As no endemic penaeid shrimp were present, various species were imported into Tahiti at Centre Océanologique du Pacifique (COP) since the 70s for a shrimp aquaculture development program lead by Alain Michel and his Aquacop team: P. occidentalis, P. japonicus, P. aztecus, P. merguiensis, M. ensis, P. monodon and ultimately L. vannamei and L. stylirostris. Out of all candidates, L. stylirostris has been the only species kept especially for its ability to better resist to colder subtropical water temperatures in both Tahiti and New Caledonia.
Several batches of L. stylirostris post-larvae were then received in the 80s from various locations in Mexico and Panama to increase genetic diversity of a founder stock. During experiments run at COP, some batches experienced mass mortality events. Survivors were systematically kept and crossed to develop Tahiti’s own domesticated stock in order to stop any more import, since first infectious diseases had already been reported to badly hit some shrimp industries. Studying the health status of COP domesticated population, typical IHHNV lesions were found present in specific tissues. However, they showed no signs of infection like what was reported in those countries. Once characterized as a parvovirus and when experimental infections were developed in University of Arizona laboratory, collaborating assays of infectious challenges were run on juveniles of this Tahitian population and from other origins. Results concluded that this population was resistant to IHHNV, while carrying the virus at low levels, while other populations were highly sensitive. That was when the hypothesis of low virus load could be protective against serious infection. This strain was then named as SPR43.
In 2005 a genetic program was initiated in New Caledonia to correct possible negative effects of inbreeding. A SPF/High Health L. stylirostris population was imported from Hawaii and field assays were performed with pure SPF and crossed SPFxSPR stocks, to compare their results with the original stock. Both “newly developed” stocks experienced signs of typical IHHNV infection, showing that the tolerance of SPR43 strain to IHHNV had a genetic basis, and was potentially reversible if important polygenes were lost during the “new blood” introduction. Facing a progressive increase of IHHNV infections in those “new” stocks, local partners decided in 2008 to destruct them and keep only the successive generations of “pure” SPR43, which remains nowadays the first L. stylirostris still successfully reared thanks to a pathogen resistance.
These results are consistent with more recent disease resistance programs in several countries, especially L. vannamei successful Local Pathogen Resistant (LPR) programs run in Ecuador.