Different strokes
In reality, NNV and the iridovirus were already a problem more than a decade ago when fish farmers in Taiwan began to raise groupers. Back then breeders practiced "carpet breeding"-using huge numbers of eggs to provide sufficient numbers of surviving fry. But with growing numbers of groupers dying from viruses, what new measures can breeders take to adapt? It's a cause for concern.
Pan Jianzhang, who raises 6-cm grouper fingerlings in Jiadong, says that all fry can be carriers. The key point is whether they will actually come down with the virus. So how do you go about selecting strong-bodied fry with high levels of resistance? That depends upon the individual experience of those raising the fish. "Every-one views things a little differently." He typically looks at pond controls, water color, and the presence or absence of bubbles to determine whether the situation is good or bad.
Freshness of feed is essential, and when fry have to change tanks or ponds for cleaning, great care must be taken to ensure they are not long out of water. Because the seawater in fishponds is running 24 hours a day, so much is being used that it's hard to completely disinfect it. Except for those raising high-value giant groupers, most farmers cannot afford to invest in water circulation systems. Green groupers are of relatively low value. Pan can't justify the expense of a circulation system, and it's possible that sanitizing the water wouldn't even resolve the problem.
Pan says that most farmers raising 3-cm grouper fingerlings in Pingtung don't disinfect their seawater. Facing lower and lower survival rates, the farmers are at their wits' end.
ISO grouper standards
With the menace posed by viruses, the Fisheries Agency of the Council of Agriculture has hired researchers from National Taiwan University, National Taiwan Ocean University, and the Animal Health Research Institute to carry out research on vaccines, and has teamed up with the COA's Bureau of Animal and Plant Health Inspection and Quarantine (BAPHIQ) to establish a quality control system for aquacultural products. It aims to implement first-rate production and disease prevention standards at one stroke.
BAPHIQ's director-general Hsu Tien-lai explains that the Ma administration's push for high-value specialty agricultural products has largely been aimed at export, so that producers must adapt to the demands of the international market. And international markets in recent years have been requiring that exporters show concern for human health issues and environmental responsibility in addition to animal disease control. Various nations have developed different quality control systems. Agricultural exports to the United States, for instance, must meet Hazard Analysis Critical Control Point standards, and those to Europe must meet the EU's Good Agricultural Practices standards. There is another set of standards to meet for export to Japan. These various regulations cover the whole process of agricultural production, from plant and animal diseases, to environmental impacts, to food safety.
Because different nations make different demands, the BAPHIQ, in order to help producers planning to export to meet the market conditions of the importing countries, has created new export inspection guidelines, and revised the Fisheries Agency's quality standards at the production end, creating a unique quality-control system for Taiwan that is similar to ISO standards. These standards will be implemented throughout the production process via permits and inspections.
Safety through separation
With regard to grouper exports, overseeing agencies have developed a quality control system for breeding stock and their offspring, which is known as the "high bio-security isolation production system." It starts with inspection of fry, so as to ensure that none of them have any viruses. And it also includes standards for water supply, feed, and sanitation of equipment. The Fisheries Research Institute has already established a model breeding farm and hatchery in Tainan in the hope of getting the aquaculture industry to copy its methods of isolated production, which offers a high level of safety. So far, a few fish farmers in Tainan have adopted the model. Since the Tainan coast doesn't suffer from the same pollution problems found along the Pingtung coast and enjoys relatively clean water, survival rates under the new regimen have climbed as high as 80%.
Hsu Tien-lai believes that if fish farmers adopt this set of quality controls and vaccinate young fish before they are placed in ponds, then, based on the 70-80% survival rates for vaccinated fish in NTU labs, it should be possible to attain survival rates of 30-40% for vaccinated fish raised outside, despite the numerous complications.
Huang Youyi, who leads the Fisheries Agency's aquaculture group, explains that these quality controls are expected to be authorized in the middle of 2011. They will then be promoted in the hope of their being widely adopted.
Fish farmers and academics have called for the government to take drastic measures to resolve the problem of polluted seawater being drawn into fish ponds by overhauling the system of intake and effluent pipes along the coast. Although the government is currently building a seawater supply station to provide fish farmers with water in Pingtung's area of highest production, most farmers believe that the supply will be insufficient to meet their needs. "It used to be that a few hours was all that was needed to completely change the water in the ponds. If farmers end up needing to wait their turn for a day or two, that additional time will make it easier for the fish to suffer health problems, and in the end we're going to end up using our own pipes to intake water."
The general plan to solve the damage wrought by grouper viruses is ready to be put into place, and various government agencies are introducing measures of their own. But will these be enough to meet the needs of fish farmers on the front lines and resolve various implementation problems? The answer remains to be seen.
Disease control measures in grouper aquaculture
Stage |
Disease prevention strategies |
Important supplementary measures |
Gathering breeders |
Quarantine |
P、D、G、M、L |
Maturing of breeders |
Avoidance |
P、D、G、M、L |
Hatching |
Avoidance and prophylaxis |
P、D、G、M、L |
Fry |
Prophylaxis and treatment |
P、D、G、M、L、A |
Immature and adult fish |
Vaccination and treatment |
P、D、G、M、L、A、V |
Important supplementary measures:Veterinary management and process control in production (P); diagnosis and treatment (D); good aquacultural practices (G); disease monitoring (M); laboratory support (L); management of aquacultural facilities and water supply in production zones (A); vaccine development and use (V).
source: BAPHIQ