From the sea to the lab: the journey of a beluga carcass (2/3)

From Necropsy to Microscope

Last week, we tracked the journey of a female beluga from drifting offshore to the Faculty of Veterinary Medicine at the Université de Montréal. This week, discover the necropsy of a male beluga that was discovered on September 10.

A beluga necropsy is no trivial matter, and this exhaustive examination is is a case in point, as there are over 150 students on a waiting list to participate in the in-depth study of the organs and tissues of a representative of this endangered population. Apprentice veterinarians stand in awe before the lifeless whale, barely contained on the stainless steel table. In a few hours, only a skeleton with its organs exposed will remain. The objective is to shed further light on the health of the St. Lawrence beluga population and to discover the cause of death of this animal, obviously an old specimen judging by its size and worn teeth.

Measurement taking and external photos

The beluga carcass is one of the largest ever studied by the Beluga Carcass Recovery Network since it was first created in 1982. The beluga measures 4.75 m long and weighs 1.3 t. When it was taken out of the freezer where it had been stored overnight, the animal, suspended by the tail, touched the floor, a first for veterinarian Stéphane Lair, who began studying beluga carcasses in the 1980s.

After being careful to respect the numerous rules of hygiene in the room and avoid potential contamination of clothing and accessories, the whale must be measured: total length, half-circumference of the peduncle, stomach, neck, length of the genital slit, thickness of fat. These systematized data are used to establish, among other things, whether or not the animal is in good condition.

The candidate here is quite plump, notably due to the effect of putrefaction gases, but its 10 cm of blubber suggests that it did not die from a long illness but probably from an acute trauma. A sick or old animal that had long stopped feeding would have drawn from its fat reserves and would have been emaciated, which is not at all the case with our beluga.

Photos of the dorsal crest are also taken for submission to the Group for Research and Education on Marine Mammals (GREMM). The GREMM team strives to match photos of carcasses with those of living animals in the photo-ID catalogue. GREMM Scientific Director Robert Michaud would have hoped that the beluga would have evident markings or scars in order to add a chapter to the life of an animal he knows well, but Dr. Lair only notes subtle notches in the dorsal crest. To be continued!