The promise and perils of Antarctic fishes

Beneath the surface of the Southern Ocean, in the deep waters of the continental shelf and continental slope of Antarctica, a magnificent fauna consisting of over 320 known species of fish thrives in the cold and dark. These fish are uniquely adapted to the extreme environment in which they live. Over the course of millennia, they have evolved a remarkable range of physiological and biochemical features, the most visually stunning of which is that some lack haemoglobin (Fig 1). Yet, these species are under threat from global climate change and fishing, and the secrets they might unlock for science could be lost in the next decades if action is not taken. Figure 1. The blackfin icefish Chaneocephalus aceratus . Photo credit: Steve Untracht. A human can survive in freezing water for around 15 min before their organs begin to shut down. The fauna of the Southern Ocean spend their entire lives at these extreme temperatures. The fish species present are dominated by members of the Notothenioidei, which comprises 50% and 90% of the Antarctic finfish diversity and biomass, respectively [1,2,3]. The notothenioids are a suborder of perch‐like fishes that are mainly benthic and highly endemic to the Antarctic region. They are divided into eight families that have radiated from an ancestral stock during the last 20 million years to fill a variety of niches. These families include the Nototheniidae—the most diverse and specious family of the notothenioids—the Bathydraconidae—the dragonfishes, so‐named because of their especially long and narrow body forms—and the Channichthyidae—the icefishes, known for their colourless blood. > …the Antarctic and its spectacular fauna are suffering a fate similar to others on the planet—their survival is threatened by anthropogenic activities The composition of today's Antarctic fish fauna has been strongly influenced by the distinctive oceanographic features of …