The Galápagos penguins are threatened by pollution, bycatch (the unwanted fish and other marine creatures trapped by commercial fishing nets during fishing for a different species), and climate change. Dogs can carry diseases that can spread to these penguins and cats are predators, posing a threat. These two animals are human introduced species, along with feral pigs and fire ants, all of which predate these penguins.
Furthermore, El Niño events in the past have caused mortalities of up to 77 percent. The term El Niño refers to a warming of the surface of the ocean, or sea surface temperatures being above average, in the central and eastern tropical Pacific Ocean. This heavily influences the Galápagos penguins populations as it makes the water warmer and makes their food less abundant. The cold-water schooling fish that are the main food of the penguins migrate away from the Galápagos islands during El Niño, causing food to become scarce. This has caused and can cause a drastic decline of prey species and reduced breeding success.
Another threat to Galápagos penguins are diseases brought by humans which the native species have no immunity against. Human traffic and fishing on the islands have also caused many penguin fatalities.