Populations have fallen and in 2013, 11 of the world's 18 penguin species were assessed to be threatened with extinction by the International Union of Conservation of Nature's Red List.
A new study of all penguin species by experts concluded that degradation of the birds' habitats, pollution and fishing remained the biggest threats to the creatures.
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The research, published in the journal Conservation Biology, said existing threats needed to be tackled. Problems facing penguins include oil pollution, shipwrecks and vessels washing out oil tanks at sea.
Dr Phil Trathan, lead author of the study and head of conservation biology at the British Antarctic Survey, said: "Whilst is possible to implement large-scale conservation reserves, it is not always practical.
"However, there are methods that can help maintain a healthy ecosystem.
"For example, the use of spatial zoning to reduce the overlap of fisheries, oil rigs and shipping lanes with areas of the ocean used by penguins, the use of fishing methods to reduce accidental bycatch of penguins, and the use of ecologically-based fisheries harvesting rules to limit the allowable catches taken by fishermen."