Hey,

What do you guys think of fish that has been introduced to the United States and now have an established presence? Not surprisingly, the Sailfin Molly are also breeding and thriving here in California. They look kinda cool. Definitely different than store-bought Sailfins.

I also found out about the Porthole Livebearer. I like their potbelly appearance. It is not as exaggerated as the deformed Balloon Mollies sold in pet stores. I love the black markings that gives it its name.

There is also the Mosquitofish that thrives in varied environments across the states and elsewhere.

Do you or would you keep them?

Shortfin Molly - http://calfish.ucdav.../?uid=90&ds=241
Sailfin Molly - http://calfish.ucdav.../?uid=85&ds=241
Porthole Livebearer - http://calfish.ucdav.../?uid=66&ds=241
Mosquitofish - http://calfish.ucdav...?uid=109&ds=241

A major principle of NANFA, the host of the Forum, is that introduced species of any kind are almost always extremely destructive and introductions should be avoided and, if need be, minimized in effects. Many states have laws against transporting targeted introduced species, so collecting them is often illegal. Of course you're in California which started with a small native fish fauna, and has been totally hammered by introductions as much of the landscape has been severely altered. In short we saw introductions as a bad problem, and symptomatic of even wider bad problems.

I think it's a philosophical question, not an academic one. I think that we should try to keep non-natives out of our waters, but I also think that the horse is out of the barn, we can't do anything now. We're at a point where all biologists seem to care about is how much money a species brings to an area, I think it's sad.

I don't think you will find any NANFA people very fond of introduced species. I believe that some non-natives should be protected, but only in the case of a non-removable species.

We're at a point where all biologists seem to care about is how much money a species brings to an area, I think it's sad.

??? Where on earth are you getting this feeling from??? Not my experience in the slightest. No need to be sad about biologists.

??? Where on earth are you getting this feeling from??? Not my experience in the slightest. No need to be sad about biologists.

Fair enough, what I should say are legislative biologists, DGIF,VMRC,NOAA,etc. For example, I was at a committee meeting on an invasive species a while back, and all anyone talked about was the monetary value of different fishes, I got up and said "What makes one introduced species morally superior to another? Money? I'm a Capitalist and I believe we can find other resources, not to mention in the big scheme of things, 10, 20, 30 or 40 million dollars is not very much money. I know people that make that much money in a year. If two species are both introduced they are on an equal level, they're equally non-native. I care about they're effect on native species, not on other introduced species." University biologist are certainly not cut from the same cloth.

Edited by pylodictis, 24 June 2011 - 11:25 AM.

I wasn't there, but anyone saying anything vaguely close to that is a charlatan and criminal who should be removed from office. And I know that some state agencies still think it's the schnizzle to stock exotic trout, which is the act of a charlatan and criminal. We still have a long ways to go with crapola like that.

Fair enough, what I should say are legislative biologists, DGIF,VMRC,NOAA,etc. For example, I was at a committee meeting on an invasive species a while back, and all anyone talked about was the monetary value of different fishes, I got up and said "What makes one introduced species morally superior to another? Money? I'm a Capitalist and I believe we can find other resources, not to mention in the big scheme of things, 10, 20, 30 or 40 million dollars is not very much money. I know people that make that much money in a year. If two species are both introduced they are on an equal level, they're equally non-native. I care about they're effect on native species, not on other introduced species." University biologist are certainly not cut from the same cloth.

My thoughts exactly.

I don't think you will find any NANFA people very fond of introduced species.

I am. Of course, I'm not a biologist. I am by training an engineer, and we tend to think about things differently.

I grew up in Cleveland, a city on the shore of Lake Erie, which sometime in the 60's or 70's held the title of the most polluted lake in the entire world. It no longer holds that name, but that's not because the people here did anything major to fix it. Okay, yeah, after the Cuyahoga River caught on fire, we clamped down more control over what got dumped into the river by our then failing steel industry. But one thing that went a long way to cleaning up the lake and that is not acknowledged by the vast majority of biologists is the invasive zebra mussel. By that time, our native clams and mussels couldn't handle the level of pollution in the water and their populations had severely died off. This was bad news for the whole ecosystem, because filter feeders are necessary for removing a lot of the chemicals and heavy metals from the water column. By coming and living here and filling that niche that our native bivalves were no longer capable of filling, the zebra mussels played a major role in cleaning the lake. They incorporated the bad chemicals in their shells and tissues as they grew, removing them from the water column. Zebra mussels condensed a lot of the toxins into a layer of substrate that was then covered by another layer. Nowadays our water is much cleaner. Every now and then a big storm will kick up one of the deeper layers of soil and the toxin level spikes. *nods* I find it sad that these zebra mussels who played a large role in this recovery are hated by nearly everyone. Fishers and industry hate them for growing on and clogging their boats and pipes, and they get a bad rap. Scraping them off costs a lot of money, this is true. But you have to admit that the water is a lot cleaner (and our native clam, mussel, and snail species are beginning to come back) because of the zebra mussels.

