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If anyone is from Pennsylvania or New Jersey you're probably aware of how badly we got flooded out along the Delaware River last month. Well, I work for a county that was very badly hit in NJ and during the summer I'm along the river a lot. So earlier this week me and a co-worker were checking a site that's basically a large pond of standing water left over from the flood (now well off the river but during the flood was 20 feet underwater). Generally this spot does have a bit of water in it from rain but is no bigger then maybe 10'x10' and a half a foot deep... well now it's 5 or 6 times that size and maybe 2' deep.

The first time we checked this site on Wednesday as I walked up to it I was startled to see a HUGE fish laying dead on the side of puddle. It had to be nearly 2' long and immediately I knew it was a Carp (Cyprinus carpio). It only took a few more seconds to realize this puddle, which has a decent amount of water but is rapidly drying up, had about another 2 dozen of this MASSIVE Carp swimming in it. It was rather heartbreaking to see some of them gasping at the surface and a few more dead on the bank.

My co-worker is also a fish-enthusiast so we both knew what we had to do... so we donned our hip-length boots, secured some sturdy nets and set about trying to rescue as many of these fish as we could. Let me say: regardless of the lack of oxygen and the fact that this puddle was drying up this was no easy task. These fish are huge and can give an experienced fisherman a difficult time on a fishing line. When all was said and done over the course of two days we managed to save about 15 or so of these fish and countless smaller catfish and minnows. Not all but at least some will get a second chance. The owner of the property was extremely thankful to us because they had to try and drain this puddle down with a pump and hated to do it with all the fish in there.

Today I go to Petco just to see what they have. I knew I needed a few Pristella Tetras because I lost most of my school a few months ago. I asked the associate for three pristella's and showed him exactly what I wanted. He wasn't your average idiot LFS clerk either.. he actually knew his stuff. When I got home I realized I didn't have three pristella's but infact three turquoise australian rainbows. I've always wanted rainbows but these are around $6 or $7 so it was too pricey to make a school of them. I got my three for the price of Pristella's at $1.59 each. Unfortunately it's not a proper school (I like 6 or more) and my pristella's are still in weak numbers but at least I finally got some rainbows at a VERY reasonable price. I can also go back for real Pristella's later.

Sorry for the long post.

I don't intend to criticize your valiant efforts, good on you for taking it upon yourself to safe suffering fish. On the other hand I think it's important to note that carp are an introduced noxious pest in North America, and for the greater benefit of our wetlands, any specimens that are captured should be destroyed. Before you flame, let me explain. I am a fish lover, I don't enjoy killing fish. The problem with carp is that they are extremely destructive. Their plant eating, burrowing, rifling through the mud in our wetlands is destroying natural plant cover that native fishes use for survival as very young babies before they move out into larger, deeper waters. The carp's natural feeding behaviour causes turbidity in the water and makes a mess of the marshes.

"These nuisance species thrive under conditions of low dissolved oxygen and high concentrations of suspended solids. They can also tolerate contaminated sediments and are frequently found in heavily contaminated environments. Their spawning and feeding activities uproot vegetation and stir up bottom sediments. They prey on benthos and juvenile fish, and eliminate desirable fisheries through predation, competition, and habitat destruction."

"They are now the rulers of the waves, eating the plants that once thrived there and keeping the water silty brown so sunlight cannot penetrate to the bottom. Plants cannot grow in such a dark environment. Unfortunately, due to its rapid reproductive ability, its destructive activities and low economic value due to contamination, carp has become an enemy..." [link=http://www.science.mcmaster.ca/Biology/Harbour/CARP/CARP.HTM]http://www.science.mcmaster.ca/Biology/Harbour/CARP/CARP.HTM" style="COLOR: #fee100[/link]

Many other animals rely on our marshes, bogs and other wetlands as their natural habitat including mudskippers, birds, etc. Carp, introduced from Asia, pose a severe threat to many of these species.

