Hermaphrodism in a beluga whale

Beluga whale (Photo: Stéphane Lair)

The carcass of a large beluga whale (Delphinapterus leucas), weighing more than 880 kg, was submitted on May 27 at CWHC – Quebec Regional Centre for a post-mortem examination. This animal had been found dead along the shore of the St. Lawrence Estuary near Grandes-Bergeronnes, Quebec.

This animal had, on the skin over its right thorax, two long linear to slightly curved old cutaneous wounds that were almost healed. The wounds, which could have been caused by contact with the propeller of a boat, were associated with small pockets of infection deep in the underlying adipose tissue. One of the foci tracked down through the thoracic wall, allowing bacteria to colonize the thoracic cavity and cause a pleuritis (inflammation of the lining of the thoracic cavity). This lesion was chronic and associated with the presence of a large amount of fluid (approximately 50 L) and fibrin (inflammatory material / approximately 4.5 kg) within the thoracic cavity. This lesion is very significant and considered to have caused the demise of this beluga.

Another most peculiar finding was also noticed during the necropsy of this “believed to be a male” beluga: a female reproductive tract! Although this animal had the gonads/external genitalia of a male, ovaries and a uterus were also found in the pelvic area. A canal exiting from each uterine horn could be followed to an area located in the caudal portion of the penis, where they opened in the male urethra on its way to the urinary bladder. Although it does not appear this female genital tract could have been functional, the ovarian tissue will have to be examined under the microscope to evaluate functionality. Hermaphrodism is a very unusual finding in domestic and wild mammals. It is a condition in which an individual has both male and female gonads, usually ovotestes, i.e. a mix of both female and male reproductive tissue in the same gonad.

These anomalies of the reproductive tract are complex and usually require knowledge of three components for better assessment: chromosome structure, type of tissue present in gonad and type of external genitalia. Only six cases of hermaphrodism so far would have been recognized in marine mammals. Three of those reported cases are actually St. Lawrence beluga and two are actual true hermaphrodites, i.e. having the reproductive tract and gonads of both sexes. The cause of these reproductive anomalies remains unclear. However, the presence of three cases of “intersex” in the small population of St. Lawrence beluga is very unusual and suggests potential predisposing factors. Even if speculative at this time, the link between this and the known exposures of beluga to endocrine disrupting chemicals should be questioned.

We have to commend the hard work of Carl Guimond from Filmar and of the Parks Canada team for the very challenging recovery of this carcass on the rocky shores of the Côte-Nord.

Beluga whale found dead on the shore of the St. Lawrence Estuary (Photo: CWHC Quebec regional centre)

Submitted by André Dallaire, CWHC Quebec