Based on the images, the team was able to clearly identify the round fish nests, about 15 centimetres deep and 75 centimetres in diameter, which were made distinct from the otherwise muddy seabed by a round central area of small stones. Several types of fish nests were distinguished: “Active” nests, containing between 1,500 and 2,500 eggs and guarded in three-quarters of the cases by an adult icefish of the species Neopagetopsis ionah, or nests which contained only eggs; there were also unused nests, in the vicinity of which either only a fish without eggs could be seen, or a dead fish. The researchers mapped the distribution and density of the nests using OFOBS's longer-range but lower-resolution side scan sonars, which recorded over 100,000 nests.
The scientists combined their results with oceanographic and biological data. The result: the breeding area corresponds spatially with the inflow of warmer deep water from the Weddell Sea onto the higher shelf. With the help of transmitter equipped seals, the multidisciplinary team was also able to prove that the region is also a popular destination for Weddell seals. 90 per cent of the seals’ diving activities took place within the region of active fish nests, where they presumably go in search of food. No wonder, the researchers calculate the biomass of the ice fish colony there at 60 thousand tonnes.