Shallow seamounts are “oases” and activity hubs for pelagic predators in a large-scale marine reserve

Our paper published in PLOS Biology “Shallow seamounts are “oases” and activity hubs for pelagic predators in a large-scale marine reserve” uses an integrated approach of BRUVS, seabird surveys, hydroacoustics, and satellite and acoustic tagging to study the effect of three unexplored seamounts on the pelagic communities surrounding them at Ascension Island in the remote south-Atlantic.

Fewer than 6 percent of the world’s seamounts are highly protected despite their recognised ecological significance. Many of the ocean’s top predators are declining due to human activities and there is a consequent and pressing need to protect seamounts which host a wide array of marine wildlife.

Our study shows that seamounts are thriving hubs out in the big blue, bursting with life. We found that these shallow seamounts are incredibly important for large pelagic predators, and that even those we think of as highly migratory are spending a significant amount of time around these features. Predator biomass at the summits was much higher than surrounding waters with a 41-fold enrichment of pelagic shark biomass and 10-fold increase in that of predatory fishes like tuna, sailfish, and wahoo. This enrichment was not restricted to predators but extended from zooplankton, through mid and high tropic levels and into the skies above the seamounts to seabirds. Combined, this evidence means that if we can target our protection efforts around shallow seamounts, we’ll provide better protection for those large threatened species like sharks and tunas.