We woke at dawn to the scene of a silvery grey light blanketing the high volcanic cliffs and calm waters of Denham Bay, our anchorage of the last few days on the west coast of Raoul Island. Once breakfasted, the team began their daily foxtrot of gearing up.
We must look a hilarious sight; some dousing in talc and squeezing into dry suits, others sailing overalls, booties and goretex jackets, with all manner of extra bits dangling from small tethers like hats, sunglasses, personal locator beacons, lifejackets clipped, headbands wrapped.
This, once layered with cameras, drybags, biopsy devices, GPS’, and other paraphernalia that we have around our necks and in our hands, makes it challenging to find one’s centre of gravity and hold on whilst pivoting and bouncing on a small boat, roughly 1/3 of the size of the animals we are encountering in 1-2m swells.
Nevertheless our skilful team has managed to collect 30 biopsy samples, deploy 11 satellite tags, record 7 song samples and snap around 2,000 images from which we have about 50 unique individual photo ID’s.
Male humpback whales sing a beautiful and complex song while in tropical breeding grounds and on migration. All of the males at each breeding ground sing the same song yet every year the song is different. The purpose of the song is also complex, with the main function being that it is to attract a mate. Interestingly, research suggests however, that singing males attract other males and in this way the song is learned and transmitted across the entire Pacific ocean basin, originating on the east coast of Australia and working its way eastward over time. For instance, whales in New Caledonia are singing a song this season which differs to that of the song in Niue; however they will have some themes in common as the song evolves.
One of my tasks on the expedition is to record these songs so we can match the themes to areas as another way of knowing where the Kermadec whales are coming from and going to. Whales also use a fascinating array of social sounds to communicate and we have been lucky enough to capture some of these as well as several long recordings for our database using an underwater microphone called a hydrophone, which is dangled about 20m over the side of our small boat. On the occasions of our recordings we pass the headphones around so each of the team can listen in real time to the symphony being conducted under water. The Kermadec seascape in early October is a very noisy place with whales whooping, squeaking, whistling and belching.
Today we have encountered a mother and her calf breaching simultaneously, while others, displaying courtship behaviour, stayed submerged for long periods. When our last whale today lifted up their tail flukes to dive, we saw lots of little black lines on it … A note of interest for some of the little people following our voyage (Hello Matisse and Aramis!), many of the whales we have encountered have evidence of killer whale attacks on their fins and backs. These can be identified by teeth marks which form lines that look like a rake has scraped it. Humpback whales scar white on their black pigment and scar black on their white pigment, thus the scars from the bite marks stand out distinctively.
Once back on the big ship from our long day on the water we scrub layers of sunscreen and salt off and hunker down to compile and compare our data. The crew of the Braveheart are looking after us very well and we collapse into bed exhausted, with a big smile, knowing that we are learning new things every day about a most magical, endangered creature in a most fascinating and isolated place. The work we are doing here is critical to the conservation of both.
By Olive Andrews