We never did find an anaconda in Peru, but on previous occasions I have captured 40 green anacondas in Guyana, Venezuela and Brazil, with five of 5.0m or more. However, trying to find a large aquatic snake in deep dark water is like trying to find a needle in a haystack so it was no real surprise that we failed on this occasion.
There are many giant anaconda stories in the Amazon but the largest anaconda on record is only about 8.0m in length. Many of the stories, including Ricardo's from Panna Cocha are based on the sighing of huge coils floating on the surface. From the vast girth of these coils the observer gestimates that the rest of the body, beneath the surface, is of similar girth, that the head is massive and the snake extraordinarily long.
However, the huge floating coils are much more likely to belong to a large but more modestly proportioned female anaconda that has recently fed. The gases released during digestion of a large prey animal such as a capybara or caiman will cause the skin to stretch to almost breaking point and these vastly inflated gas-filled coils will naturally float on the surface like an elongate tough-skinned balloon.
From the interviews we carried out on the Rio Huasaga and around Laguna Anatico I have no reason to believe there is an unnaturally large anaconda in the river or lagoons of the region and continue to be sceptical of any anaconda reports in excess of 8.00-10.0m.