For the second year in a row, Mowi, the world's largest farmed salmon producer, topped the Coller FAIRR Protein Producer Index, making it the most sustainable protein producer among 60 of the world's largest publicly traded protein-producing companies.

A total of four aquaculture companies made it into the list's top 10. The ranking assesses companies against 10 Environmental, Social and Corporate Governance (ESG)-related criteria, including greenhouse gas emission levels, deforestation, antibiotic use, animal welfare and working conditions, among others.

The Coller FAIRR Protein Producer Index examines 60 protein producing public companies with a combined market capitalization of $338 billion (€286 billion).

Strong performance in antibiotics put Mowi and Bakkafrost in the lead against the rest of the consumer-facing protein producers.

The index is meant to enable and support investor decision making "at a critical time for sustainable investment."

The majority of meat and dairy suppliers on the list (86 percent) still rank as high risk on greenhouse gas emissions, with 35 percent showing annual increases in emissions.

"Whilst this landscape for investors remains challenging, for the factory farming industry it presents the perfect storm for innovation," said Jeremy Coller, FAIRR founder and chief investment officer at Coller Capital.

"In fact, it is forcing them to make changes as investors watch closely to determine who fails to rise to the challenge and who takes full advantage of this opportunity."