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The Dam Difference for Fish

AIR DATE: Monday, November 10th 2008
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What does a new study say about the effect of dams on fish?

Environmental groups have said for decades that hydroelectric dams are a hazard for fish. Now, a new study calls that long-held claim into question. The study, published last week, tracked salmon and steelhead migrating to the ocean through eight dams along the Snake and Columbia rivers. It also tracked fish traveling out to sea via Canada's Fraser River, which does not have any dams. Scientists found the survival rate of fish migrating through the Columbia and Snake rivers to be higher than that of the fish on the Fraser.

Scientists and conservation groups are still debating how the new study's results should be interpreted. David Welch, the study's lead author, says the data suggests that ocean conditions could be more to blame than dams for the decrease in salmon populations. His colleague and fellow study author, Oregon State University professor Carl Schreck, says the evidence points to the strong possibility of unforeseen problems with the Fraser River.

What's your take on this surprising new study? What do you want to ask the scientists who worked on it? And does this most recent wrinkle in the Northwest's salmon saga change your relationship with rivers, fish, and hydroelectric power?

GUESTS:

Photo credit: poloballs / Flickr / Creative Commons

Tagged as: columbia river · dam · esa · fishing · salmon

Dams clearly make a difference! The obvious case in point is the plague of toxic parasites that breed in warm water behind the Klamath River dams. Not only fish but pets and people are being made ill.

A recent study that touts that the Frasier River in Canana has no worse salmon runs than the Columbia's is a very limited sample river, plus the lice that develop in fish farms along the Fraser are weakening wild salmon.

johndenton46 —
Anyone can access this article online and see in table one that the article is not comparing fish from the same years or sometimes even the same area of the river (take a close look at table 1).

Also, these tags are HUGE compared to the size of the fish that they are inserted into. I would imagine many fish died from the tag itself.

Finally, this article never mentions the adults that do or do not return. Hmmmm, I'd have to chalk this one up to poor self promotion on the part of a certain author (who owns the company that does this research).
Fish Head —
Surprisingly their is no mention of historic habitat inaccessible due hydroelectric projects on the Columbia and Snake Rivers (~25%). They also fail to address the amount of habitat altered/lost due to inundation by the other 13 dams with fish passage. But other than that the dams don?t appear to be ?major barriers to recovery in the Columbia?.
hansonjosh —
Let's use our heads and think about how ridiculous this study sounds. How can any rationally thinking person argue that dams are NOT a problem for migrating salmon.

Let's spend research money on some of the other reasons for the reduction of the salmon runs. How about looking at the massive amounts of herbicides that are continually dumped into our waterways. These chemicals effect the insects that salmon feed on and cause mutations all the way up the food chain.

Paul Cooke —
Why do we keep letting commercial and sport fishing on endangered species? Need to stop fishing for salmon immediately. It makes NO SENSE to try to recover a species so we can kill them and eat them.
Gadwall —
It sounds like the Frazier River fish are in real trouble too.
jkpete —
I would like to hear some discussion of the impact that industry and fishing has had on natural selection.

I have theorized for some time that fishing for example, removes the strongest fish from the stock. We do not have the means to determine the best genetic stock. Over time the quality of the genetic pool drops unnaturally impacting the survival of the fittest, and the passing of the strongest genetics to future generations.

Natural selection allows for the strongest to survive. Man's capabilities to deplete the stock is just so far ahead of what nature can do to keep up.

mysteryalias —
Sounds like you need to go do your own study. Otherwise check the ample existing data on this topic. Your worries will be alleviated.
Charlie 77 —
Feel free to share a resource. I would like to learn more as this is a topic I have not heard mentioned in salmon discussions.

I'll be surprised if my worries will be alleviated. But there is hope, if not for the salmon, for me.

Thanks.
mysteryalias —
Be happy to.
Broad or narrow? A particular river system? stock?
Charlie 77 —
Apologies.

Broad please.

Oregon rivers.