It sounds cruel and heartless, but for the sake of our wetlands, it is very important that we each do our part to reduce the carp population in local waters. Any carp that are captured while fishing or during other activities should be destroyed, never released back into the water where they can spawn and continue to wreak havoc.

i agree entirely - kudos for saving the fish, but they really should have been used for fertilizer, nothing else. carp have made a total mess of things here in australia too. indiscriminate feeders, mess machines.

Some intriguing perspectives:

"Columbia FRO biologists are monitoring five Asian carp species in the Lower Missouri River. These are considered Aquatic Nuisance Species. An aquatic nuisance species is a fish, mollusc, or other aquatic organism that is not native to an area and is considered to be a nuisance or threat to native species. The common carp was introduced to the United States in the 1800s and is now considered to be "naturalized". The importations of the other four Asian carp species (grass, bighead, silver, and black) were for use in the aquaculture industry. These carp may be out competing native species for food or habitat resources. We are concerned about the effects that these carp species may be having on native fish and shellfish when released or escaped into the wild. Grass, bighead, and silver carp are found throughout the Mississippi River drainage. Illinois Department of Natural Resources staff reported the first catch of black carp in the wild in March 2003.

The bighead and silver carp grow to large sizes (50-110 lbs.) and quickly become some of the most abundant fish captured from an area. They have become so abundant in the Missouri River commercial fishermen report catching several hundred pounds in a single net. Columbia FRO staff found juvenile bighead carp in the Missouri River at Overton during and after a flood pulse event in 1997. This indicates that river and floodplain conditions are sometimes suitable for these fish to spawn. Columbia FRO hosted an Asian Carp Management and Control Workshop in 2000 and continues to be involved in Control Plan development. For more details, view the Asian_Carp_Workshop_Report. Our biologists are also working jointly with the USGS Columbia Environmental Research Center in their efforts to radiotrack bighead carp."

(Emphasis mine)

From http://www.fws.gov/midwest/columbiafisheries/asian.htm.


"Effects on the Environment

Many Australians see carp as a threat to both native fish species and to river ecosystems. They have been blamed for a decline in native fish populations, blue-green algae blooms, muddying the rivers, damaging stream banks and irrigation drains and for the loss of aquatic and river-side vegetation. They also annoy many anglers.

Scientific evidence is still being assembled, and effects are often difficult to attribute solely to carp. The Lachlan River in western NSW is a good example. Carp first invaded the river in the floods of the 1970s, and now many people blame them for: reduced native fish numbers; high turbidity (muddiness) and collapsing river banks. These events began around the time when carp became common. However, Wyangala Dam, on the upper Lachlan was also upgraded and enlarged in 1969, and the environmental changes can also be attributed to the increased power of Wyangala Dam to alter the river's flow in the 1970s.

The environmental factors interlink in many ways. For instance, aquatic plants may reduce turbidity and conversely, turbidity may restrict plant growth, while blue-green algae and aquatic plants may both compete for nutrients. This complexity makes the impact of carp on the environment difficult to establish precisely.

Turbidity

The most common complaint is that carp significantly increase the turbidity of western rivers. This is claimed to result from the carp's habit of sucking up silt from the bottom and expelling it into the water. Recent research has shown that turbidity does increase in enclosed waters with high densities of carp and low food levels (for example when lakes and billabongs are drying up). At lower densities and with higher food levels, carp do not effect turbidity. In earlier research, the effects of carp were not easily divorced from the effects of wind turbulence or other factors associated with these types of waters. Recently a few more-detailed studies have begun.

Nutrients

Recent emphasis on ways to prevent toxic blue-green algal blooms has focussed attention on carp as a factor. Blue-green algae thrive in nutrient-rich water, and it is claimed that carp contribute dissolved nutrients (nitrogen and phosphorus) in their excreta. But recent experiments found that in the short term, nutrients are actually 'locked-up' in the increasing mass of growing carp.

Where sediments are rich in nutrients, it is possible that the 'mumbling' feeding behaviour of carp could increase nutrient availability in the water by resuspending sediments. However, carp only recycle nutrients already in the aquatic environment.

Any strategy for controlling blue-green algae must be wide-ranging: including the removal of carp, reducing the nutrients entering the environment, and better management of stream flows.

