"It just seemed obvious.."
Yes, they actually were catching blue cod from a hot tub. The Kiwitub in question was on Tim Wallis' deer recovery and accomodation boat "Georgina", moored in George Sound in Fiordland. And, yes, that's VERY fresh crayfish they're eating while waiting for a bite.
I do have reliable reports of duck shooters bringing down ducks from Kiwitubs hidden in maimais. No photos, as they feel it shouldn't be encouraged..