Last night, I had a conversation with Hans about the hydrophone recordings that Nienke and Jetske made on Saturday. He mentioned that the scientists that we've been working with suggested that some of the recordings may have been hourglass dolphins. I had no information on whether these tiny black and white dolphins ventured into the Ross Sea. Earlier on the trip, as we had sailed south from Auckland, a few hourglass had been spotted briefly at the Esperanza's bow, so we knew they were around, but much farther north.

But today, at around 63° south, they returned - for what was at least an hour! There was a bunch of brave sods out on the bow, braving the bitter wind - Gavin, Daniel, Arti, Isha, Celeste, Jetske and me. My eyes were streaming and my hands eventually started cramping - not from the cold, but from the effort of trying to track these rapid little guys as they darted around in the bow wave of the espy.

Hourglass dolphins are about 1.6m long, with two distinctive white flashes on either side of their black skin - giving an impression of an "hourglass" shape. They're poorly known and rarely seen, and according to Wikipedia, is apparently the "only cetacean to have been widely accepted as a species on eye accounts alone". By 1960, only three had been reported to scientists, and to date, "only 6 complete and 14 partial specimens have been examined". In the past, whalers hunting much larger whales, like fin whales, used hourglass dolphins as "look-outs" to aid them in their hunt. They live pretty far south - from 45° south down to the edge of the ice pack - so in terms of inhabited coastline, that really only covers the bottom of South America and the lower half of New Zealand's South Island. No wonder they're rarely seen.

Hourglass dolphins can swim at up to 12 knots, and after watching them today, they're one of the most manoeuvrable dolphins I have seen. They would swim alongside, streak past the Esperanza, then do rapid 180° turn and then vanish back the way they came before reappearing again on another wave.

Wikipedia: Hourglass Dolphin

- Dave