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SPF Broodstock

 

Shrimp News: I had to do a lot of guessing while summarizing this discussion.  If I made a mistake with something you wrote, send me an email, explain the mistake, and I’ll correct the record within a day or two.  I like to keep the record straight!

 

Vancl (vanadis@163.com): Why haven’t specific pathogen free (SPF) broodstock and postlarvae from Hawaii been successful in Latin America, especially when they find such a good market in Asia?

 

Daniel Gruenberg (daniel@acquestra.com): Vancl, Asia utilizes smaller, intensive ponds that make biosecurity more practical, so SPF animals had a big advantage over the wild and pond-raised broodstock in Asia, which was frequently contaminated.  Latin American farms use large, flow-through ponds and no biosecurity, so the industry focused on disease resistance, rather than SPF animals.  The SPF Hawaiian animals didn’t need resistance to survive in the small well-controlled ponds of Asia, but in Latin America merely being SPF wasn’t enough.

 

That being said, shrimp genetics has changed a lot since early mortality syndrome (EMS) hit Asia.  In Thailand, for example, Hawaiian broodstock are losing market share to locally produced, specific-pathogen-resistant (SPR) broodstock.

 

Enterocytozoon hepatopenaei (EHP) is a major challenge now.  For some good background information on EHP, click here.

 

SPR and SPF are not mutually exclusive.  Having clean larva is plain common sense, but the concept of how you select and how you get to SPF status is different for different broodstock companies.

 

I think we have seen a lot of progress in shrimp genetics since EMS came along, and that trend is likely to continue into the future.

 

Broodstock companies are competing hard and producing more resistant and faster-growing animals, giving farmers more and more options.

 

Enrique Mi Nino (enriquemlnino@gmail.com): Enterocytozoon hepatopenaei (EHP) is also known as “cotton disease”.

 

Daniel Gruenberg (daniel@acquestra.com): : Enrique, although EHP and cotton disease are caused by similar organisms, they aren't the same disease at all. Their gross signs differ, and so do their controls.

 

Ramesh Sivaram (sivaramr@hotmail.com): Here’s some background information on EHP:

 

• EHP is a microsporidian parasite that causes slow growth in shrimp.

 

• In 2001, EHP was first reported in Australia as an unknown and unnamed

microsporidian in the hepatopancreas of Penaeus japonicas.

 

• In 2009, in Thailand, it was characterized and named from black tigers
shrimp P. monodon.

 

• It’s an oval-shaped, spore-forming parasite, measuring 1.7 x 1.0 μm.

 

• No specific signs of infection are seen in shrimps infected with EHP.

 

• It’s confirmed either by microscopic or molecular methods.

 

• EHP is transmitted through the things shrimp eat and eventually infects
all the internal organs.

 

• Reports reveal that EHP is endemic Asia and Australia.

 

Francisco Velasquez (kikoescorpio2@yahoo.com): Getting back to Vancl’s original question, I think the main problem was that companies that imported SPF animals into Latin America were not prepared to receive and manage them.  I know of one company that invested a lot of money in SPF broodstock and developed a biosecurity plan to receive and manage them, but didn’t upgrade its water treatment system.  The animals were healthy, but they picked up some local bugs and passed them on to their larvae, which died one week after stocking.

 

Enrique Mi Nino (enriquemlnino@gmail.com): SPF broodstock and postlarvae from Hawaii are expensive.  Airfreight costs are high.  Postlarvae cost $20 per thousand.  The ecosystem and pond sediments are full of diseases in Latin America.  The PLs may be clean when stocked, but they die soon after exposure to the diseases in the ponds.

 

Giovanni Chasin (gchasin_valencia@yahoo.com.br): Vancl, here’s an example to help answer your question.  In Brazil, non-SPF postlarvae with a low prevalence of whitespot virus and a high prevalence of IHHN virus (in the absence of Vibrio parahaemolyticus) gave us good survivals in open earthen ponds.  We would like to have IHHNV SPF animals, but they are not available.  Other farmers in Brazil prefer to grow WSSV/IHHNV-SPF animals in their more controlled super-intensive systems.  On the other hand, in Venezuela, the use of SPF/SPR TSV-C lines is mandatory.  The point is that different pathogens, virulences, pathogenicity, environments and management and production systems affect the choice of broodstock and seedstock.

 

Enrique Mi Nino (enriquemlnino@gmail.com): Giovanni is taking about Brazil.  In Central America, our hatcheries supply good-quality, resistant/tolerant PLs.  We have no problems with IHHNV.  WSSV hits us only during periods of heavy rain and cold weather.  Brazil appears to have all the diseases all of the time.  In Central America, we are doing just fine with our homemade seedstock.

 

Hervé Lucien-Brun (hervelb@gmail.com): SPF does not mean disease resistant; it just means your shrimp don’t have some of the generally known pathogens.  That’s all.  It is an illusion to believe that you can keep and outdoor pond or tank free from pathogens.  You can only stop some of the pathogens.  This is true all over the world.  The Ecuadorian’s can produce good crops in the presence of WSSV and EMS because they have developed resistant strains of P. vannamei.  Whenever SPF stocks were introduced in Ecuador, they failed.