Vegetation

Carp have been accused of destroying aquatic vegetation. These claims were largely based on overseas literature, and until recently there was only circumstantial evidence to support them here. In the 1980s, it was suggested that carp had destroyed pondweed (Potomogeton sp.) and musk grass (Chara sp.) in experimental enclosures. Recently, similar effects were shown under rigorous experimental conditions with ribbonweed (Vallisneria sp.) and musk grass. Again, the maximum damage was observed when many carp were present and little food was available. The plants were not destroyed by grazing, but were uprooted by the carp's feeding behaviour. However, some plants were especially sensitive, for instance ribbonweed was uprooted even when carp were present at a low density (226 kg per ha) and provided with extra food.

Experimental work in irrigation channels also provides some evidence that the feeding activity of carp may prevent the plants re-establishing once they have been destroyed. If so, this may provide a mechanism to explain the permanent removal of water plants from many habitats.

High densities of carp, with a dwindling food supply, can occur in lakes and billabongs as they dry down in summer. Under these conditions, carp may initially uproot and destroy the water plants and then prevent them from re-establishing when the water level rises.

There is a lot of anecdotal evidence that vegetation was destroyed in many lakes, rivers and irrigation channels as carp spread in the 1970s.

Bank Stability

There are many reports that the feeding activity of carp undermines stream banks and makes them collapse, causing increased erosion and siltation, and the death of riverside trees. Bank instability may be caused in many areas by increased flows from river regulation, and the destruction of bank-side vegetation by tree removal, over cultivation and stock access . However, observations made in irrigation districts show that, under certain conditions of soil and vegetation type, carp may actively undermine banks of irrigation drains causing them to slump.

Effects on Native Fish

Carp as predators

There are very few recorded instances of fish remains being found in carp stomachs, or of carp capturing live fish. Consequently, it is unlikely that carp actively prey on other species of fish. Carp have special pharyngeal teeth in their throat. The size and shape of these pharyngeal teeth, and the lack of grasping teeth in the mouth make carp inefficient at handling large, struggling prey such as fish. There have been no reports of predation on young fish or fish eggs, although these would be digested rapidly and thus be difficult to detect in gut analyses.

Competition

Carp can compete for food and spawning sites. In the latter case, since carp spawn at lower temperatures than most native fish, they begin laying eggs before most other species and there is unlikely to be overlap. Places used by carp for laying eggs, such as submerged grass or aquatic vegetation, are not used by large native fish species. However, smaller native species such as gudgeons and rainbow fish do use these areas and may be excluded.

No Australian studies of competition between carp and any native fish species have yet been reported. Neither have any studies adequately investigated whether competition for food influences fish numbers. Theoretically, competition for food can only occur when different species eat the same food and the supply is limited.

Juveniles of all Australian freshwater fish consume plankton. Carp are often found in large numbers in shallow, flooded areas that may act as nursery areas for native fish larvae and juveniles. As carp of all sizes are predators of zooplankton they may be consuming much of the food of young native fish. There may also be some overlap in the diet of carp and adult silver perch, and bony herring. Silver perch eat insects, small invertebrates and some plant matter, and juvenile bony herring eat zooplankton, and graze algae and strain detritus for food as adults. Most adult native fish eat different things to carp. For example, golden perch, Murray cod and freshwater catfish consume small fish, shrimps and yabbies.

Disease

Carp act as carriers of the anchor worm, Lernaea cyprinacea. This parasite was first noticed on native fish immediately after carp first colonised many impoundments and rivers in the Murray-Darling basin. Many native species of fish and trout are highly susceptible to infection. Heavy infestations may prevent spawning and can be fatal for large adult Murray Cod and golden perch larvae.

Other Factors Affecting Native Fish Populations

To put the effects of carp in perspective, it is important to understand some of the factors that influence native fish populations;

Fishing

There has been a huge reduction in native fish numbers since European settlement of western New South Wales, but the decline is difficult to quantify as there was no research in the early days. Despite the recent decline in licensed commercial fishing, the modern trend for owning 4WD vehicles, small boats and outboard motors has meant increased recreational fishing pressure for most inland waterways.