For that reason, I tend to hate on invasive species a bit less than your average person. After all, everything came from somewhere. The idea that our ecosystems are pristine and untainted, going back forever and ever in time without mixing, is just plain wrong. Every creature's range has been continually shifting in subtle ways for many years. The idea of hating on one creature because it's been in this one spot for 10 or 50 or 200 years instead of 700 or 2,000 or 15,000 years is silly. You have to look at the impact of that particular species on the creatures around it in order to judge whether or not it's a nuisance, not the time duration it's spent in that ecosystem. The reason why invasive species can be labeled 'bad' isn't because they're new, but because they sometimes wipe out the previous life in the ecosystem. Like the Nile Perch in Lake Victoria. That was a BAD invasive species, exterminating hundreds of native grazing cichlids and thus causing the eutophication of the lake. But the zebra mussel didn't kill its fellow bivalves and open the niche for itself. It's not like the zebra mussel was like an assassin snail, going in an killing all the other snails. No, it stepped into a niche that had been vacated by a steadily rising toxin level in the lake that had killed off all of the previously existing clams. Its presence was a symptom of human interference. So I like the zebra mussel, and I like how a few years ago we had our first major shell beach from a species of native snail that we hadn't seen much of in decades. They were able to come back because of the water being cleaner now.

This is slightly off topic, but can we stop the myth that Lake Erie is "cleaner" because of zebra mussels right here and right now. I'm tired of seeing it pop up on this forum. It is not. The lake is cleaner because the clean water act, improvments to the treatment of wastewater, and the retrofits to combined sewage overflows. In a simplistic manner, zebra mussels have shifted the pollutants and nothig more. The lake is not turbbid, petroleum products, hydrocarbons, and industrial pollutants are no longer on the surface, but rather in the sediment. Sediment, nutrients, and impervious surfaces are now casusing dead zones and flashy hydrologic regimes. Vast deadzones were not present in the 60's even though the water was by all accounts much more turbid. The lake has experienced a total regime shift in its ecology in just 50 years due to a few invasive organisms. Clearer is not cleaner. Several species of fish are essentially gone and some are actually gone and the benthic biomass is totally different. Native mussels are coming back because of the aforementioned reasons and a literature supported collapse or statsis of zebra and quagga mussels and the refugia of unionids seeding suitable habitat.

*shrugs* It's likely I'm wrong. I admire the zebra mussels for being able to live in such filth, though, regardless of whether or not they helped clean anything.

*shrugs* It's likely I'm wrong. I admire the zebra mussels for being able to live in such filth, though, regardless of whether or not they helped clean anything.

Hell yeah! I admire mosquitofish - they are indestructible, regardless of whether they eat mosquito larvae! If only they had pretty colors like guppies or something. But they don't, so DEATH to them all!

What was it we were talking about?

(Gotta admire those Aliens...they taught the Predators a thing or two...)

Erica I would like to see the studies showing that there were no native bivalves left in Lake Erie before the Zebra mussel invasion. Studies have shown that Zebra mussels pose a danger to natives , this info is from National Atlas. gov, I joined Nanfa and became a member only because I like natives and would prefer them to fish you can buy at any petstore.......so I have trouble understanding the reasoning behind the support of non-native invasives in our ecosystems.

Zebra Mussel Threats







D. Jude, Center for Great Lakes Aquatic Sciences

Threat to Other Species
Zebra mussels are filter feeders. An adult zebra mussel filters up to a quart of water per day, which multiplied by millions of mussels means that the mussels may be filtering all the water in a lake or stream in a day. The animals and algae that are the food of zebra mussels are also the food for larval fish and other native species, so a large zebra mussel population may cause a decline in other animals, including native fish, mollusks, and birds. The filter-feeding activity of zebra mussels causes a related and frequently dramatic increase in water clarity in infested lakes and rivers.

Zebra mussels can severely effect native mussels and clams by interfering with their feeding, growth, movement, respiration, and reproduction. For example, zebra mussels can colonize a clam shell to such an extent that the clam cannot open its shell to eat. Some native mussels have been found with more than 10,000 zebra mussels attached to them. In addition to colonizing native mussels and clams, zebra mussels may attach to slow-moving species such as crayfish and turtles.


