Home on the Range

March 24, 2018

Ken Balcomb, Center for Whale Research founder and senior scientist, responding to the misconception that the Southern Resident killer whales (SRKW) are “resident” to the Salish Sea area, where they are seen most frequently by humans. 

 

Home on the Range

Where the Southern Resident killer whales roam and forage

 

It is naive to think that the Southern Resident killer whales  – J, K, and L pods – are only “resident” to the inland Salish Sea and that they depend primarily on Fraser River Chinook salmon stocks for their survival.

 

The SRKWs spent 86-95% (varies by pod and matriline) of the total days in 2017 outside of Salish Sea waters.

 

Where were they, what were they eating?

 

We know from Dr. Brad Hanson’s NOAA Fisheries satellite tagging studies a few years ago that L pod-tagged orcas spent a high proportion of time (when the tags were functioning) in the region of the Columbia River entrance. Hanson also collected Chinook salmon scales and DNA in whale feces in this area in the trail of the whales.

 

There has long been evidence that the Southern Residents travel up and down the west coast, as well as in and out of the Salish Sea, “cherry picking” the Chinook salmon, but never staying in just one location (e.g., at a major river mouth gorging on all of the fish). In my experience, the orcas travel with pulses of inbound spawners from coastal waters, through the Strait of Juan de Fuca and Haro Strait to Georgia Strait, then turn around and head back to or toward coastal waters. While inland, the whales travel at an average speed of 3.75 knots and cover about 75-90 miles per day, in relaxed foraging, mostly during incoming tides when the fish are moving toward the Fraser River mouth. They are always moving. However, as the biomass of Chinook per square mile diminishes, the whales spread out in smaller groups and appear more “busy” - attending to foraging rather than entertaining whale watchers. As a result of the Chinook fishery collapse in the inland region, the Southern Residents come into the Salish Sea much less often these days.

 

In the 1970s, the three pods that Dr. Mike Bigg identified in southern British Columbia waters were named J, K, and L (A-I pods were in northern BC waters), and they were discrete and separate enough for us to discern slightly different patterns in their distribution and association. J pod was encountered in Salish Sea waters in all months of the year and made forays into Puget Sound once or twice each month. The “Js” frequented Haro Strait; they passed through the strait every day or two from May through September when the seiners were fishing daily. From the seiners, we obtained a pretty good idea of how many salmon were heading toward the Fraser River, and from the test sets, we had an index of how many fish got to the river. It took us awhile, and much scale sampling in trail of the whales to figure out that they were targeting Chinook, even during runs of millions of Sockeye and Pink salmon. The scat sampling and the molecular data show the same pattern.

 

During big runs of Chinook salmon, K and L pods joined J pod in the interior waters, and in the late 70s and early 80s spent much of the May through September season going back and forth from coastal waters to the Fraser plume. We know for a fact they went as far out in the Strait of Juan de Fuca as Swiftsure and La Perouse Banks because a colleague, Brian Gisborne, photographed them out there whenever they were not with us in interior waters.

 

During a five-year period from October 2007 through May 2012, I posted more than 6,000 “wanted” posters in eastern North Pacific coastal marinas, on telephone poles, and in seaside business locations, soliciting sighting reports of killer whales and photographs of them. I received 7,217 sighting reports and analyzed them for SRKW pod identification. I followed up on fresh reports and “dead reckoned” the whales at 75 miles per day to position myself ahead of their travels, where I went to sea to photograph the whales.

 

The winter distribution (i.e., November through April) of all SRKW pods was preponderantly coastal from Washington State to central California, although J pod conducted occasional forays into the Salish Sea and Puget Sound in winter months. They have not been documented south of Newport, Oregon. My ID experts and I identified as many individual whales as possible in each sighting event and summed “whale days” spent in a broad coastal area (by state). A “whale day” was defined as one identified whale in a specific area, including the days required to travel to and through the area; and, if it was reasonable surmise to include additional whales were present, the additional whales were included (e.g., a matriline composed of five whales = five whale days). The results schematically were:

 

 Marine Mammal Science Note - SRKWWinter Distribution 20130209

 

There is no evidence to the contrary, either historical or as a result of the present studies, that indicates SRKW's might have a significant offshore distribution at times when they are not in inland marine waters. Thus far, the evidence for SRKW distribution in Canadian waters is consistent with this conclusion, but remains to be analyzed and reported (J. Ford, pers. Comm.). This continental shelf distribution should come as no surprise - the ocean productivity for these whales and their prey species is preponderantly coastal and inshore in the eastern North Pacific ocean (see SEAWIFS, NOAA). 

The satellite tagging studies of SRKW by Dr. Hanson showed much the same travel pattern and illuminated the model for winter months. L pod was most coastal in distribution, spending much time off Washington State, particularly in and north of the Columbia River plume; but, occasionally traveling for a week or so down to central California (Sacramento River/San Joaquin River Chinook salmon runs). K pod sometimes went with them, but in general seemed to range intermediate between L and J pods.

 

Because the SRKW must eat the equivalent of about 2.5% - 5% of their body weight pretty much daily, the coastal waters were and are important foraging areas for all three pods. In total, they probably eat as many as 580,000 twenty-pound Chinook salmon per year. I am sure that we could calculate the Salish Sea Chinook salmon contribution to the SRKW’s diet. The rest of their “catch” is coastal.

 

What is the take-home message from all of this?

 

The Southern Resident killer whales go where the Chinook are, looking for the energy-rich big ones. From the whales’ point of view, confirmed by distribution and foraging studies, the Columbia/Snake River Chinook salmon contribution is vital. We know from photographs taken as recently as last month that L pod was off Ocean Shores, WA.

 

It is just not reasonable to think that Columbia/Snake River salmon are not of importance to the Southern Resident killer whales. If the Snake River became a big, wild Chinook producer again, it would be an enormous benefit for the SRKW community. The Washington and Oregon coastal waters were proven to be recurrent distribution areas for the SRKWs during the study period cited above and are even more critical now that the Fraser River Chinook have collapsed.

 

One thing is for sure: The survival of the Southern Resident orcas will not wait for more United States and Canadian government meetings and scientific reports. Too much money has already been spent and is still being wasted. The salmon lost in years past should be evidence enough to convince decision makers that specific action needs addressing immediately.

 

 Photograph by Joey Winkler @weareanthro, anthro Films.


 

 

 

 

Please reload

Featured Posts

Restoring salmon runs, not politics, will save southern resident killer whales

July 17, 2019

1/10
Please reload

Recent Posts

March 24, 2018

January 30, 2018

January 6, 2018

Please reload

Archive
Please reload

Search By Tags