Thanks Charlie 77.
mysteryalias —
You can see the newer tags here:

http://www.kintamaresearch.org/tags.htm
David Miller —
One significant factor in comparing these survival estimates is the technology used to measure survival. Different technology is used in each river. In the Columbia, PIT tags, a little larger than a grain of rice are used. The acoustic tags used in the Frazer study are at least 2-3 times larger. Inserting the tag is likely to affect survival. This is known as tag effect. Given the large difference in sizes of tag, the tag effects are likely to be different. Other factors also affect survival estimates, including how easily the tags can be detected, etc. Another factor to consider is that we have many studies that have shown when you release fish on the upstream side of the dam and then recollect them below, a certain percentage will be killed or injured depending on the route of passage. So to say the dams have no effect is very misleading.
fishguy —
Just because research information doesn't support your view of how the world works, doesn't make it wrong or useless as long as the research itself is not flawed. It is a valid part of the whole picture and if you aren't willing to look at the whole picture, you will never be able to fix the problem or manage the resource.
katied —
If we are going to be serious about getting out of foreign oil use, then hydrogen is going to have to be a part of it.
When water spills over a waterfall or dam, some of it breaks into it's elemental properties of oxygen and hydrogen. In time this will prove to be the most cost effective way of capturing hydrogen for energy use.
Ridge
RidgeRider1320 —
I understand that a dynamic radio show needs some disagreement and tension. Still, I am disappointed at the way you have fashioned today's debate beginning with your title, opening sentences, and insistence on talking about the politics of to-dam-or-not-to-dam with the authors of the study.

The study's results are interesting, but even its authors repeatedly claimed that they were not out to study the effects of dams on the salmon population. You do a disservice to the scientific process and to the debate by stretching the study to try and fit into your topic.

christinavdk —
I'm one who did get sucked into the idea that the authors of the study concluded that dams were irrelevant to fish health, if what you wrote is true. I didn't hear the entire interview, and so I missed any disclaimers they may have stated.

So then I shot off the post below, which now seems a wee bit paranoic. Still, the whole wave of interest in the regional media seems fixated on the dam aspect, perhaps hoping we won't have to do anything. But then, the Oregonian supported McCain, so no surprise.

johndenton46 —
Correction: the Oregonian supported Smith, I mean.
johndenton46 —
The more you think about this study, the more it looks like the work of some geeks who tried out a cool device that they were able to plant in a fish, who then set out to measure fish survival in complex systems with all kinds of effects, but selected only one variable of the matrix--dams-- then drew conclusions that maybe dams aren't so bad, and got a lot of press.

This is the shoddiest piece of offal I've ever seen that's being passed off as science in this debate.

Irresponsible. But then, they'll keep their funding--the conclusions support the vested classes.
johndenton46 —
All science ends up in the political realm. I agree with Ed Backus' fear that this study has the potential to provide a distraction from addressing real long term recovery in the Columbia Basin. That may not be the author's intentions but it certainly gives the federal government something to hang their hat on. The grossly misleading press release title "No Dam Difference" doesn't help things either.

The Feds' last plan for the Columbia/Snake Basin rolls back many of the measures, like spill, that work for these fish. This PLoS study tells more about the unfortunate conditions of the Fraser River than the Columbia/Snake. The science on the Columbia has for years, clearly indicated that recovery to abundance of wild salmon and steelhead must include the option to remove the four lower Snake River dams. And that's science from state, federal, and tribal levels. Yet the federal government continues to ignore this reality.
sonicyouth —
Of course dams make a difference for salmon. To take one study and run to the conclusion that they don't, is completely irresponsible. For decades, scientists and hundreds of studies have pointed to dams on the Columbia-Snake River as the major source of salmon mortality ? killing upwards of 90 percent of juvenile salmon and steelhead. Nothing in the Welch study concludes otherwise.

