THE GUARDIAN, Pressemitteilung: ‚Really amazing‘: scientists show that fish migrate through the deep oceans

Open Access-Publikation im Journal of Animal Ecology:

New research has finally demonstrated what many marine biologists suspected but had never before seen: fish migrating through the deep sea. The study, published this month in the Journal of Animal Ecology, used analysis of deep-sea photographs to show a regular increase in the number of fish in particular months, suggesting seasonal migrations. Tracking fish in the deep sea is challenging. They are sparsely distributed, the water is nearly devoid of sunlight, and the monitoring equipment has to withstand enormous pressure.

The study used photographs taken by the Deep-ocean Environmental Long-term Observatory System (Delos), two observatories on the sea bed 1,400 m below the surface, off the coast of Angola. The researchers analysed 12,703 photographs – only 502 of which had actually managed to capture a fish – taken over seven-and-a-half years, and found that each year, in late November and June, there was a spike in the number of fish.

“It is certainly not unprecedented but it has never really been demonstrated,” says Rosanna Milligan, an assistant professor at Nova Southeastern University in Florida and the lead author on the paper. “That is what we were able to do with this study.”

“Even after all these years, one of my favourite parts of being a scientist is when you do those first graphs of your results and start to see something emerging from the data,” says David Bailey, a senior lecturer at the University of Glasgow and a co-author on the paper. “That’s one of the greatest thrills of the whole scientific endeavour. It was really, really amazing.”

Even with this new discovery, Milligan and Bailey still say there is a lot they don’t know.