New Zealand long-finned eel is sold as pet food in the United States.
Researchers for the Manaaki Tuna group have been looking into who's buying the eel here and overseas with the aim of promoting a consumer boycott.
But they never imagined the threatened species would be ending up in the cat bowls of California.
Addiction Foods of Te Puke exports a range of gourmet petfoods, and markets them in the US and elsewhere as earth-friendly and hypoallergenic.
It uses only the best of wholesome wild protein - opossum, kangaroo, vension and salmon. Also what it calls "unagi" or "wild and delicate New Zealand eel - from New Zealand's pristine streams and lakes."
Addiction Foods says its Unagi and Seaweed Entree is rich in Omega fatty acids and ideal for dogs with allergies.
Massey University freshwater scientist Mike Joy says the problem with that is that the allergic dogs or cats are fine-dining on a threatened species.
He is one of a number of researchers calling for a moratorium on the harvesting of longfin, which is New Zealand's only endemic eel.
Manaaki Tuna says long-fin numbers have been in decline for decades and the species may be approaching extinction.
But Addiction Foods says it's relying on New Zealand Government advice that eels in this country are harvested sustainably:
''The eels used in our products are managed under NZ's internationally respected Ministry of Fisheries Quota Management System,'' it said. ''This reassures us as we know that the numbers of eel are carefully monitored and sustainably harvested."
The Ministry of Fisheries - now part of the Ministry for Primary Industries - says that's correct.
It says long finned eels are a commercial species, sustainably managed under the quota system - and as such they may be used as an ingredient in petfood.
The ministry says catch limits are reviewed periodically in light of the best scientific information: for instance in 2007 the catch limit for North Island long fin was reduced from 193 tonnes to 81 tonnes.
The ministry says eels are protected by a range of restrictions besides the quota system and commercial fishing is banned in national parks and reserves.
Manaaki Tuna says it will now target overseas buyers of New Zealand eel to let them know they and their pets are consuming what the Department of Conservation classifies as a species in decline.