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Friday, October 3, 2014

Southern Residents and Chinook Salmon: An Undeniable Link

As another summer whale-watching season winds down here in the San Juan Islands, it's an appropriate time to reflect on how these whales are doing. Last year, we had an all-time low in both salmon numbers and whale visits to inland waters, that left many of us wondering what this year would bring. There was an undeniable sense of relief that we had the Southern Residents around a lot this year- no more stretches of days and weeks without whales as we experienced in 2013. Still, despite some proclaiming that this summer was "just like the good ol' days", it really wasn't. While the number of whale days spent in inland waters was certainly up, the amount of pod-fractioning hit an all-time high. We had different groups of partial pods around on almost a daily basis for a while. Yes, there were whales around to watch on most days this summer - but often it was a group of a dozen or twenty whales, rather than 40 or 50 whales or all 79 together in a superpod (by my unofficial count, we only had all matrilines of all three pods in inland waters at the same time on three days this summer). Additionally, while we celebrated the birth of L120 this summer, we also experienced yet another year where deaths outnumbered births, and L120's arrival ended the longest drought in births ever documented, with 25 months having passed since J49 was born.

So, to put it simply: this year was better, but all is not well.

Average Albion catch per unit effort (CPUE) on the Fraser River for Chinook salmon for June 1 through August 31 from 1980 to 2014. Here I'm using the average CPUE as a metric for how many salmon are returning to the Fraser River during the summer months, when Fraser Chinook are the predominant prey item for Southern Residents. From this graph you can see that 2014 was the best year of the last four (fish hatched in 2010 returned this year), but that numbers are still severely depressed from historic counts.

Not surprisingly, the number of whales we see in inland waters is directly (and significantly) correlated to how the Fraser River Chinook salmon are doing.
Number of whales in inland waters (considered east of Sooke, BC) from June 1 - August 31 of this year compared to same-day Albion catch per unit effort (CPUE) numbers for Chinook salmon on the Fraser River. There is a statistically significant correlation between these two variables (ANOVA, p = .01)

Finally it seems that, at least among the general public, salmon is the hot topic issue surrounding these whales. In the past, attention has focused on proposed vessel regulations or controversial research techniques, but now more than ever it seems like people are being educated about, and are talking about, the fact that the age-old adage is true: no fish, no blackfish. With this increased attention on the issue that really matters, NOAA has been under further scrutiny as the agency that is tasked with developing and implementing a recovery plan for the Southern Residents as part of their listing under the Endangered Species Act.

This spring there was an orca and salmon recovery workshop in Seattle, which I attended. Perhaps the most astonishing thing to me was the apparent lack of communication between the so-called "whale people" and "salmon people". Several of the salmon specialists who spoke mentioned how exciting it was to be talking to someone different - namely all the people present who were there from the "whale side". I had heard about the phenomenon of scientists working within the "silos" of their particular disciplines or sub-disciplines, but never was it more apparent to me than at that workshop. Here we have two species whose recovery plans are undeniably interlinked, yet it seemed like the two groups responsible for those species weren't working together. I'm certainly paraphrasing here, but the message I heard from the orca management side is that when it comes to the prey recovery portion of the killer whale recovery plan, they defer to the salmon recovery plan. And the folks representing the salmon recovery plan basically said, "We do nothing to take killer whales into account."

But maybe I should back up a little bit. Is the link between Southern Residents and Chinook salmon as obvious as I think it is? It is now common knowledge that Chinook are the predominant prey item for the resident orcas, making up more than 90% of their diet during the summer months. Evidence from a small number of prey samples in the winter also indicate that Chinook remain an important food source year-round. But when I attended a lecture this fall given by NOAA management, they made a statement that floored me: there is no evidence that survival or recovery of the Southern Residents is more strongly linked to any particular Chinook salmon stock than to a coast-wide Chinook abundance index. They recognize a correlation that has been published by John Ford linking Southern Resident population numbers to a coast-wide Chinook abundance index, but again haven't found links between Southern Resident life statistics and any particular salmon runs.

