If you dig through Operation Predator, you should come up with two quite different stories, and the little information I can glean is that the two initiatives are not directly linked.
In the US, Operation Predator was started in July 2003 by the U.S. Immigration and Customs Enforcement to protect children from sexual predators.
https://en.wikipedia.org/wiki/Operation_Predator The Wikipedia article does not make it clear that a sexual predator is considered to be someone having certain categories of sex with a person under 18 years of age, whether that person is considered to be at or above the age of consent in the country where the ‘offence’ took place.
The major thrust of Operation Predator appears to be to detect foreign national sex offenders, with the aim of deporting them from the US.
Another strand was the PROTECT Act of 2003, designed to halt US citizens from indulging in child sex tourism to Thailand, Cambodia, Mexico and Costa Rica. US citizens were deemed to make up 25% of such sex offenders, the largest contributors.
Operation Predator in conjunction with other US organisations built up a large database of child pornography images, and appears to have an advanced capability for searching through these. Operation Predator was communicating with Interpol and appears to be linked through global systems to CEOP. Whether Madeleine McCann was ever run through the Predator database is unclear.
Operation Angel Watch is another U.S. Immigration and Customs Enforcement initiative. This tracks people is the sex offender registry who are considered likely to indulge in child sex tourism, and notifies destination countries when those people travel abroad. In 2007, Angel Watch sent 1,700 leads to 100 countries.
The disappearance of Madeleine McCann does not appear to fit child sex tourism for all sorts of reasons, but it would be interesting to see how many alerts were sent to Portugal around April/May 2007.
Turning to Portugal, Operation Predator was an effort that resulted in raids in early October 2007. The news appears in media reports dating from around 11 Oct 2007, but I have not found a definitive date for the raids. The operation was reported to be 6 months in the planning.
All of the media reports naming the leader of this effort say it was Paulo Rebelo. However a couple of forum reports say that Rebelo was unconnected to this, with one saying he was working on robberies. Since 2 Aug 2007 was the date at which Amaral was removed from the Madeleine McCann investigation, it seems odd that Rebelo would leave Operation Predator just as the raids were about to come to pass.
Anyway, the Portuguese Operation Predator resulted in 80 arrests with 150 devices seized (PCs and mobile phones etc.) with 75 properties searched. The main effort was in Lisbon with the Azores and Madeira being prominent. This makes it look like it might have been based on the SIS year 2000 report which named these areas, plus Porto, as the main problem zones. There is no specific mention of the Algarve, although the raids were described as being across Portugal.
The Operation Predator team were told to look for Madeleine in the materials recovered. There is no specific detail of how they did this, nor of the capability of the PJ in checking. There is no mention of this material being sent to the US Operation Predator to conduct matching using their sophisticated capabilities, nor of any contact with CEOP. I will be writing an article in the near future on CEOP to examine what they could and could not do at that time.
Madeleine would have stuck out like a sore thumb from any Portuguese children in the cache of records captured in the raid, but I have no idea whether the were other pale skin white girls aged around 4 in the photos and videos.
This check did not provide certainty, but on the balance of probability, Madeleine was not swept up in Operation Predator.
In early October 2007, Paulo Rebelo took over the investigation into the disappearance of Madeleine McCann. He took a team of six PJ officers with him, all from Lisbon PJ. It seems likely that he did not wish his investigation clouded by officers who had been working the case before. Two of the officers Rebelo took with him were experienced in investigating paedophilia. Rebelo then did what Operation Grange has claimed to do. He started from afresh, re-examining from the beginning.
I have not found any follow-up media reports on Operation Predator, therefore I cannot say what happened to the 80 people arrested.