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Devils advocate


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#21 Guest_Newt_*

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Posted 05 March 2008 - 05:44 PM

The northeast had great salmon and trout sportfishing before their streams were wrecked; the money spent on stocking bass and 'improving' habitat for them could just as easily have been spent on restoring the native sport fish habitat. Gambusia do a terrible job of malaria control (they don't actually target mosquito larvae), and a great job of damaging local fish and amphibian populations. Can tilapia actually relieve famine? Where will tilapia grow that similar native fish do not exist already?

I understand what you're getting at, but it's a hard point to argue that introductions can be helpful when so few of them actually have been helpful. The best you can come up with is probably "It's done little harm, as far as anyone can tell". Just look at all the money being spent now to eliminate goats on the Galapagos, hogs in Hawaii, pythons in the Everglades, loosestrife in the northeast, kudzu in the southeast, cheapgrass in the west, gray squirrels in Europe, and so on and so on. The point is, they all seemed like good ideas at the time. So as a practical matter, it's probably best to assume that introductions are bad unless proven otherwise.

#22 Guest_mikez_*

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Posted 05 March 2008 - 06:42 PM

The northeast had great salmon and trout sportfishing before their streams were wrecked; the money spent on stocking bass and 'improving' habitat for them could just as easily have been spent on restoring the native sport fish habitat. Gambusia do a terrible job of malaria control (they don't actually target mosquito larvae), and a great job of damaging local fish and amphibian populations. Can tilapia actually relieve famine? Where will tilapia grow that similar native fish do not exist already?

I understand what you're getting at, but it's a hard point to argue that introductions can be helpful when so few of them actually have been helpful. The best you can come up with is probably "It's done little harm, as far as anyone can tell". Just look at all the money being spent now to eliminate goats on the Galapagos, hogs in Hawaii, pythons in the Everglades, loosestrife in the northeast, kudzu in the southeast, cheapgrass in the west, gray squirrels in Europe, and so on and so on. The point is, they all seemed like good ideas at the time. So as a practical matter, it's probably best to assume that introductions are bad unless proven otherwise.


I've taken the Devil's advocate position about as far as I'm willing to go. Truthfully I know nothing of the success or failure of gambusia or tilapia. I threw those out there for the sake of argument because I knew in advance where everybody else would stand. It's no fun preaching to the choir.
Still there are a couple of things that I DO know about. Sportfishing in the northeast is one. There are VERY few people suggesting we eradicate largemouth or smallmouth bass or brown and rainbow trout. If we did, there'd be a rebellion! There are hundreds of towns and thousands of businesses that depend on the revenue those species support. Most of them would not benifit even if brook trout or atlantic salmon populations were intact. There never was and never will be a fallfish, chain pickeral, yellow perch and brown bullhead economy. Those are the natives we'd be faced with targeting in an intact southern New England ecosystem.
From that point of view, I would not agree that "...it's a hard point to argue that introductions can be helpful when so few of them actually have been helpful."

As far as investing money in restoring our native fish runs, well, I suggest you research the state and federal efforts to restore atlantic salmon to the Connecticut and Merrimack rivers. Skip down to the bottom line. The untold millions of dollars of tax payers' money that was and is being flushed down that bottomless pit will boggle the mind. Sadly, people in the know admit, it just ain't gonna happen.

#23 Guest_Newt_*

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Posted 05 March 2008 - 06:52 PM

As far as investing money in restoring our native fish runs, well, I suggest you research the state and federal efforts to restore atlantic salmon to the Connecticut and Merrimack rivers. Skip down to the bottom line. The untold millions of dollars of tax payers' money that was and is being flushed down that bottomless pit will boggle the mind. Sadly, people in the know admit, it just ain't gonna happen.


Sport fisheries are a different kind of thing than other introductions, though, simply because they are not self-sustaining. If the gummint quit putting more browns, rainbows, largemouth, etc. in these rivers, the populations would probably slack off or vanish altogether pretty quickly. They're closer to crops than weeds. I don't know much about the northeastern salmon restoration efforts; if they are a lost cause as you suggest, than that's a damn shame. But that's more an impetus to try to protect the places where the fish are now than an open invitation to introduce exotics.

I think it's a good thing to challenge your own and other's convictions now and again, and I'm glad you did it. But I stand by my position: introductions will likely have negative ecological impacts 99 times out of 100. And they will likely have negligible or negative economic impacts more often than not, once you take ALL the costs into consideration.

#24 Guest_ashtonmj_*

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Posted 05 March 2008 - 06:54 PM

No yellow perch fishery in the northeast/atlantic? I suggest you read some recent transcripts from Maryland DNR public meetings. Yellow perch goes for 10+ bucks a pound in the midwest and the only reason it is commercially fished (and yes they are a minor component of NE fisheries/assemblages) in Maryland is to feed bellies of native midwesterners like myself.

You can restore fish populations and modify fisheries management all you want, as you note, but it doesn't get at the root of the problem; the waterways and habitat can't support the fish. Complain all you want, but direct it at the right people to change how your/our money is spent on fixing the problem not treating the manifestation.

#25 Guest_mikez_*

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Posted 05 March 2008 - 07:18 PM

No yellow perch fishery in the northeast/atlantic? I suggest you read some recent transcripts from Maryland DNR public meetings. Yellow perch goes for 10+ bucks a pound in the midwest and the only reason it is commercially fished (and yes they are a minor component of NE fisheries/assemblages) in Maryland is to feed bellies of native midwesterners like myself.


Ten bucks a pound?? Whoa! I guess when you're that far from the ocean, you eat what you can get.
Ok, ok, perch do support fisheries in some places. I don't believe economically they could ever equal that of the recreational fishery for largemouth bass or stocked trout.

Newt, largemouth and smallmouth bass are totally self sustaining here. I don't think many, if any, northeastern states have a stocking program for them anymore. Smallmouth maybe, not largemouth.

#26 Guest_fundulus_*

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Posted 05 March 2008 - 09:43 PM

Mike may well be right. In the northeast, the river systems are still badly degraded, and to make matters worse we've introduced weedy predators like largemouth bass. Even as Atlantic salmon are repeatedly reintroduced, now they face both a degraded environment and new predators, including exotic salmon species. Blah. It just leaves me with dark thoughts of how gullilble people can be, enjoying largemouth bass and brown trout fishing. And yeah, I'm no fun and all that.

#27 Guest_mikez_*

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Posted 06 March 2008 - 09:05 AM

Mike may well be right. In the northeast, the river systems are still badly degraded, and to make matters worse we've introduced weedy predators like largemouth bass. Even as Atlantic salmon are repeatedly reintroduced, now they face both a degraded environment and new predators, including exotic salmon species. Blah. It just leaves me with dark thoughts of how gullilble people can be, enjoying largemouth bass and brown trout fishing. And yeah, I'm no fun and all that.


Don't forget dams - possibly the worst of the problems and one of the toughest to mitigate. The old fish ladders are inefficient at best, some are useless. The few atlantics that succeed in the Connecticut are trapped in CT, Enfield I believe, and trucked all the way to VT! Not a sustainable plan.
Too bad more dams couldn't be bought out and dismantled. The removal of the dam on the Kennebec in Augusta Me.[Edwards?] has had distinct positive results in a few years time. I personally have witnessed the increase in sturgeon to the point where kayaking at night was a little scarier than usual for the fear one of those 300 pound air borne rockets would land on us. :shock:

#28 Guest_ashtonmj_*

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Posted 06 March 2008 - 09:48 AM

Dam right....sorry I had to. It goes well beyond impacts to fish too. But boy could I start playing devils advocate with dams. Some upstream areas are so impaired now that the downstream reaches are functioning as relatively best they can and without those dams I don't know how well those communities would fair in the short and near term. We're stuck with alot of them, fortunately, unfortunately....but alot of them certainly could/should be removed if not for the ecological reasons the safety reasons alone. Dam breaches and failures are increasing in frequency and it will only take one catastrophic event (the recents ones apparently aren't enough but gastly attention seems to be the case now, right?) to get the deserved attention. The current situation, and possibilities, of a breach of Wolf Creek dam on the Cumberland River is a perfect example.

#29 Guest_nativeplanter_*

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Posted 07 March 2008 - 06:44 PM

You'll have to excuse my ignorence, I'm just an uneducated layman and not qualified to expand on such complicated issues.
However, that's never stopped me before so here goes;
Population dynamics is essentially a 200 year old mathmatical formula. Although it useful to government fish and wildlife agencies for producing funding, justifying policy decisions and keeping the media and public quiet, it is not very useful for describing the natural world.
The problem lies in that it is a function of mathmatics. Math does not mesh well with natural systems because math is absolute. Two plus two ALWAYS equals four and no amount of meddling by man or nature can ever change that.
In nature, two plus two only equals four until a prolonged drought wipes out a primary food supply or until humans wipe out a primary preditor or until an introduced invasive species changes the ecological balance or until all of these things plus more happen at the same time.
At the time of the passenger pigeon's demise, the ecosystem of eastern North America was in a state of unprecidented flux.
First the natives had drastically altered the enviroment with agriculture and associated population increase. Following immediately after, Europeans came on the scene with their even more drastic agriculture practices, gigantic population increases, industrialization, unregulated harvest, introduced species and diseases.
So many drastic changes in such a [geologically] short time frame was too much for some species to adapt. As Dave said [taken somewhat out of context], "Impacts may be subtle, but unless these species are being established in a vacuum, they're still going to be present." And we ain't talkin subtle impacts here!
Having said all that, if you were to strike my use of the word "famine" from the account above, it would still be a viable theory and worthy of being given some thought.


I've been meaning to reply to this.
Just because a concept is old, doesn't make it not so. A lot of your argument above is true, but doesn't reflect your first argument (see March 5, 8:45 am) that overpopulation-caused famine was the source of extinction. (Note that this argument was almost entirely about overpopulation and famine, there isn't much more of a hypothesis if you remove it. Changing environments and reduced resources, yes. But not just a population explosion. Think about it this way - if a species is overpopulated and can't get enough resources (like food), some of them will die. When they do, the rest get the resources. When enough die, there are enough resources to go around and the population decline stops. Put simply, if the environment doesn't change, then a rise in population can not cause it's extinction.

(Please note, I recognize that you weren't really stating your argument, but telling us about someone elses. What I'm saying is that their argument is wrong.)

The real issue (as you note above) is the change in the environment, and the cumulative effect of often subtle impacts.

#30 Guest_mikez_*

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Posted 07 March 2008 - 09:36 PM

I've been meaning to reply to this.
Just because a concept is old, doesn't make it not so. A lot of your argument above is true, but doesn't reflect your first argument (see March 5, 8:45 am) that overpopulation-caused famine was the source of extinction. (Note that this argument was almost entirely about overpopulation and famine, there isn't much more of a hypothesis if you remove it. Changing environments and reduced resources, yes. But not just a population explosion. Think about it this way - if a species is overpopulated and can't get enough resources (like food), some of them will die. When they do, the rest get the resources. When enough die, there are enough resources to go around and the population decline stops. Put simply, if the environment doesn't change, then a rise in population can not cause it's extinction.

(Please note, I recognize that you weren't really stating your argument, but telling us about someone elses. What I'm saying is that their argument is wrong.)

The real issue (as you note above) is the change in the environment, and the cumulative effect of often subtle impacts.



I think the problem was that I did a poor job of elucidating someone else's theory while trying to cram it into as few off topic words as possible.
The idea was that a series of stresses were placed on a species all at once in a very short time and they were unable to adapt.
I don't want to make this a prolonged off topic argument, but I think you are over simplifying the concept of population dynamics. Two hundred years ago it made sense on paper but experience in the interim has proven it is much more complicated. If everything proceeds according to the plan as laid out by eons of evolution, it all stays in balance and it works as you describe. Unfortunately eons of evolution simply can not react quickly enough to the mind boggling changes perpetrated in a few hundred years of human technological progress and population explosion.
The theory I was [poorly] attempting to communicate was that due to human influence, the population of pigeons exlpoded at an unnatural rate that rendered your comfy population dynamic formula obsolete. The combination of stresses, including exhaustion of food recources among others, set them up as vulnerable to the final straw of market hunting pressure.

I do believe there are examples in the literature of populations exploding to the point of exhaustion of their food supply. Whitetail deer come to mind. I know there are others. True, they didn't go extinct, but I never said the famine caused the extinction. Several major stresses, especially something of the magnitude of 19th century market hunting, on top of famine could certainly be enough for a species not adaptable to go extict.

