It is fair to say that Southern Clams Limited has one of the most beautiful web site's out there - with some exquisite photography.
This is from their website:
In the 1980s, inspired by anthropology studies and an interest in food as a cultural resource, Roger Belton, had a vision to sustainably harvest native shellfish from selected areas in Otago and to take the delicacy to the food plates of the world. After years of practical hard slog and reflective research to develop sustainable management systems for both the shellfish and its habitat, Roger’s company Southern Clams has carved out niche markets in Europe and North America (servicing demand in a place where there is a strong tradition of clam cuisine) to become a thriving southern business that Otago can be proud of.
I guess I've always called them cockles - in the states Clams - a marketing thing.
My favorite was to serve clams/cockles is - steamed - and with lemon wedges.
Contact details are here:
PO Box 483 Dunedin . fax: 0-3-479 2698. Call Free:0800 771 505