A scientific expedition in southern Chile has documented for the first time the larval stage of the icefish (Champsocephalus esox) in Bahía Inútil, on the shores of Tierra del Fuego. This unprecedented finding was obtained during a July 2024 sampling campaign that covered the entire water column down to the seabed.
The discovery provides a missing piece to understanding the life cycle of this species, the only one of its group that lives outside the Antarctic continent . According to the field team, the observation is part of a collaborative effort to characterize the bay's ecosystem using standardized and internationally comparable methods.
The discovery and why it is relevant
The specimen, measuring just 2 centimeters , was captured using a bongo net , a common technique for collecting zooplankton and associated fauna. After its identification, it was sent to the National Museum of Natural History of Chile for conservation and consultation by the research community.
The technical team emphasizes that having material from early stages facilitates taxonomic identification, since morphological changes during the development of bony fish can be significant. This new record will help refine diagnostic keys and comparative references for future studies.
The director of the Marine Program involved, Mathias Hüne , has highlighted that the larval record of Champsocephalus esox constitutes a substantial contribution to the knowledge of the diversity of Bahía Inútil and supports the monitoring of ecological trends in the area.
Who participated and the research framework
The campaign was spearheaded by Rewilding Chile's Marine Program , with participation from the University of Magallanes and the University of Valparaíso . The objective was to develop a comprehensive characterization of the system: from zooplankton and deep-sea communities to substrate-linked associations.
The set of techniques included the aforementioned bongo net, underwater robotic cameras , and dredges , allowing for the collection of comparable data on composition, biomass, and distribution. This multipurpose approach facilitates the identification of ecological patterns and potential human pressures.
A fish adapted to extreme cold
Icefish are famous for their adaptations to freezing waters, similar to those of other cold-water fish . Some species, such as Chaenocephalus aceratus , have translucent bodies , lack scales, and have colorless blood capable of transporting oxygen without hemoglobin.
Of the 16 recognized species in this group, Champsocephalus esox is the only one distributed beyond Antarctica . Its populations occupy the Strait of Magellan, Tierra del Fuego, the Beagle Channel, and the Falkland/Malvinas Islands, where the Yaghan people know it as “tsataki”.
Biodiversity of Useless Bay: data that had not been measured
The expedition compiled an unprecedented overview of the benthic assemblages in the area. More than 100 species of invertebrates, difficult to see with the naked eye, and nearly 150 categories of sediment organisms, mostly polychaetes—key to the recycling of organic matter and food webs—were identified. These findings connect with the work of invertebrate galleries in scientific institutions.
Communities associated with deep-sea habitats with high diversity and biomass were also described . According to academic Américo Montiel (UMAG), Bahía Inútil was among the areas with scarce information, and now has data on species richness , distribution, and biomass.
The area is used for harvesting spider crabs, mussels and sea urchins , so having reference series on the seabed will help to manage uses in a more informed way and to calibrate possible local impacts.
Threats and the need for protection
The ecosystem faces pressures such as overfishing , illegal dumping , and ocean warming , in addition to potential industrial projects. In 2023, the Forum for the Conservation of the Patagonian Sea identified this area as one of the macro-ecosystems with a low level of protection in the region.
For Champsocephalus esox, the trend is worrying: field estimates and studies point to a decline of around 30% over three generations . Therefore, the IUCN listed it as a vulnerable species in 2019 , reinforcing the urgency of management and protection measures.
With the first larval record now documented and a richer ecological base, the Bahía Inútil area gains arguments to reinforce its conservation , improve surveillance and guide public decisions with scientific support, something that the research community values and the management of the territory needs.