What the study does show us is that the Fraser and Columbia Rivers are two completely distinct rivers that are both very much in trouble. Instead of wasting billions of taxpayer and ratepayer money on technical fixes like barging and trucking fish around dams and funding studies that search for a scenario that will let dams off the hook, I think it's time we accept the scientific consensus that some outdated dams ? like the four lower Snake River dams ? should be removed to recover salmon and restore a river. It's time to study how we remove these dams, restore salmon and make sure all affected communities make it out whole.
emilynuchols —
The study distracts from the big picture on salmon and dams: The Columbia River is no longer a functioning river (it is now a series of lakes) and has only 2-10% of its former salmon runs, for example the famous 'June Hogs' that ran up beyond where Grand Coulee dam is now are extinct. Chinook returns are currently 200,000 - 500,000 fish, a mere speck of the past runs. Read Jim Lichatowich's book Salmon Without Rivers for a compelling summary of this story. Also checkout www.stateofthesalmon.org if you want to see the level of our current knowledge and ignorance about the status of salmon on the Columbia and broader PNW and Pacific Rim.

We are at the point of marginal returns on the investment in trying to mitigate the effects of dams on the Columbia. Additional technological approaches will not bring any real improvements beyond what has already happened. The BPA has spent as of the mid 2000's about 3.3 Billion dollars on various approaches; trucking, barging, spilling, hatcheries, habitat restoration, but the real situation has not and will not change.

We should resist the take home message that technology will solve these issues or generate additionally useful knowledge beyond what we know to be the case in the macro picture. Read Richard White's (History professor at UW) book, the Organic Machine, for a succinct view of how humans have changed the Columbia through technology.

We should remove the dams on the Lower Snake River as part of a new energy policy that focuses on renewable energy sources. The Rand Corporation (2002) published a study that showed positive economic benefits in jobs and the general economy that would be generated from removing these dams. The work also confirmed that the lost power could be replaced by wind and solar. The NW Power Planning Council agreed with that finding on energy replacement.

Thomas Friedman in his new book - Hot, Flat and Crowded - discusses exactly why such an approach will constitute real leadership regionally, nationally, and globally. Those countries that figure out how to "green up" their energy systems will generate hugely positive economic and environmental benefits and attract investors and investment. There is no instrinsic reason that dams have to stay and pursuing a rational removal strategy (starting with the Snake as a careful process) will generate exactly the types of 3E benefits Friedman writes about - economic, environmental, and equity (social). We would greatly reduce impacts on salmon, generate new jobs, possibly recover some jobs in salmon fisheries, and attract new energy investments. Sure hydropower is "green" power, but its environmental effects are too great.

Specific issues with the study: 1) uses one year of data on the Columbia - thus there is no interannual variability in the work and this makes it hard to believe that it will stand up to broader peer review, 2) too many confounding variables - both the Columbia and the Fraser are impaired systems - this undermines the suggestion that the study is comparing a benchmark system with an altered system, 3) comparing hatchery vs. wild fish - the Columbia used hatchery fish from the lower Snake, the Fraser wild fish, again this is not a genuine comparison.

Let us not get distracted from the big picture.

ebfisheries —
I would like to clarify several incorrect comments in this posting:

1) ?Uses one year of data on the Columbia - thus there is no interannual variability in the work?.

Response: This statement is not correct. We measured survival in the Thompson/Fraser using acoustic tags in 2004, 2005, and 2006 (3 years). In the Columbia, we measured survival using acoustic tags in 4 years, not one: 2002, 2003, 2004, & 2006. We also compared these survival estimates with PIT tag estimates of survival for the 10 year period 1997-2006. (See Table 1 of our paper).

The only comparison presented in our paper that was based on only one year of data is the comparison of PIT and acoustic tag survival, which we showed was comparable in 2006. (We have now obtained the same result for more recent years).

2) ?too many confounding variables - both the Columbia and the Fraser are impaired systems - this undermines the suggestion that the study is comparing a benchmark system with an altered system?

The Columbia & Fraser Rivers are the two largest rivers on the west coast of North America and are, geographically speaking, relatively close together, and share a similar climate. We have never suggested that the Fraser was a pristine ?benchmark?. However, given that both have significant anthropogenic development on them our study may give some sense of what migratory survival might be like in a populated large river system with and without dams. While it would be interesting to compare survival in a pristine river system, such a comparison may lead to unrealistic expectations of how much salmon survival might be improved in either the Fraser or Columbia, as there are many other uses that the river is put to.

3) comparing hatchery vs. wild fish - the Columbia used hatchery fish from the lower Snake, the Fraser wild fish, again this is not a genuine comparison.

