The Series Of Peripartum Mortalities Continue in Female St. Lawrence Beluga Whales.
On July 17, 2012, the carcass of an adult female beluga whale was found drifting by the island of “l’Ile aux fraises” in the St. Lawrence Estuary in Quebec. This carcass was transported to the CCWHC – Quebec for a full necropsy. The only significant gross finding observed in this female was the presence of a very large and asymmetrical uterus filled with blood indicating a very recent calving. The absence of other significant anomalies, and the good body condition of this whale, suggests that its death might be associated with complications during the birthing process. Full histological and toxicological evaluation will need to be done in other to fully exclude other possible causes of death. This is the second stranded female beluga whale that has died shortly after giving birth (postpartum) this year. The first animal, found stranded on May 19 of this year, died of a full blown peritonitis (infection of the abdominal cavity) centered on the uterus. It is believed that this peritonitis was a consequence of uterine lesions caused by a difficult labor. Obviously, the newborn calves of these two females did not survive.
These two cases were the sixth and seventh female St. Lawrence beluga whales that died peripartum (either just before or after giving birth) during the last three years; two cases of fatal dystocia (difficult labour) were documented in 2010, and three were found in 2011. The cause of the apparent cluster of peripartum mortalities is currently under investigation. Potential risk factors include increasing contamination with endocrine disrupting toxins such as polybrominated diphenyl ethers (a persistent orgainic pollutant), and increased exposure to saxitoxins produced by harmful algal blooms. Ongoing monitoring of calf production and of causes of mortality should help to determine whether this problem is transient or a new significant issue threatening recovery of this population.