Back in 2018, eggs from infected shrimp spawners would be promptly chlorinated and disposed – all 200,000 to 1 million of them per brood – to quell notorious pathogens that continue to devastate shrimp farms worldwide to the tune of billions of dollars yearly.
This was the practice at the SEAFDEC/AQD Tiger Shrimp Spawner/Broodstock Facility in Iloilo, Philippines where incoming spawners are screened for pathogens, through polymerase chain reaction (PCR) tests, before allowing their eggs into a highly biosecure hatchery.
Upon releasing their eggs, the spawners, are tested for the white spot syndrome virus (WSSV), monodon baculovirus (MBV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), yellow head virus (YHV), acute hepatopancreatic necrosis disease (AHPND), and the parasite Enterocytozoon hepatopenaei (EHP).
To end the wasteful abortion of shrimp eggs and boost the production of shrimp seeds, SEAFDEC/AQD scientist Dr. Leobert de la Peña started disinfecting them and soon found that disease-free postlarvae can be successfully produced from infected spawners.
“Now we collect the eggs from each spawner and wash them with UV (ultraviolet) light-sterilized seawater, after which the washed eggs are then disinfected with iodine before being finally rinsed with sterilized seawater,” said Dr. de la Peña.
The Food and Agriculture Organization of the United Nations recommends that shrimp eggs and nauplii (newly-hatched shrimp) must be washed and disinfected appropriately to prevent the transmission of viral, bacterial, fungal, and other diseases from broodstock.
To date, disinfected eggs from several batches of infected spawners continue to be free from diseases, helping the experimental hatchery achieve a 19 percent survival rate (newly hatched shrimp to postlarvae) in 2020, more than double compared to only 9 percent in 2018 before egg disinfection was done.
Disinfection of eggs helped the experimental hatchery cut losses from the disposal of infected spawners and their eggs. In the Philippines, each spawner costs P1,500 to P2,000 (US$31 to US$42), while eggs that successfully develop to postlarvae are P200 to P250 (US$4 to US$5) per thousand when sold.
The measure is made even more important in the face of an increasing number of wild-caught spawners purchased by the facility that are found to be infected with the notorious WSSV.
“In the mid-2000s, we found that between 0.3 to ten percent of shrimp in the wild are infected with WSSV. Recently, we found out that about 60 percent of the spent spawners that we have tested are infected,” Dr. de la Peña shared.
While spawning stress may help make pathogens more detectable in PCR, the tenfold increase gives a rough estimation of the alarming spread of WSSV that leads to significant economic losses for hatcheries.
Oplan Balik Sugpo
The SEAFDEC/AQD tiger shrimp spawner and hatchery facilities are at the centerpiece of SEAFDEC/AQD’s Oplan Balik Sugpo program launched in 2017 by Chief Dan Baliao, to boost the production of high-quality shrimp seeds and help revive the tiger shrimp industry in the Philippines.
The Philippines was once one of the top shrimp-producing countries in the world, harvesting 120,000 metric tons of tiger shrimp in 1992, worth US$ 300 million that year (US$ 571 million or Php 27.4 billion in 2020, accounting for inflation). Due to various shrimp diseases, the current national production is only roughly a third of the volume in 1992 at 42.45 thousand metric tons, worth Php 20.60 billion.
“Technologies in shrimp farming are constantly evolving, and we, as scientists, need to adapt depending on the current situation on the field,” said Dr. de la Peña.
Chief Baliao shared that SEAFDEC/AQD is further refining its protocols and technology for future collaborations with Philippine government agencies such as the Bureau of Fisheries and Aquatic Resources (DA-BFAR) and the National Fisheries Research Development Institute (NFRDI).
“SEAFDEC/AQD is only getting started,” he added. “There is still much to be done, but our scientists and technicians are hard at work at refining our protocols and technology for the benefit of our stakeholders.” /JR PAGADOR, RD DIANALA