Mussel and oyster cast-offs are an untapped industry for New Zealand, the founder of a biological byproduct company says.
David Magnussen, from Swiss company MBP Solutions, told the annual New Zealand Aquaculture Conference that crushed shells from mussels and oysters could become valuable soil fertiliser, especially for developing nations.
The shells are a source of lime from a pure type of calcium, which was going to waste, Mr Magnussen said.
It could become not only New Zealand's next export industry, but also a valuable aid programme, he said.
"New Zealand could ... help its own seafood producers manage a waste issue, which is apparently - from what I hear - unique, and at the same time help the salinity soil issues around the world.
"If there is government willingness and funding for such programmes, you solve two issues."
New Zealand was alone in exporting huge volumes of seafood without shells, he said.
Other countries exported shell and all, meaning the waste was distributed with the product.
The lime created in the process of a shell forming was more bio-friendly than lime from the ground, Mr Magnussen said.
"You can dig out lime from the ground and it is relatively cheap, but that is not a sustainable product."
Developing a new industry from shells was much bigger than a backyard solution and would need government input, he said.