Response: This statement is not correct. Both the 2004 & 2006 Columbia and 2004-06 Fraser River studies used hatchery-reared spring Chinook; wild Chinook were not part of either study group.

All Steelhead used in the Thompson/Fraser River were of wild origin because hatchery-rearing of steelhead does not occur. In the Snake/Columbia the steelhead results are based on a mixture of hatchery and wild origin fish because the smolts were collected at either Lower Granite Dam or Bonneville Dams (see footnote C to Table 1 of our paper).

-David Welch
David.Welch —
In reading this study, I searched for confounding variables that might make the survival percentages of the Fraser River smolts appear to be lower than they really are. First, the researchers used tags that required large smolts to be used in the study. They could not use smolts smaller than 120mm and the V9 tags required fish to be greater than 140mm. These are fairly large for salmon smolts, and for reference an average spring Chinook smolt on the Warm Springs River in only 100mm long. There are plenty of published papers in existance supporting the idea that large smolts are more likely to become precocial than smaller smolts, and precocial smolts have lower survival than their non-precocial counterparts. If the researchers wanted to compare apples to apples in this study, they would have only used PIT tag data on smolts greater than 120 mm from the Columbia, but they made no mention of doing so.

Perhaps the most siginificant problem with the study is the placement of the final audio recording stations on the Columbia and the Fraser. In the Columbia they placed there equipment on the Astoria bridge which is just a few miles into the brackish estuary. However, the audio recievers in the Fraser were placed several hundred miles into the saltwater. I would guess there was a significant amount of mortality occuring considering the amount of saltwater the Fraser River smolts had to navigate before arriving at the location of their final detection array. I would have to argue that if the recievers were placed the same distance into saltwater on both systems, you would see drastically different results.

SpawnedOut —
I would like to correct an incorrect statement in this posting. All receivers used for reporting survival in the Fraser River portion of this study were located some distance upstream of the actual Fraser River mouth. In the Columbia River the receivers were placed in the vicinity of the Astoria Bridge in 2002-200, but in 2006 survival was measured to Willapa Bay, some 40 km north of the Columbia River mouth. Thus the situation is reversed from what the writer suggests, in that the Columbia River survival results are affected to some degree by early ocean mortality factors. This is not the case for the Fraser River results.

-David Welch
David.Welch —
Salmon

Listened to the salmon conversation on Monday and felt a little despair. There may be too many variables to effectively determine why salmon are not thriving. We need to keep studying to see if answers can be discovered but it feels like and expensive hunt for a few needles in hundreds of haystacks.

Perhaps humans have polluted and altered the environment too much. When do humans develop the sensitivity to work with nature harmoniously? Humans think they know so much, but are almost completely clueless to how the subtle and vastly interconnected natural systems really work.
trurl9 —
The results from this study rely heavily on the assumption that survival rates of acoustically tagged smolts are similar to survival rates of PIT-tagged smolts. To rigorously test this assumption, a reasonable scientist would release two identical groups of tagged fish (i.e., reared in the same location, having similar length, and subsequently releasing those fish at the same time and at the same place), and then compare their resulting survival rates to assess whether the tag type has had an effect. This type of comparison controls for potentially confounding factors such as temporal effects (changes over time), size effects (differences in survival due to length), location effects (differences in survival between locations), and rearing type effects (differences due to hatchery versus wild rearing), leaving the tag type (acoustic versus PIT) as the only variable that is different between the groups.

The description in Welch et al. (2008) gives the misleading impression that this type of controlled comparison was conducted:
"We first compared survival of PIT and acoustically tagged smolts in the impounded section of the Snake and Columbia rivers to assess survival of animals implanted with these different-sized tags in 2006 (Figure 2; [21]). Survival of acoustically tagged Snake River spring Chinook smolts from the Dworshak Hatchery stock (tagged and released at Kooskia Hatchery) was statistically indistinguishable from the estimated survival of PIT-tagged Dworshak Hatchery Chinook in 2006 (p > 0.05), demonstrating that the PIT and acoustic tag methodologies provide similar survival estimates for freely migrating smolts in the impounded section of the river."

