A brief history of the Southern Residents
10 November 2014 - 5:37pm
WDC will be launching a new campaign soon and I’d like to offer a little background information so that our supporters have all the knowledge they need to help us out with our new endeavor.
Who are the Southern Residents?
We use that term a lot here, so I’d like to offer some clarification on just what we are talking about when we use the phrase. “Southern Residents” are the distinct group of fish-eating orcas that live in the Salish Sea and the coastal waters of Washington, Oregon, and California. These orcas are unique from other populations (both in the Northwest and worldwide), in their genetics, diet, vocal repertoire, appearance, behavior, and culture. “Resident” is the term used to describe orca populations that specialize on fish, because these orcas tend to stay in one area for long periods of time to take advantage of abundant food sources. In this case, the Southern Residents focus their foraging energy primarily on Chinook salmon, which can be up to 90% of their diet in the summer months. They mainly hang out in the Salish Sea (the inland waters of Washington and southern British Columbia, including Puget Sound) in the summer and early fall, but are more far-ranging in the winter and spring, traveling as far south as San Francisco, CA.
The Fraser River, as the largest salmon-producing river on the west coast, supplies most of the salmon for summertime. The Columbia (which is fed by other super-salmon tributaries like the Willamette and Snake Rivers), Klamath, and Sacramento Rivers are all utilized by the Southern Residents as they travel along the west coast in the wintertime, timing their arrival in these river outflows with the runs of adult salmon returning to their home rivers to spawn.
There is a Northern Resident population, too (hence the “Southern” for these orcas). Those whales stay mostly off the west coast of Canada and venture into Southern Alaska, and north of their range are the Alaskan Residents. Despite a small amount of overlap in range and a fierce love of fish, these populations are genetically distinct from each other, and interbreeding hasn’t occurred in thousands of years.
Both the Southern and Northern Residents are relatively small populations – Northern Residents (NRs) have approximately 260 individuals, and the Southern have only 78. The Southern Residents (SRs) are listed as Endangered in both the U.S. and Canada, while the NRs are listed as Threatened only in Canada. A dedicated census for each population occurs each year, and the tendency of Southern Residents to inhabit a highly populated area in the summer allows researchers to get a full count of the entire group every year. Every individual, every disappearance and death, and every birth has been diligently recorded for the past 40 years. We know a lot about this population and its history, and we know a lot about what is currently threatening their recovery.
In the 1960s and 70s, both resident populations were chased and captured for sale into the captivity industry. The SRs were heavily impacted, with at least 47 individuals captured or killed in the process. While the population has fluctuated since the mid-70’s, hitting a high of 98 in 1995, it has seen several periods of sharp decline, and recovery continues to be a struggle.
What are the current threats?
Thankfully, they’re no longer chased down to be sold into a short lifetime of misery in captivity, but there are some significant issues impeding the recovery of the SR population.
Prey depletion: Arguably the most important thing affecting these whales. Massive declines in salmon populations over the past 100 years have made it harder for the orcas to find food. When they have to travel more to forage, it burns into their energy reserves and they have less time to spend socializing, reproducing, and caring for young – all very important things to ensuring a population’s survival.
Pollution: Toxins and pesticides (including DDT, banned in the US in 1972) build up in fish and other creatures through the food web, eventually ending up stored in the blubber of the whales. Orcas in the Pacific Northwest are among the most contaminated marine mammals in the world – so much that stranded individuals qualify as toxic material. And if they can’t find enough to eat, the orcas start to burn through their blubber, releasing more of those stored toxins into their systems. These pollutants can impair immune systems and affect reproduction and fetal development – problems you don’t want to have in a population trying to recover.
Traffic: Tons (billions of tons, actually) of stuff is transported on cargo ships worldwide every year. Plus oil tankers, cruise ships, underwater construction, the Navy, fishing boats, and smaller personal and commercial vessels – all of them are found in the range of these orcas. Numbers of vessels are increasing, and so is the noise that they cause. A louder ocean makes it harder for these whales to communicate with each other and forage, and studies have shown behavioral changes in response to both noise and the presence of boats.
So their favorite food is already in short supply, and now they have a harder time finding it, causing them to burn up fat reserves that’s chock full of toxins – no wonder they’re having such a hard time bouncing back!
As part of my Rekos Orca Fellowship, I am focusing on threats to orcas in the Pacific Northwest and what WDC can do to help these populations. Mitigating these multiple threats and their compounding effects on these whales can be difficult – like swimming upstream, you might say – but there are many ways that we can help. And one way in particular, which we will share with you all soon :)