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On the Brink of Starvation: Southern Resident Orcas

The Pacific Northwest is home to a wide range of marine biodiversity. One species of whale in particular holds cultural importance to the stories and traditions of the Coast Salish people and is a favourite sight of locals and tourists alike. Southern Resident Orcas can be found in coastal waters stretching from British Columbia to Northern California. Off the coast of Vancouver Island, the Southern Resident Orca is one species of whale that can be seen on guided tours, swimming along the port or starboard of the Swartz Bay ferry, and even occasionally in Victoria’s Inner Harbour.

Southern Resident Orcas live in large extended family units called pods. The calls of Southern Resident Orca whales are unique to this species and can travel 10 miles underwater. The J Pod, the K Pod and the L Pod make up the three families of Southern Resident Orcas. During the summer, the critical habitat of these sea mammals spans the Salish Sea,[1] which includes the southern Strait of Georgia, Haro Strait and Juan de Fuca Strait. In the wintertime, they return to the central Puget Sound. Southern Residents are endangered due to human activities and the effects of Earth's changing climate. A large threat to the survival of these whales is starvation. As of 2019, the population of these whales stood at 73.[2] The Southern Residents have lost 7 adults since 2016 and have not had any surviving calves in 3 years.

Chinook salmon is the primary food source of the whales. These fish can be found spawning in freshwater areas such as the Fraser River, from where they migrate into the Pacific. In British Columbia, 8 out of 28 Chinook salmon populations are considered endangered, which creates a threat to the Southern Residents continued survival. Concerns surrounding the overuse and contamination of groundwater affect the salmon populations. When groundwater is drawn for human use and depleted, salmon have a hard time reaching their spawning areas to reproduce. Human activities can also have a negative effect on the temperature of groundwater and streams, which must remain stable to provide a hospitable environment for the fish.

Roughly 80% of a Southern Residents diet consists of Chinook salmon, and the average whale must consume approximately 385 pounds of fish per day. The Southern Resident Orca population as a whole must capture 1400 salmon daily to keep their population levels steady.[3] The declining Orca population can be attributed to the lack of prey relative to these energy requirements. Two-thirds of Orca pregnancies failed between 2008-2014 due to the inability of mothers to access enough salmon to eat. When Orca calves are born, their survival rate rests at 50%, and this rate is reduced when they are faced with a lack of adequate nutrition.[4]

The survival of many complex ecosystems, such as that of the Chinook salmon and the Southern Resident Orcas, are dependent on responsible water management. Foundry Spatial’s BC Water Tools make up one component of the solution towards promoting sustainable resource use by people and industries through the monitoring and reporting of the environmental flows of rivers, lakes and streams. The responsible management and monitoring of groundwater in British Columbia is a step towards long term environmental sustainability and conserving the ecology of the province.

Sources
[1] The Whale Trail
[2] Georgia Strait Alliance
[3] Center for Whale Research
[4] USA Oceana