#silver carp

These guys are becoming a real problem in North America rn. If a water touches the Mississippi River, you’ll find these suckers in there.

You get a Silver Carp

Asian Carp: to eat, or not to eat?

As a means of water quality improvement, silver carp and bighead were introduced into American fisheries in 1973 in an effort to control zooplankton and phytoplankton populations. However, they were much more successful than expected and spread rapidly through the waterways. Because of their plankton-based diet, the carp compete for resources with the native plankton-eaters, such as mollusks and native juvenile fish. Silver carp are notorious for jumping out of the water due to their sensitivity to sound. Aside from potential danger to boaters and fisherman, they make for an easy fishing trip. To quote Landers, "This was the easiest fish I ever caught in my life, but it wasn’t exceptional. A dozen more voluntarily followed it into the boat without any encouragement..." (http://slate.me/1GwyS2z).

The silver carp has an undeserved reputation for being unpalatable. Its cousin, the common carp, is known throughout North America as fairly inedible due to its bony flesh and bottom-feeding diet. However, unlike the common carp, the silver carp feeds on plankton. This results in flesh that is low in fat and low in mercury. The firm, white flesh is described by many to be comparable in taste to Atlantic cod or tilapia. To encourage consumption of the silver carp, industries have renamed it "silverfin" or "Kentucky tuna." The average fish is 13-30lbs, but can exceed 50lbs. It is easy to catch, abundant, large-bodied, and good to eat, making it an excellent game fish.

The harvest of silver carp would allow for an increase in the economy, a decrease in silver carp population, and hopefully an increase in native fish populations. Next time you go fishing, or even just grocery shopping, give the silverfin a try, you'll be surprised.

Jumping silver carp: https://www.youtube.com/watch?v=qfG4vsJ5_xI Asian carp identification: http://bit.ly/182DOxd Distribution map: http://bit.ly/18tPbOM More information & FAQ: http://www.freep.com/article/20110720/NEWS06/110720021

If invasive carp reach Lake Michigan, a buffet of mussel poop and other junk food could help the fish survive and spread.

Once thought to be a food desert for these fish, the lake may provide enough nutrition for two Asian carp species, bighead (Hypophthalmichthys nobilis) and silver carp  (H. molitrix), thanks to their not-so-picky eating habits, researchers report August 12 in Freshwater Biology. That’s bad news because the carp, which have spread to the Illinois River since their introduction to the United States in the 1970s, are just a human-made waterway away from getting into Lake Michigan.

“We should be doing everything we can to keep bighead and silver carps out of the Great Lakes,” says Sandra Cooke, a freshwater ecologist at High Point University in North Carolina who was not involved with the work. If carp gain a finhold, their populations could eventually take off, with difficult-to-predict consequences for the lake’s ecosystem. It’s a familiar trajectory for invasive species (SN: 3/18/17, p. 30). “Time and again, what we actually observe is worse than what we predicted in the first place,” she says.

Earlier studies, including by Cooke, suggested that these fish could survive in some nearshore spots, based on levels of carp’s preferred food, microscopic algae known as phytoplankton, in the top meter of water. But when better options aren’t available, carp will eat detritus, including fish poop or decomposing dead organisms, says Peter Alsip, a freshwater ecologist at the Cooperative Institute for Great Lakes Research at the University of Michigan in Ann Arbor. In fact, he says, the scrappy fish can subsist entirely on the low-quality food that comes from mussels’ fecal pellets and regurgitated particles.

In the new study, Alsip and his colleagues used water temperature, depth, available nutrition, the fishes’ appetite — including for junk food — and their energy needs to simulate where in the lake the carp could reside. Invasive zebra and quagga mussels cover much of the lake floor, presumably creating a “huge portion” of the detritus in the lake. So carp may be able to survive in much more of the lake than previously thought, Alsip says.

JUNK FOOD Fueled by bits of matter from mussel poop, bighead carp (Hypophthalmichthys nobilis) could find enough to eat offshore in Lake Michigan, creating a highway of sorts to nutrition hot spots that would be better for spawning. CREDIT: ELIZABETH SELLERS/FLICKR (CC BY-NC-SA 2.0)

For instance, if bighead carp consume mussel poop and zooplankton in addition to phytoplankton, the surface area corresponding to where the fish could live quadruples on average during the warmest months of the year. Simulations show that the habitable area grows from 11,144 square kilometers to 43,308 square kilometers — about three-quarters of the entire lake. The habitable area for silver carp could double from 1,436 square kilometers to 2,758 square kilometers, the analysis found.

Rather than taking up residence in the middle of the lake, the carp may be more likely to treat the widespread detritus as sustenance to cross the massive lake to areas with better food. It would be as if “these fish want to drive on the interstate and they’re looking for a Cracker Barrel or some other food,” says Jim Garvey, an aquatic ecologist at Southern Illinois University in Carbondale, who was not involved with the study.

Bighead and silver carp were brought to the United States in the 1970s to control the growth of algae, which flourished on pollution dumped into streams. But during floods, the fish escaped their holding ponds. By the 1980s, it was clear the carp were spawning in the wild. The invasive fish are now found throughout the Mississippi River Basin, including on the Great Lakes’ doorstep. In the Illinois River, carp now account for nearly two-thirds of the fish biomass, research by Garvey and others has found.

Silver carp (via USFWS Mountain-Prairie)

Silver carp (Hypophthalmichthys molitrix). Photographed at Gavins Point National Fish Hatchery.

“You can’t catch filter feeders on hook and line”