This past week a news story was released confirming the death of the newest member of the Southern Resident Killer Whale population, a seven-week-old calf. The new calf, L120, born into L-Pod at the beginning of September, was the first birth into the Southern Resident Killer Whale population in over a year. Sadly, scientists confirmed the calf had passed away after three confirmed sightings of its mother L-86, also known as Surprise, was seen without her calf. When an Orca is born, it spends the first year of its life almost directly beside its mother due to its requirement to be nursed several times an hour. Therefore, seeing the female Orca without its two month old calf multiple times has led to scientists’ theories that it has passed away.
Listed as endangered by the U.S. Fish and Wildlife Service in 2005, the Southern Resident Orcas are the smallest population of Resident Orcas in the eastern North Pacific. Currently, this population totals 78 members, even less than their population in 2005 when they were first listed as endangered. As a result of their long life span and slow maturation, female Orcas on average only reproduce every 4-8 years. Furthermore, of those calves that are born into the Southern Resident population, approximately 45% of them actually survive. This shocking statistic is unique only to the Southern Resident Killer Whales (SRKW), and is a result of two major threats: Chemical contaminants and declining food source.
Although they may look healthy and magnificent on the outside, the SRKW population is majorly endangered due to pollutants and toxins in the water. Run-off from rivers near large cities, such as Vancouver and Seattle, is causing devastating effects on these mammals. Toxins such as PCBs (poly-chlorinated biphenyls) used in transformers and electric motors, and PCDDs (Poly-chlorinated dibenzodioxins), a byproduct of chemical manufacturing using chlorine, are polluting the waters around Washington and British Columbia. Although PCBs were banned in the 1970’s in both Canada and the United States, some third world countries still use them today, and they can still be found in the water and soil around our area. The Southern Resident Orca population is believed to be one of the most contaminated groups of Orcas in the world. These Orcas feed on large salmon that come into the Strait of Juan De Fuca in order to reach the rivers to spawn during the autumn months. In the rivers, the salmon feed on zoo plankton and other particles in the water that contain these pollutants as a result of runoff. These toxins accumulate in the fat layers of the fish, which in turn get eaten by the Orcas. All of the toxins contained in the fish are then stored in the blubber layers of the Orcas, resulting in a multiplied accumulation of these chemicals, a process known as bio accumulation. Although the small amount of chemicals one fish may contain would not harm an Orca, after decades of feeding on these salmon the amount of toxins stored in their bodies can start to cause physical harm. Pollutants such as PCBs have been found to suppress immune systems, affect reproduction, and have even been linked to causing cancer. In addition, they are particularly harmful to young calves which are nursing on their mother’s milk for the first year or two of their life. During this time, female Orcas produce milk for their young offspring which is made up of about 30-50% fat. The fat she uses to produce this milk comes directly from her blubber, which contains all of the toxins she has been storing for the first few decades of her life. As a result, these toxins are passed directly from the mother to the calf through her milk, having a devastating effect on the newborns who are not equipped to fight these chemicals. This is one of the major reasons why the survival rate for young Orcas is so low.
In recent decades, overfishing has become a major issue and concern for the west coast of Canada. Overfishing is not only a key concern for our ever growing human population, but also for large marine predators such as Orcas, which play important roles in the marine food web. Although each subspecies of Orca generally has a distinct diet, starvation has become a particular problem for many of the Resident Killer Whales, not just for the population here in the Pacific Northwest. In addition to overfishing, problems such as habitat degradation due to clear cutting, salmon farms, and pollution, are destroying streams where salmon spawn, further reducing the major food source for our Orcas. Recently, the decline in Chinook salmon in our area has become such an issue for the Southern Residents that noticeable signs of malnutrition have been observed in the population. This, in combination with high toxin levels can result in very harmful effects for these Orcas, as malnutrition in mammals already fighting off diseases due to chemical pollutants is an accumulating negative effect.
The headline of the seven-week-old Orca passing away this week is disheartening news for the Southern Resident Orcas. These whales have a long journey ahead of them, fighting for their lives from chemical pollutants and a decline in their main dietary source. Today, young Killer Whale calves have an even tougher journey ahead, surviving the first few years of their life. However, with the continued support of influential government and non-profit groups, these whales will hopefully have the greatest chance of becoming a survival success story!