Below you can read an hour-by-hour field diary entry Henley wrote about his humpback whale tagging mission in the Sea of Cortez off Baja California Sur in Mexico. “The SiR grant funds were instrumental in ensuring this research took place as we were able to facilitate logistics of boats and captains and fuel in a way which their own research budget could not meet,” says Henley.

Day 3

5:00 Wake and find batteries haven’t fully charged due to a power-cut and weak electrical current – this is problematic especially for the drone where I was already feeling squeezed for time with only 3 batteries. Eat breakfast in the dark as a purring cat sits on my lap and tries to steal it.

6:00 Drive to the bay and our boat.

6:20 We are on the water before sunrise but it’s overcast so magic hour light isn’t as spectacular as hoped. We find whales within minutes.

7:20 Find humpback whale mother and calf close to the coastline. These waters are a haven for calving, a time when the young humpback whale will guzzle up to 200l of milk a day.

8:30 For the last hour we have tried to slowly habituate the mother and calf to the presence of our boat to an allow an intimate approach necessary to place a tag. We make one last attempt and nearly pull it off, but not quite. We decide to move on as the circumstances are not quite right.

9:30 We listen to whale calls on the hydrophone and eat fruits.

9:50 We find a competitive group of males in pursuit of a single female. This is both very exciting to witness and offers the best opportunity for tagging as they will allow for a close approach.

10:40 Bag my first breaching shot! Breaching is primarily a social behaviour but it also aids in the removal of parasites and old skin. Seabirds quickly fly to the flattened water after a a breach and peck up morsels of food.

11:00 We get a tag on a male! This is the first time a CATs (customised animal tracking solutions) tag has been deployed in this area and the boat is buzzing with excitement. 

The next step is retrieving the tag, worth several thousands of dollars… it will release in about 2 hours but it could be more or less… once turned, the tag will provide a massive dataset including salinity levels, depth, gyroscope, hydrophone, compass direction. Olaf has also fitted a GoPro as additional bonus.

11:20 Start trying to take tissue sample from the tagged male with a crossbow and floating arrow system.

11:35 Successfully deploy arrow onto whale with tag. The sample is a couple of centimetres deep and a few millimetres wide, the impact will be barely perceptible for the animal. This biopsy sample will be analysed to provide information on molecular ecology, paternity, trophic level (feeding habits), testosterone and reproductive hormones, stress hormones, micro plastics, heavy metals, and there is even a technique to age the animal.

12:35 Super slow for the last hour and no sign of the tag releasing. We discover Esther only needs 2-3 hours sleep a night.

14:13 The tag is up at the surface, we know as we can hear clicking from the tag on a vhf radar. Now we follow the clicks in order to find it. The sea is glassy and overcast – perfect conditions for searching.

14:20 Good news as we find tag! Bad news: One of the four suction cups has been lost. Nothing is easy when it comes to operating with technology in the ocean, something I know well from photography and now realise also applies to marine research.

16:00 Start heading home only to see breaching humpback and go investigate – there are so many whales here at this time, it is clear evidence of the importance of this area to them and the need to protect it.

17:30 Back on shore.

17:45 Eat at fishing camp.

18:05 Leave beach.

18:30 Download data, photos, videos. Review and charge up batteries.

21:30 Sleep.