Salmon Steward

10 2018 psf.ca T here are two populations of fish- eating killer whales in British Columbia that dine almost exclusively on Chinook salmon. One of the populations – the Southern Resident Killer Whale – is frequently in the news because they number only 76, and appear to be nutritionally stressed. In contrast, their neighbours – the Northern Resident Killer Whales – number about 300 and are increasing, with no signs of food shortages. No one knows why the Southern Residents are doing poorly when pods from the Northern Resident community are doing so well. Some of the pods from the Southern and Northern communities have overlapping distributions, yet they are not experiencing the same change in numbers and body condition. One notable di…erence between the two killer whale populations is the amount of human activity that each experiences via commercial vessels, recreational boats, fishing and whale watching. WHAT DO SOUTHERN RESIDENT ORCAS REALLY NEED? Why are they in decline while their Northern neighbours thrive, and what can be done about it? THE HISTORY OF SOUTHERN RESIDENTS In the mid-1960s, prior to live capture for aquariums, it is believed that there were as many as 96 Southern Residents. By 1972, collections for public display had reduced the population to 72. Stopping the live removals helped the Southern Residents rebound to 98 by 1995. Unfortunately, populations have declined twice over the last two decades, with the most recent count at only 76. Since 1974, the Southern Residents have been censused annually using photo identification (see chart on the right). Southern Resident Killer Whales consist of three family pods called J, K and L. As of two years ago, the decline was limited to one of the three family pods in the population, while the other two haven't shown a marked increase. The Center for Whale Research reports that 40 have been born and survived in this population since 1998, but 72 also died or disappeared in that same time. By DR. ANDREW TRITES, Director, Marine Mammal Research Unit, Institute for the Oceans and Fisheries, UBC & DR. BRIAN RIDDELL, CEO, Pacific Salmon Foundation AN OVERSIMPLIFIED NARRATIVE Some people believe that the Southern Residents need a timeout from human disturbances — such as reduced underwater noise and less disruption while feeding and resting — while others put forth that fishermen need to leave more Chinook in the water for whales to catch. What is lost in this simple narrative is a broader recognition of what orcas once had, and how their world has changed. The territory used by the Southern Residents extends from Southern California to southern British Columbia. But the returns of large Chinook that these whales could once count on in the southern portion of their range are no longer there. The Elwha River, the "June Hogs" in the upper Columbia River, spring Chinook in the Snake River and winter Chinook in the Sacramento River – once fertile feeding grounds are all but empty. Instead, the Southern Residents appear to be increasingly reliant on Chinook at the northern limit of their range, where they likely compete with Northern Resident Killer Whales. They may also be competing with humans and other mammals that

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