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Field Notes No. 03 (July 30, 2011)

From: eklaas@iastate.edu [mailto:eklaas@iastate.edu]
Sent: Saturday, July 30, 2011 4:22 PM
Subject: Field Notes No. 3
Friends of Ada Hayden Heritage Park:

Jeff Kopaska, DNR fisheries biologist, presented an informative program on fish management at Hayden Park on Thursday evening, July 28.

He said that borrow lakes and surface mines (such as Hayden Park lake) are not "natural" elements of the landscape and therefore it is not easy to maintain a quality fishery in such lakes. These lakes tend to have a smaller littoral (shallow shoreline) zone habitat for spawning and nursery areas and tend to be nutrient-poor and less productive.

Monitoring of the existing fish population by the DNR has revealed that largemouth bass, bluegill and yellow perch populations exist in fair numbers with smaller fish present. Black crappie are present in low numbers but are healthy and are good-sized. Channel catfish are present in good numbers and have a good size structure within the population.

The DNR is attempting to enhance the recreational fishing opportunities fo! r anglers. Hybrid striped bass fry were stocked in 2009 and 2011 and stocking will continue in odd years. These fish grow rapidly and feed on an under-utilized existing prey source (gizzard shad) in the lake. Striped bass have exhibited exceptional growth since the initial stocking. This population has the potential to provide a trophy fishery for Hayden Park.

A one-time stocking of fingerling walleye occurred in 2010 when the fish became available from a research project at Iowa State University. The DNR does not ordinarily stock walleye in lakes that are under 500 acres because research has shown they do not do well in small lakes.

Channel catfish will be stocked biennially in even years. Small channel catfish have been observed in the lake, so natural reproduction is probably occurring.

Rainbow trout were stocked in the fall and winter, 2010-11, to provide trout fishing in central Iowa. Rainbow trout is a good species to introduce ki! ds and non-anglers to fishing. It is believed that 80-90 percent of the fish were caught in the first year. Trout require cold water and most may not survive summer heat. Although Hayden Park is deep and cold, a sharp thermocline (a depth at which temperature quickly changes from warm to cold) sets up in the summer that prevents deeper cold layers from mixing with the warm upper layers of the lake. Low oxygen below the thermocline prevents fish from living below the thermocline.

The DNR and their conservation partners promote family fishing events and you can look forward to future events at Hayden Park. Friends of Hayden Park will try to keep you informed when these occur.

The next interpretive program at the park will be Sunday, July 31 when Diane Debinski will lead a field trip to find and identify butterflies. Meet at the shelter at 2 pm.

On August 4, Deb Lewis will lead a field trip to see late summer prairie flowers. Meet at the parking lot off Harrison Road on the south side of the park at 6 pm.
Erv Klaas