July 20, 2019 - Gulf of St. Lawrence

Gulf of St. Lawrence

Swirls of green and teal floated in the Gulf of Saint Lawrence through July 2019. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of the scene on July 18.

Located in eastern Canada, the Gulf of St. Lawrence owes many of its unique characteristics to its geography. Only two channels allow saline sea water to flow into and out of the Gulf. The first, the Strait of Belle Isle, sits in the north and carries cold, Arctic water. In the south, the wider Cabot Strait admits warmer water from the Atlantic Gulf Stream. Numerous rivers carry fresh water into the Gulf, with the largest, the St. Lawrence River, bringing fresh water from the Great Lakes to the Atlantic Ocean via the Gulf. The flow from the St. Lawrence River helps drive the currents and circulation of Gulf waters.

In the springtime, the warming waters, lengthening daylight, and nutrient levels trigger phytoplankton, microscopic, plant-like organisms which live in these waters year-round, to reproduce rapidly, creating large blooms that can be easily seen from space. Phytoplankton form the base of the marine food web, helping to create a rich fishery in the Gulf of St. Lawrence. Blooms usually fade by late summer in this waterway.

The North Atlantic right whale is one of the important visitors attracted to the Gulf of St. Lawrence as the phytoplankton begins to bloom. The bloom feeds copepods, zooplankton, shrimp-like krill, and small fish, all of which provide nutrition for the enormous whales, which may weigh between 88,185 and 154,000 pounds (40,000 to 70,000 pounds). Classified as baleen whales, these whales feed by straining huge volumes of ocean water through their baleen plates, which act like a sieve to capture extremely small prey.

Heavily hunted in the past, the North Atlantic right whale, Eubalaena glacialis, is one of the most endangered whales in the world. The most recent North American right whale stock assessment report, published in 2012, counted only about 440 individual whales remaining. As they move from their breeding grounds in the Atlantic Ocean into the rich summer feeding grounds of the Gulf of Saint Lawrence, they face several dangers from human activity. Two of the most dangerous are “ghost” fixed fishing rigs that have been lost or abandoned, which can entangle the whales, and run-ins with the busy boat traffic of the Gulf.

This year has been very difficult for the North Atlantic right whales. In June, six right whales were found dead in the Gulf of Saint Lawrence. Three of those were confirmed due to collisions with boats. In July, three more right whales were discovered entangled in netting. Attempts are ongoing to try to free at least one of the entangled whales. The loss of nine whales out of a population of only about 440 in the world is a substantial loss. The Canadian government protects the right whale with reduced speed in the shipping lanes and rules regarding fixed fishing rigs, including mandatory report of lost rigs, as well as aerial surveys to locate whales that may be entangled or in dangerous shipping lanes.

Image Facts
Satellite: Terra
Date Acquired: 7/18/2019
Resolutions: 1km ( B), 500m ( B), 250m (1.1 MB)
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC