Men of Science Speaketh on Behalf of Striped Bass

[matt johnson]

Instead of preaching to the choir, I thought I would post this over here for all the haters!

Check out the link:

http://californiawaterblog.com/2011/01/31/striped-bass-control-the-cure-worse-than-the-disease/


Matt

[Darian]

Nice to see a objective/reasonable statement by a respected scientist on this subject.... :D

[FlyReelFisher]

Interesting read.

I am glad the point of restoring the environment supercedes the diversionary tactic of blaming solely striped bass.

Largemouth bass, I agree are probably more pernicious to the survival of juvenile salmonids.

How they know the predation rate on hatchery versus wild juveniles, would be good to know.

Interesting argument that stripers may keep other invasives in check.

Unfortunately, the desire for a "tug" might contribute to the defeatism concerning the possibility of wild salmonid population restoration. Maybe if the whole(whole!, I know some are) "save the striper camp" fought to remove ALL the dams on delta tribs, it might help.

Don't let them devide and concur us, don't give in/give up.

[BillB]

Now that's an interesting article! I have always supposed that habitat degradation is exponentially more damaging than fly fishers, fishers and/or stripers. Seems there is more than one striper-less river that may indicate such.

[Covelo]

Nice to see a objective/reasonable statement by a respected scientist on this subject.... :D

Darian, were you being sarcastic with that statement? Yes it was reasonable but objective it was not. Certainly the point that the system is a lot more complex than just stripers and salmon and steelhead is valid, and of course we should be pursuing restorative actions for the habitat, but there was a little too much speculation to call it objective. Stupid hatchery fish buffering predation on wild fish??? Really? Unlikely even after they have already driven down the wild fry numbers by bullying them and out competing them for space and food. Their artificially large size gives them a huge advantage from predation and in competition. To not take action because of speculation that it might be worse is not scientific and leaves the status quo which we all know is not good enough. The DFG should have action plans to limit the numbers of all exotic species.

[Darian]

Nope!!! I wasn't being sarcastic. I suppose I could've chosen my words better. The article is probably more along the line of editorializing/re-assuring us (the fishing public) more than a detailed, factual analysis. At any rate, I didn't see any harm in it. It's not likely to be used to support much of anything. :)

[Don Powell]

Bennett and Moyle have seen a lot and know a lot.
The experienced fishermen who taught me what I know, have seen a lot and know a lot.
I have seen a little and know less.

This perspective is to be heard and respected... "food for thought" one might say...

[Bob Laskodi]

Well said Cov, and DR Moyle is indeed being used by the "pro striper" lobby as a mouthpiece for their special interest position, just like the "water barons" have their PHD's espousing "science" for their "special interest" position. I have already seen those referenced quotes (several have no basis in actual studies and are merely his opinion) forwarded by the "pro striper" groups as the "truth in science" (as the OP suggested), so his words are indeed being utilized for political purposes and are not objective, but highly biased. I suspect the actual truth lies somewhere between the water barons political position of "stripers are the devil of the Delta" and the "pro striper" groups political position of "stripers have no significant impact on salmon populations" (and both of those positions are highly manipulated with political rhetoric and both are basically false).

[Covelo]

No doubt the authors know a lot and are widely respected. That is why it was surprising to read so much speculation in their comments. Scientists usually do not do that. They hypothesize then structure experiments to test their hypotheses. Presumptions are or should be uncommon.

[Darian]

It must be difficult for a UC-Davis Prof/scientist to be a spokesperson for the "Blue Ribbon Task Force" on the Delta. Trying to communicate what's going on without losing your audience can't be easy.... Apparently, Dr. Moyle is doing it well.

[Darian]

Trying to communicate what's going on without losing the audience can't be easy.... Apparently, Dr. Moyle is doing well.

[Bob Laskodi]

"That is why it was surprising to read so much speculation in their comments. Scientists usually do not do that."
Yep, I was quite surprised by that also. Especially from DR Moyle. I expect that kind of baloney from the water barons minions, not university based scientists. Hopefully, this was just a one time mis-step in his objectivity meter.

[Darian]

I've re-read the article a couple of times now and can't see where it was intended as a scientific paper. IMHO, this is no misstep. The intended audience appears to be the public. Why would we expect Moyle or the co-author to make a scientific presentation in that forum :?: :?: Not everything Moyle and his co-author says/writes outside of the hallowed halls of UCD is going to be technical....