 

Why the don’t Asian shrimp farmers develop resistant stocks?  I don’t know.  You will have to ask them.

 

In my opinion, the Ecuadorian system has a weak point: most of the broodstock are grown on local farms and then screened at broodstock facilities before they are used to produce the next generation of broodstock.  This is risky because you can only screen for known pathogens.  What about new pathogens?  The best system would be to develop an indoor, biofloc breeding center to keep the pathogens (know and unknown) away.

 

Jorge Cordova (seabizec@yahoo.com): Giovanni, I found your statement very interesting: In Brazil, non-SPF postlarvae with a low prevalence of whitespot virus and a high prevalence of IHHN virus (in the absence of Vibrio parahaemolyticus) gave us good survivals in open earthen ponds.  Back then, in the presence of WSSV, ponds stocked with PLs that had IHHNV would perform a lot better than those with no IHHNV.  At that time, the general idea was that IHHNV protected the shrimp from WSSV.  So, my question is: How did you measure prevalence?  Did you check the postlarvae?  The broodstock?  And then compare the data to the performance in your ponds.

 

I‘ve been communication with a very knowledgeable friend in Asia who says that when EHP is present in shrimp, they seem to be protected from EMS.  I would like you to elaborate on this topic because there might be something to learn from it.

 

Jim Wyban (jim.wyban@gmail.com): Success in shrimp farming is a complex proposition.  To say SPF did not succeed in Latin America ignores a very important success story.  When Robins McIntosh was production manager at Belize Aquaculture (BAL), he used SPF broodstock from my company (High Health Aquaculture) for their first two years of production.  Their results were fantastic: 17 metric tons per hectare from zero-exchange, open ponds.  Robins published a series of papers in the Global Aquaculture Advocate magazine, documenting his results, which solidified his professional reputation and led to his recruitment by CP Foods in Thailand.  After two years of huge successes using imported SPF broodstock, BAL elected to switch to homegrown broodstock, and their results were never the same again.  Success with SPF is not about geography; it’s about systems.

 

Breeding for disease resistance was a core component of our earliest SPF breeding programs.  We did it first with the Taura virus and with other viruses later.  It’s crazy to think that SPF and SPR are mutually exclusive or competing strategies.  Despite the many SPF deniers on this list, SPF Vannamei continue to dominate Asia production, which, of course, dominates world production.  I estimate at least 15 million metric tons of shrimp worth $150 billion have been produced from SPF broodstock.

 

Daniel Gruenberg (daniel@acquestra.com): Jim, with all due respect, people with different opinions than yours should not be labeled deniers as if SPF is a religion complete with blasphemy and heretics.

 

Nobody here is denying the utility and benefit of stocking clean animals—and you were certainly the pioneer in this area.  Since that initial innovation, problems have popped up, and SPF alone or even TSV-resistant stocks, for that matter, could not save Asian production.

 

It’s hard for me to read with a straight face your comments about the “success” of Asian shrimp farms when production at most farms is down 50-70%, after four plus years of EMS and EHP.

 

There’s a big gray zone between SPF and SPR.  You’re right, they are not mutually exclusive, but the challenge and selection methods have key differences that produce different results.

 

Hawaiian animals failed miserably in Thailand after EMS.  Since EMS, only firms that are doing local breeding and selection are having success these days.  And I must say we see a big difference in pond performance in the newer locally selected strains versus the clean but naive Hawaiian animals.

 

Jim, nobody denies you your legacy, but when I see 80-90% of the ponds still empty, with EMS, EHP and WSSV and whatever else creating big problems for the industry, you should not use the “D” word.

 

How can Hawaiian broodstock companies compete if they don’t expose their animals to the same environment that they will be grown in?  There is a strong theoretical argument for local selection and the results, so far at least in Thailand, seem to support the theory that local selection is not and option, but a necessity.

 

Using the outlier BAL as proof of SPF’s viability in Latin America ignores the fact that BAL’s model was completely different than nearly every other farm in Latin America.

 

Yes, no denying that Robins did a great job there, but to claim that all his successes were due to SPF and his failures due to lack of SPF is a bit of a stretch, to say the least, and even counter to your argument that success is a “complex proposition”.

 

Again nobody denies your innovations and their positive impact on the shrimp industry, but it isn’t 1995 anymore, and the industry needs even more innovation and competition to move ahead and deal with the new challenges we face.

 

Vijayan K.K. (vijayankk@gmail.com): Broodstock companies are competing hard and producing more resistant and faster-growing animals that provide more and more options for farmers.  When we select for growth, the outcome is mostly positive, but when we add another trait, like disease resistance, growth is compromised.

