The most extensive and densely populated breeding colony of fish anywhere lurks deep underneath the ice of the Weddell Sea.. The 240 square kilometers of regularly spaced icefish nests, east of the Antarctic Peninsula, has astonished marine ecologists. “We had no idea that it would be just on this scale, and I think that’s the most fantastic thing,” says Mark Belchier, a fish biologist…

In February 2021, the RV Polarstern—a large German research ship–came upon thousands of 75-centimeter-wide nests, each occupied by a single adult icefish—and up to 2100 eggs…High-resolution video and cameras captured more than 12,000 adult icefish (Neopagetopsis ionah)….The  team on the RV Polarstern saw 16,160 closely packed fish nests, 76% of which were guarded by solitary males. Assuming a similar density of nests in the areas between the ship’s transects, the researchers estimate that about 60 million nests cover roughly 240 square kilometers.

The vast colony, the researchers say, is a new reason to create a marine protected area in the Weddell Sea…The Weddell Sea—a unique and largely undisturbed ecosystem—is already protected from a destructive fishing practice called bottom trawling…

Excerpt from Huge Icefish Colony Found, Science, Jan. 14, 2022