Remember, Moyle crossed over into the political world by accepting appointment to the Delta Blue Ribbon Task Force which was populated with local politicians and headed by State Senator Steinberg at the direction of the former Guv. This may be nothing more than an Op-Ed piece....

[OceanSunfish]

The intended audience appears to be the public. Why would we expect Moyle or the co-author to make a scientific presentation in that forum :?: :?: Not everything Moyle and his co-author says/writes outside of the hallowed halls of UCD is going to be technical........

I agree.... I forwarded the document to family and friends who appreciate being kept informed of the issues regarding water, fish, ecosystem, etc.

The way the ariticle was written was inviting for the "public" to read, and most importantly, finish reading....... Best of all, these folks came away with greater awareness, which is what we all would like to see, right?

[Covelo]

I did not look at it as a scientific paper either. That was not the crux of my point. Dr Moyle is a scientists and scientists generally avoid speculation even in non-scientific forums. Here are 3 examples from the article.


Striped bass feed heavily on juvenile salmon and steelhead in the rivers. However, most salmon eaten are likely to be fish from hatcheries that are poorly adapted to the wild. High predation on them has little bearing on the degree of predation encountered by more wary juveniles from natural spawning. Predation on hatchery-reared juveniles may even buffer wild fish from such predation, given that wild fish are warier and less conspicuous than the more abundant hatchery fish.

Does he really believe that hatchery juveniles are lowering the predation on wild juveniles? Based on what. That is pure speculation. It ignores that hatchery juveniles are much larger and typically out compete wild fish. At Van Arsdale on the Main Stem Eel, there was a complete inversion in the hatchery to wild fish ratio with predation by the introduced Sacramento pike minnow, suggesting that the complete opposite is true. That hatchery fish, at least those that do not get picked off right away, are better at surviving piscivorous fish. Further, if stripers are eating all these salmonids in the river, as the article concedes, then won't their populations be rising since they are getting all this food dumped on them by the hatcheries? I do not see how more stripers in the rivers is better for wild fish. Lastly, it is as if Dr Moyle is stating that hatcheries are good for the wild fish since the juveniles that are released protect the the wild fish from the stripers that feed heavily on them in the rivers. That is just backasswards!


If the striped bass is indeed the dominant predator on other fishes (the reason for a control program), then their decrease should have the most impact on species that are most frequently consumed. The ‘release’ from predation by striped bass is highly likely to benefit many other alien fish that are also known predators and competitors on endangered fishes. For example, Mississippi silversides are important in the diets of 1-3 year old striped bass, so bass predation may be regulating the silverside population. Fewer striped bass could result in greater silverside numbers, which may have negative effects on delta smelt through predation on eggs and larvae.

If this happens, then this may happen which could lead to this which may cause this. Yeah that was scientific.


Reducing the striped bass population is quite likely to have a negative, rather than positive, effect on the species a control program is supposed to protect.

Quite likely?? Really? I agree with their premise that the system is so screwed up that tinkering with it might have unintended consequences, but to actually come out and suggest that one outcome in this incredibly complex system is "quite likely" is complete bias talking.

[Don Powell]

Thanks guys for contributing to my understanding of how politics and true environmental issues mix so poorly...
You have brought a lot of understanding and quite frankly, much sadness to this entire debate.
But it is to be predicted in our ever more populated and more politically factioned world...
Glad I'm alive now to enjoy what remains of the natural world- as we grow and become even more divisive, the environment shall surely be the victim!

[Darian]

I can't find anything in your examples to disagree with and concede that some scientists don't engage in speculation in a public forum but certainly not all. Those that don't risk losing the attention of their intended audience (the public). This article is evidence that at least two UCD scientists do engage in some level of speculation at times and for a particular purpose to communicate.

Since we're in agreement about the speculative content of the article (it's like an op-ed piece), we can also conclude that the article contains bias. What op-ed piece doesn't :?: :?: That doesn't change my level of respect for their knowledge and/or work....

[Covelo]

Those that don't risk losing the attention of their intended audience (the public).
Not entirely sure what you mean by this sentence. Interpreting though, a scientist can explain complicated concepts to the public in basic terms without going past what can be supported.


Since we're in agreement about the speculative content of the article (it's like an op-ed piece), we can also conclude that the article contains bias. What op-ed piece doesn't That doesn't change my level of respect for their knowledge and/or work....
I do not accept that this is like any other op-ed piece since the authors put the full weight of their positions behind it, essentially saying believe us we know what we are talking about. They even list their full titles at UC Davis. This article does not change my level of respect for their knowledge and/or work either, but I think it reflects poorly on their stature, especially as objective researchers. It will also make me skeptical of any future position they present to the public.