#31 Guest_Moontanman_*

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Posted 07 March 2008 - 10:47 PM

The original article that prompted the Science Daily coverage was in Fish and Fisheries. That volume is open access for the moment, so anyone can download the article as a pdf:

http://www.blackwell...com/toc/faf/9/1

I'm not very comfortable in the approach that the author used: a meta-analysis of FishBase and an FAO database (neither of which are particularly thorough for non-taxonomic information), followed by a literature review for impacts -- particularly when they provides neither the exact list of species used nor the list of references used to characterize negative impacts. I sent the author a polite email asking for his data set (which should have been included as an appendix in the paper), and got a response essentially telling me that I should go recompile it on my own... Ahh, the sprit of comraderie among scientists. Anyway, without the list of publications that the author used, there's no way to independently assess whether the author really thoroughly reviewed the literature or if, say, the 52% of species introduced outside of their native range that he reported to have no impacts were in areas where few people are working on fish ecology (most of Asia, much of Africa, etc).

Anyway, you should still read the paper, if only to see what the fuss is about.

In areas where we have data (like western Europe, and North America), the case is clear -- if an introduced fish species becomes established, it's going to have some negative impact on some portion of the native biota, even if the native fauna has already been highly modified or disturbed. Even species that become established but don't seem to be ultra-invasive at the moment (in North America, tubenose gobies and tench come to mind) are still displacing or affecting behavior of native species (not just fishes) or causing shifts in prey abundance or densities just by being there. Impacts may be subtle, but unless these species are being established in a vacuum, they're still going to be present.

Moon, if we were really serious about saving things like Pseudoscaphirhynchus (rather than using captive propagation and translocations as a lame excuse to get some for aquaria), we should be trying to provide alternatives to cotton farming in the Aral Sea basin, incentives to switch, and reducing irrigation withdrawals from the inflowing rivers. Oh wait, that might actually improve the quality of life for folks in the region -- the State Department would never go for that...

cheers,
Dave



Of course you got me on that to a great extent but I really believe that if we are going to establish exotics in our waters we should be looking at species that need help that only a new habitat could help. Of course very few fish will fit these criteria but some might and i don't think it's blasphimy to look into the possiblity.

Edited by Moontanman, 07 March 2008 - 10:48 PM.


#32 Guest_Moontanman_*

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Posted 07 March 2008 - 10:58 PM

Of course you got me on that to a great extent but I really believe that if we are going to establish exotics in our waters we should be looking at species that need help that only a new habitat could help. Of course very few fish will fit these criteria but some might and i don't think it's blasphimy to look into the possiblity.


Oh yeah, as we have discussed the world seems to run on money not saving endangered species. a tiny sturgeon breed for the aquarium trade could generate much money to go towards repair of it's habitat. somehow we are going to have to see how saving endangered species can turn a profit. Odd aquarium fish can make lots of money if it done right! Unfortunately fish like the chinese paddlefish are gone. A unique species that wasn't a filter feeder like our paddlefish but a piscavore and it was reputed to be a very large fish 23' is mentioned in some places. I still think there are blank eco niches in North america that could be filled by carefully chosen exotics but it seems improbable it will ever happen. Believe it or not the chinese alligator wouldn't compete with the american aligator since they live in completly different habitats. wheither or not there is a place for them is for people smarter than me to say. We will continue to introduce fish that are obviosly harmful for reasons that have nothing to do with saving endangered species.

#33 Guest_daveneely_*

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Posted 07 March 2008 - 11:00 PM

Given what we already know about the impacts of introduced species, I think there's a good case for not introducing any new species. If critters have a problem in their native habitat, then we should be addressing those problems there.

Heck, we can't even get most native translocations right (look at how many hatchery raised razorback suckers and humpback chub have been dumped back into the Colorado, with negligible effect). Our focus should be on restoring habitat first; most species will recover on their own, although sensible and directed captive propagation programs can get some rare species through tough times (e.g., Barrens topminnow)...

Our history of stocking efforts has, for the most part, been one of "let's try it and see what happens." We can do better than that, and we owe it to future generations to at least try.

Dave

#34 Guest_Moontanman_*

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Posted 08 March 2008 - 12:06 AM

Our history of stocking efforts has, for the most part, been one of "let's try it and see what happens." We can do better than that, and we owe it to future generations to at least try.

Dave
[/quote]


Exactly what i was getting at. we can do better than we are now doing but the people who have power usually have very little knmowlege about the dangers of introducing exotic fish.



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