I should take a moment to say that I do not have anything against NOAA. I believe the people there are passionate about these whales and their recovery, and they have done a lot to add to our knowledge of these whales - for instance, the information on year-round Southern Resident diet comes from work done by NOAA scientists. But their hands are also tied, to some extent. They have to try to balance pressures from multiple interest groups when working on recovery plans, and they only back up any recovery measures with scientific data. Just like how we all "knew" Southern Residents were spending the winter months on the outer coast, we couldn't prove it until they were satellite tagged - and that hard data proves instrumental for things such as keeping these whales protected when NOAA is petitioned for their de-listing, as happened in 2013 by a group of California farmers. So it was shocking to me that what I assumed was an undeniable link between Southern Residents and Fraser River Chinook apparently has not been demonstrated scientifically, which is what I heard from the NOAA management.

I took this as a bit of a personal challenge. Working with a friend of mine, Reed College student Michael Weiss, we created some spreadsheets of data to test out my assumptions about the relationship of Southern Resident survival and Fraser River Chinook. Here's what we found:

NOTE: These are not complete or perfect statistical analyses and should not be taken as such. These are first-stab attempts at looking at these numbers by biologists who are not mathematicians. These results have not been reviewed or endorsed by anyone.

1. The Fraser River follows different trends than coast-wide salmon numbers.
Coastwide Chinook salmon abundance (including California, Oregon, Washington, British Columbia, and Alaska) is indicated in blue and referencing the left Y-axis. This data was compiled by Jane Cogan from Pacific Salmon Commission and Pacific Fishery Management Council reports. The orange line indicates Fraser River terminal run size (including spring, summer, and fall Chinook runs) and references the right Y-axis. This data was also compiled by Jane Cogan using NOAA Technical Memorandum NMFS-NWFSC-123 for 1980-2010 and Pacific Salmon Commission data for 2011-2013. There is not a statistically significant correlation between coast-wide Chinook abundance and Fraser River terminal run size (ANOVA, p > .05).

2. Southern Resident Killer Whale birth rates are significantly correlated with summer Fraser River Chinook numbers; birth rates are not significantly correlated with coast-wide Chinook abundance.

Southern Resident Killer Whale birth rate compared to average Albion CPUE for June-August from 1980-2014. Birth rate was calculated from Center for Whale Research data as number of births per number of reproductive females per year, where a reproductive female was defined as any female between the ages of 11 (youngest documented mother) and 42 (oldest documented mother) who did not have a calf the previous year. There is a statistically significant relationship between birth rate and June-August average Albion CPUE (ANOVA, p = .026).

3. Southern Resident Killer Whale death rates are significantly correlated with coast-wide Chinook abundance; death rates are not significantly correlated with Fraser River summer Chinook numbers.

Southern Resident Killer Whale death rates compared to coast-wide Chinook abundance from 1980-2013. Death rates were calculated from Center for Whale Research data as number of deaths per total number of whales alive at any time during a given calendar year. Coast-wide Chinook numbers were compiled by Jane Cogan from the sources mentioned above and cover California, Oregon, Washington, British Columbia, and Alaska Chinook stocks.. There is a statistically significant correlation between coast-wide Chinook numbers and SRKW death rate (ANOVA, p = .020)

Additionally, it is important to mention the recent publication (August 2014) of a peer-reviewed paper by L. Antonio Velez-Espino et al. in the journal Aquatic Conservation entitled "Relative importance of chinook salmon abundance on resident killer whale population growth and viability". You can read the abstract here, where with proper permissions you can also download the complete paper. This study compares resident killer whale survival probability and fecundity rates to Chinook salmon abundance partitioned by geographic region and found some similar results: significant relationships between Southern Resident killer whale fecundity and Puget Sound and Fraser River salmon abundances, and significant relationships between more coast-wide metrics and survivability. I should point out that this paper conducts more robust statistical analyses than are undertaken in this blog post, including taking population age-structure into account when measuring fecundity and survivability. (This is important, because 40 year old whales aren't as likely to give birth as 20 year old whales, and 70 year old whales are more likely to die than 10 year old whales. What is key to note is that with these more accurate tests, they come up with the same general conclusions.)

