What are Silver and Bighead Carp (Asian carp)
Silver and bighead carp are members of the Asian carp family and for the purpose of this article will be lumped together and referred to as Asian carp. As their name suggests, Asian carp are originally from Asia ranging from southeastern China up into eastern Russia. Asian carp are large fish capable of weighing over fifty pounds and measuring over three feet in length. Both carp are filter feeders meaning they get their food as water passes through their gills and which takes out plankton. Inside the gills, the gill rakers of the silver carp are fused, having a sponge-looking appearance. The gill rakers of the bighead carp are not fused. Young Asian carp typically feed on zooplankton, small crustaceans and animals that feed on other plankton. The adult carp typically feed on phytoplankton, algae. For this reason Asian carp are introduced into water bodies to help control alga blooms. In the early 1970’s the carp were brought to the United States and introduced into fish ponds and sewage ponds in an attempt to improve water quality. This action produced mixed results. By the early 1980’s Asian carp escaped and became established in the Mississippi River system.
Before someone becomes very familiar with the two carp they can be difficult to distinguish. One of the easier ways to tell them apart is that on the bighead carp the pectoral fin reaches the start of the pelvic fin. On the silver carp the pectoral fin does not reach the start of the pelvic fin. (Pectoral fins are located just after the gills on the bottom half of the fish. Pelvic fins are the middle fin on the bottom half of the fish, directly below the top or dorsal fin.)
Why are Asian Carp Harmful:
Asian carp are harmful in non-native areas for a couple of reasons. First and foremost is related to their feeding habits. Being large fish and filter feeders means they consume a lot of plankton. This plankton is the base food source for many other living things. All young fish, some adult fish, and mussels (clams) depend on plankton to survive. Reducing the amount of plankton means less food for native species. When those species decline it means less food for the other species dependant on them.
Though not an environmental problem, another negative effect of Asian carp is truly a harmful one. Harmful in the literal sense. As Asian carp feed they are typically close to the surface of the water. When frightened, silver carp in particular, will jump completely out of the water. Though this poses great sport for anglers trying to shoot the carp out of the air with bow and arrow, it creates hazardous navigation conditions. Boaters are sometimes injured as they motor though an area occupied by carp. The vibrations of the motor frighten the carp to jumping out of the water which leads to boaters being hit by carp. Ruined equipment and physical harm can be caused in these situations. In recent years, broken arms and noses have become frequent injuries due to these carp. Without a doubt, water skiing, jet skiing, and other water recreation become dangerous events.
How to Control Asian Carp:
As with all invasive species, early detection can help to slow or stop their spread. Knowing where carp are present helps manage where control methods are needed.
Probably one of the most talked about, impressive, and controversial controls for Asian carp is the electric barrier located in the Chicago Sanitary and Ship canal in Chicago IL. The barrier was completed in 2006 to stop Asian carp from entering Lake Michigan. It is feared that if the carp reach Lake Michigan their ability to filter out the base of the food chain (which zebra and quagga mussels are already working on) will cause the collapse of the multi-billion dollar fishing and tourism industry. The continued increase in decline of plankton means declining bait fish populations, which means declining salmon and trout populations which are the foundation of the fisheries and tourism industry. Although the barrier was completed it has not been used to its full potential due to hazard concerns with commercial and recreational boaters.
During the fall of 2009 DNA tests on the water showed the presences of Asian carp above the barrier, closer to Lake Michigan. However, no fish have been observed. Further actions occurred in early December 2009 as several miles of the canal below the barrier were poisoned to allow the barrier to shut down for maintenance. Steps are also being taken to try to secure funding for projects in 2010 including sealing off culverts and building berms to prevent flood waters from the nearby Des Plaines River reaching the canal. The Des Plaines River does not connect with Lake Michigan or the Chicago Sanitary and Ship canal but runs very close to the canal in some areas.
A step anglers can take to prevent the spread of the carp is to not use them as bait and never release unused bait. Young Asian carp look similar to some common bait fish. As with all invasive species it is wise to thoroughly drain all water and clean equipment before leaving a water body. Also, with the intrigue of the bow fishing possibilities these fish offer, anglers are warned not to release fish into different water bodies. Not only illegal, these actions would be environmentally, economically, and physically harmful.
Chris Hamerla is the Aquatic Invasive Species Coordinator of Lumberjack Resource, Conservation, & Development Council serving Lincoln, Langlade, and Forest Counties in northern Wisconsin. As the Aquatic Invasive Species Coordinator, Chris focuses on implementing AIS prevention and control efforts through public awareness and education programs. For more information or have any questions contact Chris at 715-362-3690 e-mail firstname.lastname@example.org
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