I characterize this as a misleading description because the authors elected to omit several relevant facts about the significant differences between the two groups of tagged fish that they compared. First, the PIT-tagged fish were released more than a month earlier than the acoustically tagged fish (PIT: March 27 & 29, 2006 versus acoustic: May 1 & 8, 2006). Second, the fish were released at different locations (PIT: released from Dworshak Hatchery versus acoustic: released from Kooskia Hatchery, which is 60 km upriver from Dworshak Hatchery). Third, the groups of tagged fish were likely of different lengths because of the release timing (over a month earlier for the PIT-tagged fish), even if the researchers attempted to starve or reduce feed levels to slow the growth of the acoustic-tagged fish. Fourth, fish from all hatcheries, along with wild PIT-tagged fish were combined for estimating survival of PIT-tagged fish in the lower river (McNary to Bonneville Dams). The Dworshak-based survival estimates from release to McNary appear to have been appended to these combined, all-hatcheries/all-wild fish estimates for survival in the McNary-Bonneville reach for comparison to the survival of acoustic-tagged Dworshak Hatchery stock fish released from Kooskia Hatchery.

The comparison between acoustic- and PIT-tagged fish in Welch et al. (2008) thus appears to be deeply compromised by many potentially confounding factors: differences in release timing, differences in release location, differences in length at release, and differences in rearing type along with variation among hatcheries for the lower river survival estimates. Because the authors did not openly disclose these relevant facts, I have to question the honesty and integrity of each of the researchers involved, as well as the peer-review process that occurred with this paper, which should have brought these issues to the forefront. Without first conducting a properly controlled, rigorous, field assessment of the two tag types, the Columbia-Fraser comparisons are meaningless. A properly controlled, rigorous, field assessment of the two tag types did not occur. As a scientist, I am ashamed by the complete failure of the peer-review process to identify and raise these issues. Furthermore, I feel the Kintama Research corporation should be ashamed of itself for misleading the scientific community and the general public by misrepresenting, perhaps deliberately, critical and relevant facts about the groups used for comparisons in this research.
JoeSurfer —
An interesting point that is not discussed is similar tag effect studies have been conducted by the army corp of engineers research program. This research which compared Pit Tag survival to acoustic tags, the acoustic tags where smaller than the ones used in this study, revealed that there was significant survival difference between the two tags, it was not based so much on distance, but on time. This would indicate that the effects from the tags take a period to time to affect the juveniles. This effect would be somewhat muted since only larger fish were used. Smaller fish would show the impacts of tagging sooner than larger, so distance is not the best metric, rather time. Furthermore, larger fish tend to have better survival through the dams which would tend inflate the survivals.
This study is a proof of concept of the acoustic technology, which has advantages over Pit Tags which is the current gold standard, used in reach survival studies. Pit Tag are ideal for Smolt to Adult studies since they have minimal longer term effects and do not require batteries, they are also relatively inexpensive and can be used to tag large numbers of juveniles that incorporate the entire population size and not only available for larger fish. However, it is difficult to determine how and where the fish passed the dams and where they migrate. Therefore it is difficult to determine which management strategies are best for juveniles, ie does spill provide the best means of passage when compared to other routes of passage and transportation. These studies take many years to conduct. Where acoustic tags may prove invaluable is near dam passage, such that it will be know exactly when fish pass the dam, what route they took, how long they took to move through the forebays and tailraces of the dams. However, what is most needed for either technique is adult returns. Regardless of survival of the juveniles to the mouth of the river, if no adults return you still have not met success. Therefore you may have similar survivals between the two systems but have vastly different ocean survivals that may or may not have something to do with how they got through the rivers systems with and without dams. Lastly, just food for thought, the current Biological Opinion allow for 96% survival at each dam, when multiplied by 8 dams equates to survival rate of 72.14%, thus over of a quarter of the smolt population can be lost at just the dams, this does not include any mortality in the pools between the dams and mortality post Bonneville dam and to the estuary. So yes the dams do have an effect, the better question is, is it a limiting factor in the overall survival of salmon.
kelt10 —

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