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Gone fishing with an electric boat

September 29, 2012
By GARRY BRANDENBURG , Times-Republican

FISH MANAGEMENT has its own set of pluses and minuses. One problem is how to know what lies under the water's surface in terms of species diversity, size ranges for each, available foods and habitat and long-term prognosis for fisheries improvement options.

At the Green Castle Recreation Area located one mile south of Ferguson, the 16 acre lake would appear to be somewhat "out of balance" at this time with the high probability of getting way out of balance if a future common carp spawn hits the right conditions for a great production year. It appears the stage is being set by Mother Nature and time against an easy fix for fisheries improvements.

Paul Sleeper is this area's DNR Fisheries Management Supervisor. His crew has a special boat rigged with an electric generator and electrode sticks the hang into the water off the bow of the craft.

Article Photos

DNR fisheries crew members Paul Sleeper and Chris Mack from Solon brought their specially rigged electro-shocking boat to Green Castle Tuesday morning to conduct a fish survey. Marshall County Conservation staffers Marty Malloy and Jeremiah Manken assisted. The purpose of the survey was to obtain representative samples of all sizes of predator and prey fishes within the 16 acre surface area lake. An additional objective was to assist and offer advice to the MCCB for long range fish management strategies. One of the bigger predator fishes found on this trip were several walleye in the 21 inch range.

When technician Chris Mack steps on the circuit pad at his feet, current is sent into the water where fish may be lurking. The shock is mild, and temporary, but does cause the fish to become stunned for a few seconds whereby they float to the surface. Men stationed up front use dip nets to place the finny critters into a holding tank. When the tank is well filled, the crew comes to shore and survey data is recorded.

As for the types of fishes found at Green Castle, all the common ones were there such as largemouth bass, bluegill, green sunfish, red-eared sunfish, channel catfish, brown bullhead, walleye, crappie and common carp. Especially troubling are the carp, a species likely introduced by fishermen who illegally used minnows in this lake in past years. And the minnows were not from a verifiable source to be carp free. So upon dumping the bait fish into the lake, rather than destroying them, the lake got uninvited guests which will cause big and costly renovation related questions to be asked at future MCCB meetings.

Sleeper stressed that the common carp they did catch during this survey represent the tip of the iceberg in terms of what is known to exist in the lake. He also emphasized that in some future year when the weather, time and water conditions are optimum for the carp, they will have a very successful spawn. That will in effect be the last nail in the coffin. Any hopes of obtaining a revitalized fishery without intervention is hopeless. At that point the MCCB will be forced to basically start over. The date for any of these actions is yet to be determined, based on weather, planning and budgeting factors. Doing nothing is not an option.

The bluegill populations is stunted and only a very few of the 6 inch fish were obtained. Bass at this time had a good range of small, medium to large specimens. Brown bullheads and carp keep the water turbidity factors high, which cuts off sunlight needed for aquatic vegetation. This in turn affects zooplankton organisms that are the food sources for bluegill. No food equals stunted and slow growing bluegills.

One of the options will be to start over. More than one Iowa lake has been through this process before. Some year soon it will be Green Castle's turn. Starting over means lowering the lake water level as much as possible via the draw down tube built into the spillway structure. Opening a valve will, over time, draw down the water by about 9.5 to 10 feet. That will effectively decrease the water volume of the impoundment by two-thirds to three-fourths. What water remains will concentrate all remaining fish. Then rotenone (poison) will be applied by DNR personnel to kill all the fish. While the lake is in the drawdown condition, perhaps one or maybe even two years, other shoreline renovations, silt removal or island building could take place. Silt removal is the expensive part. Simultaneous on shore camp ground considerations might also take place with its associated infrastructure of water and electrical services. When all is in order, the drawdown valve is closed and the lake would be allowed to refill. A new compliment of DNR stocked fish in the right proportions would be next on the list, this time without common carp and bullheads in the equation.

Green Castle was acquired in 1977. The dam was renovated to new improved safety standards in 1984. A new properly sized spillway tube and drawdown device were built into the dam at that time. There have been partial drawdowns in the past to allow for some shoreline work, but nothing of what may be needed as future plans for Green Castle are implemented in the years to come. It is a big job that must be addressed in order to maximize the potential for this fine recreation area. And the important thing to note in a situation like this is: There Are No Easy Answers To Complex Questions. Natural resource management of lake environments is a complex set of circumstances.


Iowa's regular archery DEER SEASON begins on Monday. The season runs through Nov. 30. It is closed during the shotgun deer seasons. Archery season reopens on Dec. 17 and goes through Jan. 10, 2013. Approximately 60,000 bow hunters will be out and about to see if they will be in the right place at the right time to take a nice whitetail deer. One food source for deer are the acorns from oak trees. Lots of acorns have fallen already with more to come. According to Tom Litchfield, DNR deer biologist, the overall deer herd is slightly above population objectives in central, south central and southwest Iowa. But he also notes that the trend line from past years indicates the deer harvest numbers and strategies are trending downward. Litchfield urges bow and gun hunters to work with landowners to determine if the deer in a particular region are at desired levels.

A reminder to be especially vigilant to the regulations this year. Specifically, the law requires all deer killed to be reported via the harvest reporting system by midnight of the day after a deer is taken. Accurate reporting by hunters is how they can help biologists and their own future deer hunting. A simple call or computer report keeps one legal ... and the fact that accurate data for all future deer management decisions is available is to biologists. Archers in 2011-12 reported taking 23,650 deer, a four percent increase over 2010-11.


A SPORTING CLAY BIRD SHOOT is coming up fast. The date is Oct. 7 at the Marshall County Izaak Walton League grounds, 2601 Smith Avenue. Individual shooters and team shooters are welcome. What makes this extra special is that 100 percent of the proceeds from range fees will be donated to Iowa River Hospice. Hunters, this is a tax deductible event for you. But it will be a huge benefit to those in need at IRH. Food will be provided on site by Smokin G's. A bake sale will be available. Registration begins at 8 a.m. until 2 p.m. Additional details can be obtained from Ruth Dolash at 641-751-1121. (A rain date, should it be needed, is one week later on Oct. 14).


TROUT at SAND LAKE are coming at 11 a.m. on Oct. 20, a Saturday. About 1,500 to 2,000 eight inch trout will be trucked in by a DNR Fisheries transport truck. The DNR raises these fish specifically for several urban area lakes as a put and take fishery. The water on temperature on Oct. 20 will have cooled sufficiently to afford the trout an easy transition to Sand Lake. By bringing the trout to the public, excitement over fishing is increased. Adults that already have a fishing license that desire to keep any trout they catch will need to have purchased in advance the trout fee license. If a person catches and immediately releases trout back to the water, no trout fee is required. Youth that want to keep trout will need to have a trout fee. For details on the regulations, do feel free to call John Steinbach at 751-5246.


ASK THE GAME WARDEN: Who must one show their hunting/fishing/trapping license to? Answer: (page 13 of the hunting regulations, top right) Upon request, you must show your license, certificate or permit to any peace officer or the owner or person in lawful control of the land or water on which you are hunting, fishing or trapping. You must have your license, certificate or permit in your possession.


"If you think you're having a bad day, try being burned at the stake." -Joan of Arc.


Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at PO Box 96, Albion, IA 50005.



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