The large Murray cod that were abundant in the heyday of the paddle steamers are now scarce. Successive generations of commercial, recreational and illegal fishermen have removed them. Aggressive and territorial fish like Murray cod and trout cod are extremely vulnerable to fishing pressure and, without doubt, fishing has reduced their abundance and distribution.

River Regulation

As well as fishing there are other direct and serious threats to native fish populations. The ecology of the whole western river system has evolved in response to irregular cycles of drought and flood. Native fish require flooding for successful spawning or recruitment. Interference with the natural flows of these river systems is likely to seriously affect fish populations. River regulation reduces spring flooding and produces higher flows in summer in the southern part of the Murray-Darling Basin. The frequency and extent of floods are now much less because run-off is now stored in dams in the upper catchments.

The ever-increasing demand of irrigators annually diverts between 10, 000 and 11, 000 gigalitres (GL), (1 GL = 1, 000, 000 000 litres) out of the Murray-Darling river system. This figure represents almost twice the average annual flow to South Australia!.

Dams and weirs prevent the upstream migrations of many species, although providing suitable fishways minimises the effects of some low level weirs. Cold, anoxic water (water without oxygen) discharged from the bases of dams has robbed native fish of thousands of kilometres of suitable river habitat. Changes in channel shape caused by removing logs and snags, and siltation due to inappropriate land-uses have also reduced the habitats available for native fish.

Recent research has shown a link between increased river regulation and reduced species diversity. Samples from highly regulated rivers had many more alien fish, like carp and redfin perch, than native species.

Introduced Predators

Introduced predators such as trout, redfin perch and gambusia (mosquito fish) can also reduce native fish numbers. For example, trout are strongly implicated in the major reductions that have occurred in trout cod, Macquarie perch and galaxia populations."

From http://www.irysec.vic.edu.au/sci/introduced/carpfact.html.


[The above statements refer to Carassius carassius.]


"Industry & Ecology
The Exotic Species War
Scientifically mandated or culture clash?

by Ronald Bailey

Driving around in the Patagonian Andes in December, my wife and I were enchanted by the masses of luminous blue lupines and brilliant yellow scotch broom lining many of the roads. We stopped frequently to take photos of the floral abundance. How insensitive of us! Both, it turns out, are evil foreigners. Lupine is from North America and scotch broom hails from Europe.

Since 1992, the nations of the world have been waging a war against such foreign invaders under the Convention on Biological Diversity. In the United States the public regularly reads anguished stories about the "damage" being caused by alien invaders such as zebra mussels and purple loosestrife. Environmentalist groups including the Natural Resources Defense Council, the Union of Concerned Scientists, and the National Wildlife Federation fiercely denounce these foreign intruders, urging Americans to band together to force these invaders from our shores.

In response, Congress passed the National Invasive Species Act and the executive branch has adopted a National Invasive Species Management Plan aimed at closing our borders to alien species. NASA warned recently, "Non-indigenous invasive species may pose the single most formidable threat of natural disaster of the 21st century." But is all this jingoistic furor justified? Some biologists and other analysts are beginning to doubt it.

For example, University of California-Santa Barbara biologist, Daniel Botkin, points out in his article "The Naturalness of Biological Invasions," that "biological invasion is a natural process everywhere, requisite for the persistence of essentially all species on Earth over the long term. Being able to seek new habitats and survive in them is essential in an environment that changes at all scales of space and time."

In the May 2005 cover article for Discover, senior editor Alan Burdick asks the startling question, "Are Invasive Species Really So Bad?" (not yet available online). The article concludes, "Fifty years of invasion biology has failed to identify a clear ecological difference between an ecosystem rich in native species and one chock-full of aliens. Invasions don't weaken ecosystems—they simply transform them into different ecosystems, filled with different organisms of greater and lesser value to us." (To be immodest, this is exactly the point I made in my "Bioinvaders" article nearly 5 years ago.) Introducing new species generally boosts the total number of species dwelling in any given ecosystem.

