Salmon producers are hoping to reduce the impact of fish farming on the environment by changing how they feed their fish.
It's part of research being undertaken in Nelson where thousands of king salmon are being carefully monitored by scientists.
Waste from fish farming can damage the surrounding area, starving the seabed of oxygen and killing off life in the most extreme cases.
"If we know the nutritional requirements of the king salmon species, they'll eat less as a result. That's a lesser impact of the environment and a better outcome," said Grant Rosewarne of New Zealand King Salmon.
There's still much to learn about king salmon, with new studies underway at Cawthron Institute's new $8 million finfish research facility, housing 4,000 king salmon to improve their species' breeding, growth and diet.
Even the impact of the weather is being measured. Last summer's warmer sea temperatures were linked to more salmon deaths.