Through several years of monitoring, the story of the “Luminosa” whale was revealed. It is a specimen of southern right whale, detected in the New Gulf of PenÃnsula Valdés.
Its record provides very relevant information about the species’ reproductive cycle. It is 30 years old and has a characteristic coloration that is hereditary, which led scientists to give her that name.
This is how the Luminosa whale is
This female of gray morph coloration is one of the members of the “Adopt a Whale” Program, by the Whales Conservation organization.
Luminosa is number 1193-94 in the catalog of southern right whales identified in PenÃnsula Valdés. She has been monitored since birth and has been registered in seven different years: in four of them, she was with a calf, which was born last year.
This time she was recorded in the San José Gulf in the company of a calf, also gray morph like her.
A whale that lights up the sea
Luminosa stands out for her gray morph coloration. When born, whales with this coloration are almost completely white and then turn gray starting from the first year of life.
This coloration is a hereditary trait: her calves are also gray morph or have gray patches on their bodies.
A curious fact is that more males are born with this coloration than females, due to its association with sex chromosomes, making Luminosa, being a female, even more special.
“When we see whales with this coloration just before they surface, they seem to illuminate the sea water from below, hence the name Luminosa,” highlighted the organization.
Luminosa whale: important data contributed to the research
Luminosa whale. (Photo: Nicolás Lewin).
Even though she could not be registered again during this last sighting, several characteristics observed indicate that she might have been pregnant. Among other data, they highlighted:
- The width-to-length ratio of the body is significant. Other females with these body proportions are later seen with a calf.
- The body width just behind the eye shows a thickening, attributed to a large fat reserve typical of whales close to giving birth.
- Also, there is a specific portion of the body that widens when they are pregnant, just behind the mid-body.
- The sighting was in June, the month with the highest number of pregnant females recorded in the Whale Measuring project.
Assuming Luminosa was pregnant, this adds valuable information about her life history. She has been recorded several times with a calf, but analyzing the intervals between the births in 2012, 2014, and 2018 raises a red flag.
Reproductive issues?
Southern right whales typically have a calf every three years: one year of gestation, the second of lactation, and the third to regain energy for the next pregnancy. “When a calf dies shortly after birth, its mother, who has hardly spent any energy nursing it, can become pregnant a year earlier than usual,” detailed the organization.
Thus, she gives birth again two years later instead of three. Other changes in the reproductive process can lead to intervals of four years. These are indicators of reproductive failures, “something we are increasingly observing in the PenÃnsula Valdés population,” they warned.
Moreover, from 2018, when she was seen with a calf, until 2023 (possibly pregnant), five years have passed.
Luminosa with her calf.
“This indicates that she probably lost a calf in between. It could also have taken her several years to recover an optimal body condition to become pregnant again,” they pointed out.
“Usually, the latter happens when there is low food availability in the feeding areas. Without records of Luminosa between 2018 and 2023, it is difficult to attribute any of these possible events with certainty,” they concluded.
