Carp are widely blamed for the decline in the quality of local fisheries and waters

Here copy of my article over on FishExplorer.COM which talks about the subject that carp are indeed the victim, not the villain in our waters!

Carp, the Victim of the Villain ?

Common Carp (Cyprinus carpio) are an “introduced” species

In the late 1800s there was critical decline in the stocks of lake and river fishes due to an ever expanding population. To answer this concern the U.S. Congress authorized President Ulysses S. Grant to appoint the US Fish Commission in 1871 to oversee the nation’s fisheries interests. Among the first tasks was to consider what species to introduce to bolster the nations supply of food fishes. By 1874 the commission, after long study, issued a report entitled “Fishes Especially worthy of Cultivation”. This report went on to say that no other species except the carp, promises so great a return in limited waters. During the years 1879-1896 the US Fish Commission distributed 2.4 million carp, some of which were sent to Canada, Costa Rica, Ecuador and Mexico.

So, when you wonder why there are carp in our local waters here in Colorado we have the answer. We brought them here as food. The same could also be said of Rainbow Trout, introduced in the 1880s, the Brown trout from the 1890’s. Black & White Crappie 1882, Large Mouth Bass 1878. As fishing as a recreational sport became more popular other “sports fish” species were also introduced, Walleye in 1949, Small Mouth Bass 1951, Wiper, Saugeye and Tiger Muskie in the 1980s – the later being actually introduced to help control sucker and carp populations. I am sure the list goes on. It could be argued, minus the few native species that survive in our waters today, e.g. cut throat trout, channel catfish, etc, the carp were actually here before all of your favorite “sports fish” of today.

Carp are not the problem, they are the Symptom of declining water conditions and environment

Carp are widely blamed for the decline in the quality of local fisheries and waters. It is a fact that, for some of our local fisheries, populations have increased dramatically and the more “desirable” sports fish have declined. The waters have become turbid, muddy and cloudy. This is the general statement I see everywhere and anywhere when they are mentioned. There are hundreds, if not thousands of studies and reports by biologists, wildlife commissions and experts that cite the humble carp as either the “evil one” or a contributing factor.

What is often omitted is that they have been in these waters for decades and only recently has their population growth become an issue. What we need to do is take a step back and look at “what has changed in the environment?”. Carp are opportunistic and will take advantage of a declining eco system. As the biomass declines of other species then the carp can quickly move in to fill the void. They are a very hardy fish, will tolerate poor water, rapidly changing conditions and their reproductive capabilities are staggering when unchecked.

When we look at “what has changed?” we should take into account many factors, which include: increased human recreational use, powered boating, bank erosion, destruction of shoreline habitat and natural plant and weed beds. Increased recreational use and fishing, over-harvesting and removal of predator species, pollution from nearby sources, farm run off and industry, construction of habitation, car parks, decline in nearby waterways, watersheds and wetlands that once provided filtration of water incoming into the lake, reservoir, river. water draw downs, droughts, changes in climate, all also should be considered as factors in why the water has declined in quality for sports fish.

Healthy Habitat

There is no reason why in a healthy habitat, with adequate predation and good water conditions, they cannot live in harmony with other species. Many European trophy carp waters are not only crystal clear but also host many other trophy specimens, especially pike, perch and catfish. The flip side being many of these waters are now managed by syndicates with large influxes of cash to assist with the fisheries upkeep. Careful balance is maintained between predator and prey. Pristine habitat is maintained and the whole ecosystem is healthy. It would be worth noting that some of the fisheries management technique does include netting and removal of large numbers of juvenile carp (and other species) fish to allow adults to grow to truly impressive and immense trophy sizes!

Those huge trophy carp breed like rabbits!

Males are fertile at around 3-4 years of age. Females between 4-5 years. A healthy female carp could easily lay 300,000 eggs during the spawn. Some years there will be multiple spawns. Large reproductive females could produce in excess of 1 million eggs a year. The average carp, in US waters, lives between 14-20 years – depending upon water conditions and available food. Some carp can live in excess of 40+ years though I would doubt in our climate that is likely. As a generalization carp between 7-10 pounds in weight are the most reproductive. As the fish gets older, given the energy and taxation that spawning takes, it breeds less and becomes less fertile. It is unlikely, though I am sure there are some exceptions, that carp over 12 years old are that much interested in breeding.

Sound familiar, we don’t see grandmothers spawning yet more children in our society. Of course, there are news worthy occurrences. The average length for a carp is 24-30” as an adult. Carp can easily reach 2 lbs in weight in their first year and then can grow 1.5-4lb each year thereafter. Growth slows around 12-14 years length increase typically will cease around 15-20 years. So, next time you catch that 34” trophy, 20+ lb monster fish just stop to think, that fish is likely 8-12+ years old and already coming up to, or past, it’s breeding days. Why not return granny to the water to live out the rest of her years in peace ?

Population Control Methods

Many countries, over many decades, have worked to eradicate or control carp in waters where they have become either dominant or undesirable. Techniques involved range from the use of chemical compounds (retenone). Commercial harvest, angler and hunter efforts, cages, barriers, netting, electrofishing, habitat modification. Finally, in likely a dramatic and spectacular display of carp destruction, dynamite and other explosives. Other methods being studied include biological controls, “Judas/tagging males to locate pockets of fish”, “infertile female”, study of the koi herpes virus and so on. All methods can be effective at reducing a carp population. However, long term, what needs to be addressed is what led to the decline in the eco system that allowed the water conditions to decline and the carp to become dominant. Otherwise, the carp will be back, often within a few seasons and in large numbers.

Once the eco system has been restored then harvest of juvenile carp could be performed to reduce the numbers, biological controls implemented to reduce the spawn and remove the eggs before they hatch, predators introduced, pike, flathead and channel catfish, and all your sports fish favorites. These predators need to be protected, in sufficient numbers to keep the populations in control. Slot limits should be enforced and C&R highly recommended.

So, are the carp the victim or the villain ?

Tight Lines as always,
John