GLSGN Exotic Species Graphics Library Water and environmental management agencies are working to protect endangered native species from the threat of zebra mussels. The primary emphasis of this effort is to education so that boaters and fishermen do not inadvertently transfer mussel larvae from one water body to another. In some rivers, boaters are prohibited from traveling upstream from infected areas in an attempt to keep the mussels from spreading.

Edited by wargreen, 01 July 2011 - 09:12 PM.

THANK YOU MATT, very informative post.

This is slightly off topic, but can we stop the myth that Lake Erie is "cleaner" because of zebra mussels right here and right now. I'm tired of seeing it pop up on this forum. It is not. The lake is cleaner because the clean water act, improvments to the treatment of wastewater, and the retrofits to combined sewage overflows. In a simplistic manner, zebra mussels have shifted the pollutants and nothig more. The lake is not turbbid, petroleum products, hydrocarbons, and industrial pollutants are no longer on the surface, but rather in the sediment. Sediment, nutrients, and impervious surfaces are now casusing dead zones and flashy hydrologic regimes. Vast deadzones were not present in the 60's even though the water was by all accounts much more turbid. The lake has experienced a total regime shift in its ecology in just 50 years due to a few invasive organisms. Clearer is not cleaner. Several species of fish are essentially gone and some are actually gone and the benthic biomass is totally different. Native mussels are coming back because of the aforementioned reasons and a literature supported collapse or statsis of zebra and quagga mussels and the refugia of unionids seeding suitable habitat.

See, this is why I wish I could delete some of my posts. You have one little opinion, and people beat you up for it.

Edited by EricaWieser, 01 July 2011 - 09:42 PM.

This is not a direct response to what any one poster has said here. Some folks seem to conflate two different topics: how they feel about a particular species, and how they feel about it being where it doesn't belong. Bullfrogs, mosquitofish, red-eared sliders, red swamp crayfish, green sunfish, and so on are awesome, and I love seeing them here in their native range- but I hate that they have been introduced into sensitive and already-beleaguered habitats elsewhere, where they wreak havoc on the natives. Same for introductions in the other direction- starlings, carp, snakeheads, brown trout, zebra mussels, etc. are interesting critters, and it is of course not their fault that they are here, but just the same it is very unfortunate that they are here.

The literature on introduced plants is perhaps more extensive and less politicized than that on animals. Alarmingly large percentages of the known flora of many areas are exotics. Many of these introductions spread little beyond the initial point of introduction, or else take advantage of highly-disturbed habitats where most natives can't compete, and these are fairly easy to deal with. The first can be rooted out, and the second controlled through better land management. But then there's the other category- the plants that spread like wildfire, intrude into pristine habitats, and change the ecology of a community. The kicker is- you never know before introducing it whether a plant will be a slow-spreading persister like daylilies, a fairly harmless ruderal colonizer like henbit or dandelions, a moderately invasive nuisance like Paulownia, or a horrific community-strangler like tamarisk or Phragmites. Plants that are seemingly very similar- such as close cousins Egeria and Hydrilla- may behave in very different ways once introduced: Egeria is a widespread but minor pest and Hydrilla is the aquatic equivalent of kudzu. All these considerations could be applied to animals too.

Back to the original question: how do I feel about keeping exotic species? I have ambiguous feelings about that one. I think that captive wildlife, both native and exotic, is an invaluable tool for educating and just generally getting people interested in organisms, and consequently in their conservation. On the other hand, any exotic species is a potential risk. Even if we could eliminate careless keepers and short-sighted managers, there is still a possibility of escape; the recent proliferation of lionfish along the east coast has been blamed on escapes facilitated by Hurricane Andrew, and an earlier hurricane carried nutrias from coastal island farms to the Louisiana mainland. Keeping a species already established in your area seems less risky, but I'm sure it carries dangers too.

See, this is why I wish I could delete some of my posts. You have one little opinion, and people beat you up for it.

I'm sure no one means to be hurtful, Erica. It's just that this is a very sensitive topic for conservation-minded people, and we tend to react strongly to opinions suggesting that introductions are a good thing.

See, this is why I wish I could delete some of my posts. You have one little opinion, and people beat you up for it.

Erica I wasnt trying to beat you up, Im sorry if it was perceived that way; I just didnt agree with your opinion on this matter, and wanted to see the studies supporting your statements on the status of native mussels before and after the introduction of Zebra mussels.....as Newt pointed out I feel very strongly on the subject, but I am in no way trying to hurt your feelings, and I apologize if I did.

Edited by wargreen, 02 July 2011 - 12:38 PM.

I'm sure no one means to be hurtful, Erica. It's just that this is a very sensitive topic for conservation-minded people, and we tend to react strongly to opinions suggesting that introductions are a good thing.

