“Kill them to see if they will die” was the takeout from the shrimp genetics guys in the industry at that time in the late 1980s.
Yes, the French (FA) had stressed shrimp in their Tahiti R&D facility and come out with some number like 35 possible viruses and diseases for vannamei.
Simple survival of the fittest and accelerated natural selection was modus operandi, with those that survived becoming founders for breeding.
This is possible due to the rapid t/o life cycle of vannamei and sheer numbers of offspring one could play with.
So when I artificially inseminated and spawned two vannamei on a beach in Mexico in 1988 that was the SOP. The fertilized eggs were put in a plastic bin. No EDTA, no algae, no water exchange.
Busy building the first shrimp hatchery with maturation at that time, those shrimp were fed a local mix of fresh marine feed (Chuki secret formula) and at PL15 there were 15,000 survivors. A survival rate of around 5% for the two females.
Of course vannamei are not found in the US and the US Shrimp Consortium had just raised $50m from the US Senate, with a big push from Arizona to get into shrimp genetics.
So I hosted several visits from experts like Dr Lightner (Shrimp disease expert) to explain how we had developed the systems in Ecuador. The idea was to get high health offspring, robust and that could perform.
The vannamei seed coming out of maturation units initially were weak in the early 1980s. The use of wild gravid females and naup stations were what had led to the shrimp farming growth explosion in Ecuador removing much of the wild seed seasonality and environmental costs.
The industry in Ecuador thus had a breathing space to start looking at enhanced natural selection for maturation.
The 15,000 PLs from Mexico were sent to Dr Lightner at landlocked University of Arizona where he declared them specific pathogen free (SPF). All existing US commercial stocks thereafter were destroyed and these shrimp were moved to the Oceanic Institute in Hawaii, where a female called Griselda gave rise to the Kona SPF vannamei strain.
From that same hatchery in 1989 I had a batch of PLs for a farm in Texas. Dr Lightner came and took a sample of shrimp fixed with Davidsons and from same tank a live sample. The fixed sample were declared virus free. The live sample, were declared not SPF. My conclusion to Dr Lightner was that the problem must have expressed itself due to poor husbandry by his team. After all artificial seawater, who knows what feed, stress on aeroplane transmitted to shrimp…..but no! import to US denied.
Statements were issued with the US declaring that the all wild vannamei globally were infected and that they had the only stock of SPF vannamei on the planet.
Great commercial spin trying to corner the market from a scientific viewpoint.
To me shows that SPF is only as good as the husbandry used. This is also why once out of a controlled SPF facility the status was downgraded to high health for commercial purposes – just in case.
At WAS and other conferences thereafter shrimp and genetics was the sexy thing to discuss at the time. More than likely because it was high tech and transferable.
The laying down of US rules and the associated technology push was important as industry commercial control had been shown successful in other protein industries, in fact other industries.
At the time I likened the marketing to the Windows operating system which ran off a disk operating system (DOS). The background operating system for shrimp was the survival of the fittest setup that was used to get those 15,000 PLs. The SPF program the Windows marketing to the shrimp public.
The SPF founders were from artificially inseminated (AI) females and not from wild gravids. They were grown on a special diet. So already quite a bit of stress. The females were non ablated.
Interestingly first SPF from US that went to Ecuador (now why would you that with such a large natural pool available?) was a failure.
Ecuador, since then, has sucessfully continued it’s growth without SPF.
Continued use of a wild biodiverse genetic pool to enhance or test shrimp populations makes sense.