He said McCaw had "one hell of a time" on the boat. "I almost wished I wasn't filming so I could enjoy it more. Not that you can't have a good time."
Although it was down time for the boys in black, there was no shortage of competitive spirit - and there were a few controversial calls. "They had to photograph the fish as proof, as we release the fish at sea, but some photos went missing," laughed Watson.
"There were accusations of players stealing each other's photos; rules were pretty loose."
Watson was coy when asked who caught the fewest fish.
But he said Aaron Smith had a "blinder". "He came away with a whole range of fish.
"He was the man of the match."
The episode featuring the All Blacks will be broadcast next year.
In Buenos Aires yesterday, McCaw was mobbed by young Argentine rugby fans as he was giving rugby tips. He was forced to abandon planned live television interviews.