[Darian]

What I meant in that sentence was that presenting scientific or highly technical information to the general public is likely to be a lost cause as the audience will eventually tune them out. While I agree that scientific information can be presented basically enough to be understood to an audience of limited size and interest (such as fisherman, etc.), I'm not sure a wider audience would be receptive or care at all.... Guess I'm just too cynical about "the public" at this point.

I've been judging the style of the article against recent articles in the Sacramento Bee and San Francisco Chronicle newspapers on similar articles. It seems to fit into that mold given the length, etc.

[STEELIES/26c3]

To play devil's advocate...

I (and others on this board...) have arrived at many similar conclusions without a scientific study...

Having even a nominal understanding of ecological principles, it is rather easy to see truth in the following statement:

If the striped bass is indeed the dominant predator on other fishes (the reason for a control program), then their decrease should have the most impact on species that are most frequently consumed. The ‘release’ from predation by striped bass is highly likely to benefit many other alien fish that are also known predators and competitors on endangered fishes.

Based on numbers alone, of course this is very likely.

OK so not proven with empirical data.

Big deal?

Scientists are allowed REASONABLE AND EDUCATED speculation aren't they?

You ever take a statistics or cladistics course?

Is that science?

The works, discoveries and breakthroughs of many of our greatest geneticists were founded in educated guesses (probabilities)....

Not really pushing any agenda here but I think Moyle should be allowed to generalize once in a while without drawing heated criticism.

and I'm not just saying that because I love steelhead AND STRIPERS~;) and agree that reduction of stripers would likely result in greater numbers of pike minnows and therefore.... yada yada yada

[matt johnson]

From what I have observed, I would say that most fisheries science/management that applies to the Central Valley/Bay/Delta is based on varying degrees of speculation. The system is simply too complex, and in such constant flux, that absolutes do not apply very well. But, I guess I am speculating on that point!

On another note, I've personally always speculated that striped bass predation on salmonid juveniles falls heavily on hatchery releases, since wild juvenile rearing is largely separated in space and time (there are no stripers crashing scools of fall run juveniles in the Sacramento in Redding right now, trust me on this). In contrast, the majority of Central Valley hatchery fish are annually released at the same places and times low in the system where stripers are abundant. This is an idea based on facts and speculation!

I'd like to see if the current diet/predation studies on striped bass are going to take a look at the origin of the salmonids (if any) found in the stomachs. Genetics? Looking for coded wire tags? However, I don't know if these studies are well enough funded to go into that much depth. Bob, do you know? Matt

[Bob Laskodi]

"On another note, I've personally always speculated that striped bass predation on salmonid juveniles falls heavily on hatchery releases, since wild juvenile rearing is largely separated in space and time (there are no stripers crashing scools of fall run juveniles in the Sacramento in Redding right now, trust me on this). In contrast, the majority of Central Valley hatchery fish are annually released at the same places and times low in the system where stripers are abundant. This is an idea based on facts and speculation!"
Whilst predation does occur heavily on hatchery fish due to the way releases are conducted, hatcheries are now experimenting with a variety of release protocols to help lessen predation issues. However, tracking of acoustic and RF tagged fish, which are released in a different manner, do show very significant predation rates. The release protocols for tagged fish are very strict and includes releasing in low light conditions, release at multiple dispersed locations, release of small quantities of fish, and a whole bunch of other requirements. Many of these release protocols were developed for the sole purpose of reducing predation on the tagged fish (they are too valuable to be "wasted" on predation studies). So it is not speculation that significant predation occurs on salmon and steelhead smolts outside of the mass hatchery releases.

"current diet/predation studies on striped bass are going to take a look at the origin of the salmonids (if any) found in the stomachs"
At this point in time, the studies that I'm aware of are only looking at identification of species consumed and the amount of consumption.

[Bob Laskodi]

"I do not accept that this is like any other op-ed piece since the authors put the full weight of their positions behind it, essentially saying believe us we know what we are talking about. They even list their full titles at UC Davis. This article does not change my level of respect for their knowledge and/or work either, but I think it reflects poorly on their stature, especially as objective researchers. It will also make me skeptical of any future position they present to the public."
Bingo, Cov, another one hit outta the park. Sums up my feelings pretty nicely.