Velez-Espino et al. went on to conduct population viability analyses for the Southern Residents under different management scenarios, manipulating potential restrictions or allowances of fishery harvests to determine if fishery management could potentially have large enough impacts on salmon abundance to influence Southern Resident survivability and fecundity. They conclude that the interaction effects of fisheries management on Southern Resident vital rates are small and that restricting fisheries may not be an effective management action.

At first glance, I could see this seeming to some like an outrageous statement. Certainly managing fishing to allow there to be more fish for the whales should result in the whales being more likely to survive. But this may in fact not be the case - recall that the scientific panel convened by NOAA and DFO several years ago came to the same conclusion, that regulating fisheries wouldn't help Southern Residents. Here's why: 

There aren't nearly as many fish as there used to be.

Historic Chinoook salmon numbers (as presented by Jim Myers of NWFSC from sourced dated between 1880-1920) compared to present (2012 data from Pacific Salmon Commission and Pacific Fishery Management Council reports compiled by the author) Chinook salmon numbers for several major west coast rivers and regions. Klamath River historic data averages two different conflicting reports.

For the most part, Chinook salmon numbers are a small fraction of what they used to be. And fisheries only harvest a small percentage of current salmon returns. This means that when we're talking about the number of fish being taken by fisheries, we're talking about a pretty small number of fish, especially relative to historic salmon levels. Taking this into consideration, I don't think it's surprising that fisheries aren't projected to have a large enough impact on the number of fish available to the whales to impact their viability at a population level. While restricting or closing fisheries would result in more fish for the whales, I think what these analyses really tell us is that it still wouldn't yield enough fish. We need to do something more, something bigger, to recover salmon numbers.

So, where do we go from here?

I wish I had all the answers, but I don't. As I've learned more about regional salmon issues, I've learned how amazingly complex the issue is, transcending international and state boundaries, multiple special interest groups, public and private land management, etc., etc. However, I hope that going forward we can acknowledge:
  • The viability of the Southern Residents is linked to particular salmon stocks
  • Salmon numbers are too low, even when the phenomenon of "shifting baselines" leads to the heralding of "record" salmon runs
  • Managing fisheries alone isn't enough to yield enough fish for the Southern Residents
  • Something big needs to happen to help boost salmon numbers
The need for action can't all be laid on NOAA's shoulders. The Fraser River is admittedly out of their jurisdiction. While there is a petition pending to extend Southern Resident critical habitat to include the outer coast, the fact of the matter is the designation of critical habitat doesn't do anything to support recovery or replenishing of resources within that habitat - it only instigates that future permitting within the critical habitat must consult the endangered species recovery plan. I've come to believe that they simply don't have the tools on their own to instigate the kind of efforts we need to see happen. While I hope they do play a major role in regional salmon recovery efforts on behalf of the whales, we, as concerned citizens, can't just sit around and wait for that to happen. This article is meant to help ignite the conversation of what we can do to help make sure that it happens.

One perfect opportunity to be a part of the ongoing discussion comes later this month. On Saturday, October 25th at Friday Harbor High School, The Whale Museum and the Salish Sea Association of Marine Naturalists are hosting a workshop on this exact issue. What can we do to make sure real action gets taken to help boost Chinook salmon numbers for the particular stocks that are vital to the Southern Residents? I hope to see you there.

[Disclaimer: I was not asked by any group or person to compile this information, do these analyses, or write this article, nor did I receive any compensation of any sort for doing so. I am simply a concerned citizen trying to do my part to discover why these whales are declining, figure out what I can do to help, and inspire others to do the same. Additionally, the statistical tests here have not been peer-reviewed and should not be considered perfect analyses by any means. They should be taken as best efforts by two non-mathematicians and hopefully a starting point for future discussion.]


Vera said...

Wow! What more can I say?

Julie said...

i agree with your mom... that is an excellent post/article. you are extremely articulate in explaining the issue of salmon and orca populations and using data to reflect critical correlations. well written, monika! and i'm glad you put it out there. it's time for discussion to begin!