out phase, he said. Essentially, this method involves removing larger macrobrachium from the tanks individually by hand, he said.
According to Ostrowski, by taking the larger, aggressive shrimp out of the tanks, the other males can grow normally -- or at least until other males undergo a growth spurt and problems reoccur. Ostrowski said calling out the larger macrobrachium is how Sino Agro successfully harvested macrobrachium at Prawn Farm 1 in Enping, another farm built and managed by Sino Agro.
At the megafarm, culling out shrimp could take place monthly, said Ostrowski, when the shrimp are transferred from smaller tanks to larger ones, as per the megafarm's partial harvest, phased grow-out system. During Undercurrent's visit to the megafarm the larger shrimp were easily identifiable due to their striking blue claws.
However, Ostrowski conceded this "culling out" method would be labor intensive; Prawn Farm 1 has harvested about 700 metric tons of shrimp using this method, he said, whereas the megafarm envisages production in the tens if not hundreds of thousands of tons.
While Ostrowski did not mention mechanical grading, Mathieu Wille of the University of Ghent, Belgium, told Undercurrent this alternative would require "serious engineering". "We thought it could be possible to have something like vertical grids in different sizes which move horizontally through the tanks," he said, but, "we haven’t really pursued the idea".
Second, the megafarm could use newly-developed shrimp neo-males or super-females to produce all-male or all-female shrimp larvae stock, said Ostrowski. All females would grow more uniformly and would be much more docile than males, said Ostrowski, adding that populations of all males or all females would require less culling and less handling than mixed populations.
Several industry experts also referred Undercurrent to this option. Enzootic, a California, US-based agro-biotech company, commercially supplies super-female broodstock prawns guaranteed to spawn 100% female progeny. A field study conducted in 2011 showed all-female populations give higher production and product value, compared with males farmed under intensive conditions.
Third, the megafarm could start a domestication program, said Ostrowski. This would look to breed macrobrachium with more desirable traits. It would begin with a specific pathogen free program, which could take a couple of years, then look at traits for several years afterwards. There is also a very lucrative market in China for macrobrachium postlarvae, he added.
Ostrowski conceded this solution could take up to five years before it started making inroads, however. Even then it might not be successful; in the 1990s researchers tried to breed macrobrachium rosenbergii with smaller head -- heads comprise around 40% of a macrobrachium shrimp -- with limited success.
Fourth, Ostrowski wants to develop a modified shrimp biofloc for the indoor RAS—biofloc is a soup-like mixture of bacteria, algae and other nutrients that can be used to create more hospitable environments for shrimp and reduce solids waste in outdoor ponds -- to help improve growth and survival rates. To this end the project has hired a Chinese-born, US-educated microbiologist who works directly under Ostrowski. "Maintaining an appropriate balance of microbes indoors is just as important as in outdoor systems," he said.
Fifth, Ostrowski wants to build a water treatment plant and boiler, he said, as the megafarm currently has neither, although they are part of the original plans. Water in the tanks is presently sourced from rivers or canals, he said, which has high organic content and disease vectors that must be removed prior to entry to the buildings. He said without a boiler system to heat water the farm cannot farm shrimp year-round.
These solutions will likely require further investment, which the company is seeking and it remains unclear when the possible solutions may be implemented.
But Lee said in a email to Undercurrent that the company is working on finding solutions.
"Delays in farming macrobrachium in the indoor tanks are due to delays in funding to complete the farm and modifications required in infrastructure we have already identified at this site. We are, in fact, researching ways to increase density in our indoor tanks at the site now," he said.
Lee added the megafarm is also researching indoor culture of vannamei. "We are currently researching the culture of Litopenaeus vannamei in our indoor RAS and have already grown them commercially in our outdoor RAS systems at AF3 [Aquafarm 3] (and recently in non-RAS ponds at AF4 [megafarm] as noted above)."
"We do know shrimp (Litopenaeus vannamei) have been raised in zero-exchange, or minimal water exchange, and even clear water indoor systems in the US already, so there is some level for optimism for our indoor RAS. We also have the saltwater in place at the megafarm to raise them at whatever salinity we deem best. The final decision will come down to economics of production."
Credit
louis.harkell@undercurrentnews.com
https://www.undercurrentnews.com/2017/11/17/sino-agro-we-can-fix-problems-farming-freshwater-shrimp-at-megafarm/
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