Scientists Find Evidence of Deep-Sea Fish Migration Route

The DELOS platform during maintenance.

The DELOS platform during maintenance.
Photo: Nova Southeastern University

Marine biologists have found clues to a previously undetected deep-sea migration route more than 4,500 feet below the surface of the Atlantic, according to a new article.

The deep ocean is a huge and mysterious biome; 80 percent this has not been charted to this day. Scientists hope to better understand the ecology in this region, especially as oil and gas activities drill into deeper water. A new study of a large international university collaboration has found photographic evidence of deep sea populations that change seasonally, a sign that these fish are migrating elsewhere.

This data comes from time-lapse photos taken between February 2009 and July 2016 from two stations of the Deep-ocean Environmental Long-Term Observatory System (DELOS), both located off the coast of Angola; one is 50 meters from an oil well. The researchers counted how many fish were in each photo per day over the 7.5 year period, according to the article published this week Journal of Animal Ecology.

The analyzes showed a seasonal pattern of the amount of fish observed in both observatories. Not only that, but the abundance of fish seemed to be correlated with the overall chemical energy of organics on the surface of the ocean; the deep sea fish peaked about four months after the peak in biological activity on the ocean surface—about the amount of time it would take the carbon to descend to the sea bed.

Fish photographed by DELOS.

Fish photographed by DELOS.
Photo: Milligan et al (Journal of Animal Ecology (2020))

For the time being, this study presents only early proof of a migration route, and theIs unclear where the fish actually goes. But the team hopes for much more. The DELOS platforms will work with the experiments for a total of 25 years, and the team wants to gather more information about the connection between energy on the surface and the fish below.

It is important work. “We don’t have many long-term studies in the deep ocean,” Rosanna Milligan, the study’s lead author and an assistant professor at Nova Southeastern University in Florida, Gizmodo said. “That is starting to change, but it is also increasingly important. Most human effects are effects that last from months to years, if not much longer – given climate change, over decades or centuries. With this data we have these longer time series. ”

This knowledge is also important in brief-term effects, especially related to oil and gas activities. Oil and gas companies are going to drill in deeper watersbut scientists have no data on the consequences of their drilling operations animals that live in depth. For example, the Deepwater Horizon drilling rig rented by BP was in 4100 feet of water exploded in 2010, causing the biggest oil spill in history. But scientists still don’t understand the long-term consequences of this ecological disaster.

Knowing that deep-migrating sea fish, as well as where they migrate, would be critical to efforts to to protect them from destructive human activities.

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