A study of the blue whale in the Gulf of St. Lawrence indicates alarmingly low calving rates for the endangered species, the Sierra Club Canada says.

The organization says the non-profit Mingan Island Cetacean Study has followed blue whale populations in eastern Canada, the Sea of Cortez and in the waters of Iceland for the past 35 years and has identified 475 individual whales.

The study says that population has only produced 22 calves.

The Department of Fisheries and Oceans estimate there are fewer than 250 adult blue whales left in the northwest Atlantic population today.

Female blue whales can calve every two years if external factors allow, Mingan group founder Richard Sears says, adding that the exact cause for the low reproduction rate found in the study remains a mystery.

The Sierra Club recently launched a campaign to safeguard the blue whale's habitat in the Gulf.