Wednesday, April 18, 2012

Apr 17, 2012: Erv's Field Notes Update (#31)

Fishing pier, 3/6/12 (Kevin Kane)

Jeff Kopaska is a fisheries biologist with the Iowa Department of Natural Resources and a member of Friends of AHHP and Ames Anglers. Here are his comments about the common carp in the park. Thanks Jeff.
As the resident fisheries biologist, I would like to chime in on "The common carp causes few or no problems in the main lake but when it invades the shallow wetlands they stir up the bottom sediment and the reduced transparency of the water inhibits plant growth." In the main lake, the common carp cause the same issues in areas where the sediment is more silt or muck, such as the south-west corner. In addition to stirring up the sediment, they also dislodge rooted aquatic vegetation in their feeding efforts. These activities are both detrimental, but are not as damaging as they are in the shallow wetlands. Angler observations last year indicated a substantially smaller amount of rooted vegetation along the perimeter of the lake. This cannot be directly attributed to the carp, but they may have been a cause. If this pattern continues, we may see a reduction in water clarity in the main lake in the future.
Iowa's eutrophic lakes can generally support 600-700 pounds per acre of fish. At times, carp can overwhelm these systems, comprising up to 600 pounds per acre themselves. This is very detrimental to our native fish fauna, particularly buffalo (largemouth and smallmouth), suckers and carpsuckers, but also bluegills, catfish, bass and crappies. Ada Hayden is a marginally eutrophic system, so its biomass is probably less than 600 pounds per acre. Regardless of the total biomass the system can handle, it undoubtedly is healthier with the majority of that in bluegills, bass, catfish, crappies, and suckers instead of carp.
An additional comment from Erv: Anglers can help by not releasing carp that they catch from the lake.

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