Scientists: Fishing boats compete with whales.

Two huge fishing vessels make their way through the icy waters of the Southern Ocean, passing among a pod of dozens of whales while slowly hauling on board bulging nets hundreds of meters long. The scene recalls a bygone era before commercial whaling was banned. Now, however, the vessels are not fishing whales but whale food: swarms of Antarctic krill (Euphausia superba), a small shrimp-like crustacean at the base of the Southern Ocean food chain.

“In the 20th century they used to follow large swarms of krill to help locate whales,” Matthew Savoca, a research scientist at the Hopkins Marine Station of Stanford University, told Mongabay. “And now potentially the krill fishery is doing the opposite, using whales to find krill.

In February, Savoca co-authored a  in the journal Ecology documenting a similar case that his co-authors had filmed a year earlier near Coronation Island, the largest of the South Orkneys. On that occasion, scientists encountered four trawlers fishing in the presence of what they described as a “remarkably large aggregation of foraging fin whales” numbering about 1,000 animals.

“This has been happening for years,” Savoca said. “It’s just what we were able to record. The point of the videos is alerting the scientific world that this is happening and will continue to happen, unless we change our policy about how we fish.