Giant Deep-Sea Skate Nurseries

A remarkable discovery

On deep-sea volcanic summits, nearly 1,600 metres beneath the surface, millions of skate egg cases blanket the seafloor. This extraordinary nursery concentrates generations of developing skates onto a remarkably small area of an underwater volcano (seamount).

The nurseries are dominated by Pacific White Skates (Bathyraja spinosissima), one of the deepest-living and largest skates in the world. Arctic skates (Amblyraja hyperborea) also reproduce here, but Pacific White Skate egg cases are roughly twice as large and outnumber them by about four to one.

Meet the skates

A large white female Pacific White Skate is centred in the frame swiming in the water column above corals on a seamount. Her underside is visible and bright yellow egg case is sticking out of her cloaca.

Pacific White Skate

(Bathyraja spinosissima)

A grey mottle female Arctic Skate swims brushing just over the seafloor and coral on a seamount.

Arctic Skate

(Amblyraja hyperborea)

Why here?

Dense skate eggs ranging from yellow to black are distributed in crevices of fractured basalt. There's some orange mineral precipitate associated with venting around the rock bases.
Skate egg cases are visible in crevices with small patches of orange precipitate with exception of Pacific White Skate Egg Cases within a vent orifice coated in orange precipitate.

The eggs are not randomly distributed—they are concentrated around the shallowest summits and areas of geothermal activity. Warm seafloor, diffuse hydrothermal flow, currents and the seamount’s volcanic setting may together create exceptional habitat for developing embryos.