Here is a part of an article on structure.
This study agrees with my findings on Nimrod. Bigger Crappie perfer more open habitat made of natural materials. I don't use Christmas trees and perfer more open trees like Persimmon. My theory on PVC is also the same, fish use it lots of time cause that's all is there. Also I tell folks you can over fish structures, they are just like baiting Deer. You are building killing fields more than helping the resource, especially on lakes with little or no cover.
Structure Shapes And Material
With decades of projects behind him, Houser is convinced that natural material (i.e. wood and rock rubble) is superior to plastic and rubber.
“The greatest benefit of wood over plastic and rubber is the ability to degrade,” he says. “We want to provide positive fish habitat that lasts just long enough, rather than forever.”
His work has demonstrated that during the prespawn and post-spawn period, adult panfish prefer more open cover. On the other hand, juvenile crappie desire something that is very dense and bushy.Houser points to upright Christmas trees as one of the best man-introduced covers for crappie. They start out with bushy cover for juveniles, but as the tree degrades, it leaves a vertical pole structure that adult crappie like. And it does not last forever.
In Oklahoma, Gilliland says his agency has also studied habitat materials. In the 1980s, a staff researcher looked at preferences of bass and crappie to different brush. He found that crappie preferred cedars, while bass preferred oaks. The researcher theorized that spacing between the branches was the key. Crappie like the tighter spaces of the cedar, while bass like the more open architecture of the oak.
In the 1990s, a graduate student working with the ODWC did a thesis on the relative merits of brushpiles made from cedars, oaks and plastic material called Geo-Web. He found that crappie preferred the cedars, while bass liked the oaks, and that both fish preferred wood over plastic structures.
Gilliland stresses that it’s not that plastic structures are ineffective, but they just do not work as well as wood.
“In barren areas of a lake where you do not have any kind of cover, anything you put in will attract fish, and that includes plastic structures like PVC pipe, Geo-Web or even orange snow fence,” he says. “But they will not attract the number of fish that natural brush will.”
Research done in the 1980s found that crappie also preferred vertical structure to horizontal structures. Height off the bottom was more attractive than the area of bottom-hugging coverage.
“Our agency uses the abundant eastern red cedar and sinks hundreds of brushpiles each year as crappie attractors,” explains Gilliland. “They last six to seven years compared to Christmas trees that last about one season.”