What about the claim that invasive species pose "the single most formidable threat of natural disaster"? It is certainly the case that some introduced species have detrimental effects. Think West Nile virus and Norway rats. We should take steps to prevent the introduction of disease organisms and parasites that show a high likelihood of harming species that we value.

But even the NRDC admits that over the past two centuries, only one in seven of the thousands of introduced species have caused environmental, health, or economic harm. In fact, most, such as wheat and cows, have provided people with far more benefits than harms. And while some species are threatened with extinction by the introduction of outside species—most infamously the case of the brown tree snakes that killed off several bird species on the isolated island of Guam —in fact, fewer than 6 percent of species considered endangered are menaced by non-native species, according to Burdick.

Ecologists had assumed that introducing alien species would be detrimental because these species would disrupt ecosystems in which species had co-evolved for millions of years. Species from different ecosystems would harm tightly functioning "natural" plant and animal communities. This assumption has recently been called into question by the creation of an "accidental rainforest" on Ascension Island in the middle of the Atlantic Ocean. As New Scientist (subscription required) points out, Ascension's bare central peak once called White Mountain is now covered with an extensive cloud forest consisting in guava, banana and wild ginger, bamboo, the white-flowered Clerodendrum and Madagascan periwinkle, Norfolk Island pine and, eucalyptus from Australia and is renamed Green Mountain. This new rainforest, less than 150 years old, is an affront to conventional ecological wisdom that species must co-evolve in order to function together. Instead the Ascension rainforest supports the dissident notion that species engage in "ecological fitting". That is, species make the best of what they have.

Ascension's rainforest is evidence that nature is super resilient and that moving species around the globe is unlikely to cause wide-scale ecosystem collapses. Ecological puritans loathe the new Ascension Island rainforest as a pastiche and lupine and scotch broom in Patagonia as sinful aberrations. However, less conservative temperaments welcome foreign species as fascinating scientific and aesthetic experiments that can enrich landscapes such as Patagonian roadsides. Ultimately, the battle against exotic species is a cultural and aesthetic war, not one compelled by scientific evidence."

From http://www.abetterearth.org/article.php/1033.html.

Last edited by Veneer at 06-May-2005 22:27

See Carp - Queen of Rivers or Pig With Fins?.

LOL! I never knew any of that. Of course I was aware carp were an introduced species but I had absolutely no idea they were a noxious pest. Infact, I thought they were welcomed especially by sport fisherman because they can really put up a good fight.

trystianity, I wouldn't flame you for your point of view... in fact that's very interesting information. I don't regret saving them, however. Letting a few dozen die a horrible death wouldn't have made a difference in the grand scheme of things anyway, IMHO.

When all is said and done... at least I still got my rainbows. nice and cheap.

EDIT: This will also make for an amusing joke at work on Monday. "Hey, guess what we shouldn't have done???"

Last edited by Rewd at 07-May-2005 14:15

Even though they're nuisances they are some of the best fighting fish for fishing and are great eating.The most fun I've ever had fishing is when I went spearfishing for them and got 3 eight pounder fish.

Everyone I know would have been more than happy to take those carp off your hands. They are highly desired for private large ponds and lakes. Anyone with a good fishing pond has carp. It's hard to think of a body of water without carp in it. This is the first time I've heard anyone with a complaint against them.

hey veneer, thanks for the interesting read. i can only go on my own experience doing work experience with CSIRO and on my own farm, where there could be no doubt of the threat posed to fragile ecosystems which do not normally support fish of the carp's size. the year after my father introduced carp to our dams, there were no more frogs, no more trout (also introduced) and much worse water quality.

"Even though they're nuisances they are some of the best fighting fish for fishing and are great eating."

I always heard they were really nasty to eat.

Oh no they are awesome eating. It depends on where you catch them though. If you get them from a river or large lake then thoss are they best ones. Look for white colored carp their supposedly to be the best eating

When the flood waters used to get out in Tennessee I used to hunt them with my compound bow. I would splash in the water then you would see them coming. Poke.. Reel.. scale.. pressure cook.. mmmmm crackers and hot sauce..

FreeBlaze