 

A lot of genetic work needs to be done.  Different pathogens, virulences, environments, species, and production and management systems, will lead us in the right direction.  We recently had a 4.5-ton harvest of 18-22-gram Indian white shrimp (P. indicus) in 110 days from a pond in the state of Orissa, stocked with WSSV-free PLs.  Success with SPF is not about geography; it’s about systems.

 

Marcel Selfer (marcel.selfer@gmail.com): SPF is not the solution to the disease problem in shrimp farming, but it is part of the solution.  Without it, the risk is too high.  However, it does not guarantee the success of a crop.  Many other factors play a role.

 

At our hatchery in Sri Lanka, we produce SPF PLs.  There’s a high density of farms around us, and whitespot is a major problem.  Farmers that stock non-SPF PLs have over a 75% chance of getting whitespot, forcing them to early-harvest 10-to-15-gram animals.  Farmers that buy PLs from us also get whitespot, but it occurs 2 to 4 weeks later than with non-SPF PLs, allowing those farmers to harvest 15-to-20 gram animals.

 

At our farm we disinfect the pond, stock SPF PLs, don’t get whitespot and harvest at 25-to-35-gram animals.  SPF PLs give us a good start.  Depending on what other biosecurity and management measures are taken after stocking, diseases can be delayed, or even avoided.

 

Jim Wyban (jim.wyban@gmail.com): I have 27 years in shrimp farming, mostly with hatcheries and broodstock, and have experience working in the Western and Eastern Hemispheres with the following diseases: IHHNV, BP, TSV, NHP, EHP, WSSV, EMS and YHV.  New diseases, old diseases, they don’t go away.  We need more genetic work to win the battle against shrimp diseases.

 

Alain Michel (alainhenri@aol.com): Jim, I fully agree on the success of SPF P. vannamei, but I question if it is due to the SPF concept or the species.

 

Let’s look at the history of shrimp farming.  It started in Southeast Asia with many different species, and then the giant tiger shrimp (P. monodon) quickly became the dominant species, reigning for a couple of decades.  Now, P. vannamei is the dominant species because it’s easier to reproduce, less expensive to feed and works well at high densities.

 

You were able to develop SPF-SPR vannamei postlarvae, and at the beginning, the results were good in Southeast Asia because monodon’s viruses were less aggressive with vannamei.  But now they have become aggressive with vannamei.

 

In South America in the 1970s, vannamei was successful, but then new pathogens caused farms to fail.  SPF postlarvae were introduced in an environment where the pathogens were well established.  The example of Belize and the success of Robin McIntosh with SPF vannamei could be due more to the use of biofloc techniques with zero-water exchange than to the SPF status of the postlarvae.  It is now well known that biofloc technology reduces the threat from viruses, but the day will come when they mutate and adapt to the biofloc environment.

 

Definitely, vannamei is an easier species to culture than monodon, but big monodon garner higher prices.  That’s why there is a tendency to bring back monodon with postlarvae selectively bred for disease resistance and other traits.

 

So, vannamei has many advantages, and it is better to start with SPF postlarvae than with a pathogen carrier, but it’s possible to do the same thing with local strains of monodon.

 

Jim, you succeeded because you developed SPF/SPR vannamei—and because vannamei is inherently a great species for shrimp farming, a real natural!

 

Giovanni Chasin (gchasin_valencia@yahoo.com.br): Jorge, it’s nice hearing from you.  Yes, we stock postlarvae with a low prevalence of WSSV.  From 1.5 to 14% of the PLs we stock are whitespot positive.  For every three million PLs we stock, we send five sample batches of PLs to a PCR lab.  The same for IHHNV.  The lab sends us the prevalence for every sample.  We do not check for WSSV in the growout ponds.

 

In Brazil, animals with a high-health status that are WSSV and IHHNV free do not do well in earthen ponds; however, in super intensive systems with and without greenhouses and no biosecurity, they do very well, reaching production levels ranging 20-45 metric tons of 18-gram shrimp in 100-120 days.  The animals that die are always the biggest ones, usually when they molt.

 

Jim, I agree with you.  Even though I did not work with your animals in Venezuela when TSV-c hit the farms there, it would have been very hard or impossible to re-start production without your SPF/SPR lines.  They were an immediate success.  I’ve been in the shrimp farming business for 30 plus years and never see anything like that.  TSV-c is a nightmare, and to be able to re-start production in a very short time was amazing.

 

Nelson Gerundo (nelsongerundo@yahoo.com): In the Philippines, in the past, vannamei postlarvae produced from homegrown, pond-reared, exposed broodstock from non-registered hatcheries and sold to small-scale shrimp farmers without health clearance certificates were thought to be one of the reasons for the spread of introduced notifiable shrimp diseases.  Perhaps, to a minor extent, that’s still true today, particularly on the island of Luzon.

 

Sources: 1. The Shrimp List (a mailing list for shrimp farmers).  Subject: About SPF Broodstock.  February 9 to 12, 2017. 2. Bob Rosenberry, Shrimp News International, February 14, 2017.

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