I do not think a clear assessment of specific cases of invasive species is detrimental to conservation efforts and the need to control invasives, or off topic wrt what we think about invasives and why. In some ways I think denying any up side at all is detrimental, as almost anything can have up sides no matter how bad they are on balance. Such denials only give the impression that the point being made about invasives is false, when in fact the point stands. I do not see a line item benefit in the assessment of an invasive as any sort of 'suggestion' of a benefit, any more than a dollar is a benefit when paying 5 dollars for it. This denial only gives certain counter-arguments a false air of validity. Zebra mussels is one of those cases where I see facts being unnecessarily denied to counter lasse fair attitudes about invasives. Introductions are NEVER a good idea.

Zebra mussels do strip alga from the water column, suppressing the entire food web. They smother out natives, directly growing on native mussels. Very little eats Zebra mussels, making them a poor bottom link in a food chain, unlike the alga they eat. Regardless of what we do in terms of runoff pollutants they will not go away, removing the possibility of getting the native ecology back. The interplay between our pollutants and zebra mussels is an even stickier issue, where the pseudo-feces creates dead zones where pollutants are constrained to the sediment. But this would not occur without the pollutants in the first place. The full list of problems is quiet large.

However, statements like: http://fl.biology.us...ussel_faqs.html

Most people assume that this increased visibility in the water must mean the water is "cleaner". Not true. All they have done is filter out all the algae which normally would be food for native microscopic organisms.

Is not true. Yes, there is less alga available to the rest of the food chain, but the water column is in fact cleaned of a large amount of pollutants along with the alga etc. that is consumed. It is NOT just less alga or dissolved solids that makes the water 'appear' cleaner, though it does make the appearance look even cleaner than it is. It is in fact cleaner. The down side is of course the loss of alga in the food chain and the dead zones created by the pollutants contained in the pseudo-feces in the substrate. Yet without the pollutants this would not occur even with zebra mussels. This speaks against the notion that the cleaner water is merely the result of the clean water act, which did help a lot. Yet without these pollutants, such as hydrophobic pollutants, to get entrapped in pseudo-feces in the sediment it would not occur. Hopefully, as the pollutant levels drop and the sediment has time to build up over it this will become less of a problem.

Outright denial that zebra mussels and their cousins actually clean pollutants from the water column is not tenable given the biology of mussels and pseudo-feces. To say they shifted the pollutants is valid, but take away the pollutants and the dead zones go away even with the mussels. What remains will eventually be buried by sedimentation. When mussels filter the water they do not get to choose between alga, bacteria, dissolved solids, oils, and pollutants. They take it all in and trap it in a mucous. The edible parts are then transported to the mouth, while the non-edible parts are ejected uneaten as pseudo-feces. This unequivocally includes actual chemical pollutants that gets bound in this mucous secretion. As much as the clean water act helped, with the total maximum daily load (TMDL) and the legal requirements to consider all sources across the watershed, it would take some convincing to show that this was anywhere near the levels needed to bring the pollutants to the levels now seen with zebra mussels.

Ideally the zebra mussel and cousins would be gone and we actually had the water quality standards to have near pristine water quality. Now we must deal with what we have and still need those same water quality standards regardless. I do not think the clean water act goes nearly far enough, even to account for the water quality the great lakes now has with zebra clams. It is not enough to prevent the dead zone in the gulf either, which cannot be blamed on mussels. We can never have what was back because of those invasives, no matter how much we clean up our act, which is a real shame. Even with the river catching on fire it was not until the invasive took over that restoration became impossible. Now it is time to deal with what we have and make it as healthy an ecosystem as possible under the circumstances. Which is now much more limited by a significant portion of the food chain being cut off at the feet by these mussels. That is a heavy price to pay to have some pollutants cleaned from the water column and stratified in the sediment by such an invasive while our pollutant issues remain every bit as problematic. With or without these mussels we will continue to have ecological problems as long as our pollutant runoff problems are not dealt with. Invasives are not the answer even when they can be assigned some minimal benefit that tends to go well into the negative on balance.

To the OP: I think intentional introductions should be prosecuted.

See, this is why I wish I could delete some of my posts. You have one little opinion, and people beat you up for it.

Nobody's trying to beat you up Erica, everybody just want you and anyone else reading this board to be informed accurately.

Erica, I think you are a bit off when you think of lake Erie as filthy. Erie is not just a pit of horrid toxins. Very few waters in this country qualify as pristine, lake Erie is not one of them, but it is also not the worst body of water on the planet.

Also, you should not be so sensitive. Nobody is beating you up, you can give your opinion, but it would be wise to realize that there are professionals who post here, who really know what they are talking about, not just theorizing, and speculating. They are good to learn from. Just like we have all learned from your elassoma experience.