Why is Seattle’s Orca Whale Population Dwindling?

Jenah MacGrain |
An Orca Whale in the San Juan Islands. Image: San Juan Islands

Pods of Orca whales that are famous for appearing in Puget Sound, WA are disappearing at an alarming rate. The pods, named J, K, and L,m normally see 4 or 5 calves born each year, however in the last 3 years not a single calf has been born. The Seattle whales are seeing a 30-year low in population numbers, with only 75 orcas still remaining. In the late 1990s, the pods included nearly 100 whales.

Scientists are attempting to understand the rising mortality rate, but whales are difficult to study as their corpses either sink or wash up and are hard to find. According to a New York Times article, researchers have many concerns and ideas of contributing factors that may be leading to the loss of these creatures.

Pod of Orca Whales. Image: Loubet-Modelisme

Years ago, theme parks captured a large number of these Orcas which shrunk the gene pool, and experts are now seeing sings of inbreeding that are causing a weakening of the population. Females are reproducing every decade as opposed to every 5 years and some are not reproducing at all- researchers are worried that the reproducing females will age and die, and will not be replaced.

Pollution in Puget Sound is another cause for concern. The lingering effects or chemicals and pesticides suppress the whales’ immune systems, making them more susceptible to disease. Scientists do state that the decline in these specific pods cannot be fully blamed on pollution however, because pods in more polluted areas of the world are thriving.

Puget Sound. Image: Los Angeles Times

Researchers have recently started looking at fatal human or animal diseases crossing the species barrier and affecting the whales, who are already immune-compromised. If a highly infectious virus came in contact with the pods, it would destroy a large part of the population and most likely put an end to recovery efforts.

The expansion of the Trans Mountain Pipeline is a new threat to Orcas, increasing oil tanker traffic and excessive noise. The increase in commercial traffic in the ocean also adds to the increase in noise, and in a growing city like Seattle, is hard to avoid. This noise can cause hearing loss, as well as interfere with the whales’ echolocation, making it hard to communicate and locate prey. Construction of the pipeline will begin in August.

Chinook, or King Salmon. Image: GeekWire

The disappearance of the Orcas’ main food supply, the King Salmon, is one of the more prominent factors scientists are considering as the reason for the dwindling PNW Orca population. In fact, this reason put the entire species on the Endangered Species list in 2005. The researchers are aware that it is most likely a combination of these factors causing the decline in the whale population. The Times article describes a possible scenario, which includes several of the above factors, that may be leading to the shrinking numbers. Due to lack of salmon and increased noise, the whales are starving. Their bodies then draw on fat reserves, which are laced with chemicals from water pollution. These chemicals suppress the immune system and reduce fertility.

In March, Washington Governor Jay Inslee issued an executive order calling for state agencies to do more to protect the whales, and in May, he created the Southern Resident Orca Task Force, a group of officials with the goal of figuring out ways to stop the loss of these animals. Maintaining the population of Orca whales in one of the fastest growing cities in the country will be a difficult task, but the Task Force is willing to help in any way possible.

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