[Covelo]

To play devil's advocate...
If the striped bass is indeed the dominant predator on other fishes (the reason for a control program), then their decrease should have the most impact on species that are most frequently consumed. The ‘release’ from predation by striped bass is highly likely to benefit many other alien fish that are also known predators and competitors on endangered fishes.

Based on numbers alone, of course this is very likely.
Seems plausible but this is in direct contradiction to the authors' first stated assumption that has to be true for the impacts of stripers to benefit native fishes, which was "1. Striped bass predation regulates populations of salmon, steelhead, and smelt, with other predators (other fish, birds, marine mammals, etc.) playing a minor role." They cannot have it both ways and just because stripers may eat a lot more silversides or other non-native fish than native fish, it does not mean they are regulating any of their populations either. This also shows the contradiciton that is present in the authors' own arguments.


Scientists are allowed REASONABLE AND EDUCATED speculation aren't they?

You ever take a statistics or cladistics course?

Is that science? Stats is about as scientific as it gets being that it is basically math. Misapplied frequently though, and usually to meet an intended bias. Cladistics is a different beast but one that is thoroughly debated in the scientific community and constantly evolving. :) I do agree that scientists can make educated and reasonable speculations but those are typically presented differently than what the authors did here in that they are not predictive. They stepped way past reasonable when they stated that it was quite likely that reducing striper numbers would have a greater negative impact on native fish. Further, the authors attempted to limit the scope of the conversation. They named 4 assumptions up front to frame the discussion in a manner that followed their bias. Why only four assumptions? I can think of several other ways stripers could have direct impacts on native fishes -- eg spatial competition. Additionally they slipped in a line that states "If the striped bass is indeed the dominant predator on other fishes (the reason for a control program), then their decrease should have the most impact on species that are most frequently consumed." Again direct predation is only one way a non-native species impacts the ecosystem. Beyond that, why use the term "control program" other than to suggest some large and costly government action that would be needed to control stripers (as opposed to the large and costly DFG that regulates stripers). That is not on the agenda. Removing all regulations for managing stripers is what has been presented. Further why does the striper have to be the dominant predator of native fishes to be deemed worthy of enacting said control program? Reducing the numbers of stripers and other non-native fish is not likely to be the silver bullet, and it should not be played off as being necessary for there to be any action taken. Here again the authors were attempting to limit the scope of the debate.

[matt johnson]

Thanks Bob.

Over the last two years I have been involved with an acoustic tagging study on an Upper Sacramento Basin tributary where outmigrating wild stleehead smolts and a few 120+mm wild Chinook juveniles were tagged. Survival from the tag site to the Golden Gate was better on a wet year (09/10 vs 08/09) and survival was better for fish that stayed in the Sacramento Rivers vs the two pathways through the North delta and the three pathways through the interior delta (Georgiana Slough was a real dead end...). This leads me to believe that juvenile survival through the delta has more to do with how much water is available for fish and how that available water influences chosen routes through the delta. In addition, that available water and influence on pathway is likely directly related to exposure to predation?

I am kind of out of the loop with the other acoustic tagging studies in the delta you may be familiar with, but my understanding is that many of the studies have used hatchery steelhead and Chinook juveniles? Please correct me if I am wrong on this.

I see hatchery and wild salmonids as different species altogether, and I am uncomfortable with how data on hatchery acoustic tagged fish may be being used. If a study is only using hatchery fish, then the reults should only apply to hatchery fish. A Coleman late-fall "meat missle" thats been living in a raceway for nearly a year is hardly a legitimate surrogate for the perfection of nature embodied by a wild salmonid, and is likely going to react very differently or unusually when exposed to challenges in the wild. Matt

[Bob Laskodi]

Indeed, survival is directly related to stream flows, and water agencies are now experimenting with short duration minor magnitude peak flow regimens to help downstream survival rates. Will it work? Who knows. And the term dead end slough indeed has a real double meaning in that they can be death traps for outmigrating smolts. All of the active tagging studies I'm aware of do use hatchery salmon and steelhead smolts (not including stream resident trout which is a separate study). However, one of the reasons I pointed out the release protocols for tagged fish is to illustrate that the predation problem is not just something that happens during mass releases, which is pretty obvious, but also happens to well thought out release strategies designed to minimize predation. And yes, while hatchery fish are certainly stupid at avoiding predators versus their wild cousins, a striper is a predator that will eat anything that it comes across, and it is not wise to assume that wild smolts will not have some predation issues. Tagging studies are still underway, and a few weeks ago another batch of tagged smolts were released to hopefully find their way to the sea!