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Fish Cribs 101
By Bob Young – OCLRA Director
Attend some northern Wisconsin lake association meetings and you‘ll probably run into this before long: …let‘s put in some fish cribs so we can catch more fish, or …the fishing has really gone downhill, let‘s put in some cribs to boost the fish population.
If it‘s a clear water lake, you may get some folks who object to the prospect of seeing a man-made structure while they‘re out kayaking on a calm evening. But on most lakes there are some who are convinced it will turn the lake around, back to the great fishing spot it was when they fished it as a kid they‘ve already assembled a work crew, lined up materials, and have a funding proposal drafted for the group to vote on.
Row of fish cribs along a shoreline.
But just what is a fish crib, and what can it do for your lake? Before we can answer that question we need to step back a bit and also consider some other types of fish habitat structures, and the role they play in a lake‘s ecosystem.
All the commonly used fish habitat structures fish cribs, tree drops, brush bundles, half-logs, or even Christmas trees, involve replacing woody habitat to lakes that are often wood -starved. Ever visit a small backwoods lake with no development, and paddle around the shoreline? What strikes you immediately is the large number of downed trees, logs and branches you can see in the shallow waters. Larger, usually older logs are lying in deeper water that you can‘t see.
All of that wood provides food and cover for wood consuming organisms and fish of all sizes and species during some stage of their life. It‘s what lakes do – provide food and cover, aka habitat, for their natural residents.
Contrast that with your own lake. Do you see many downed trees, branches and logs lying in the shallow water? If not, it‘s like many other developed lakes here in northern Wisconsin. For a long time now, trees have either been removed from lake shorelines or pulled from shallow waters. They are wood-starved.
Which brings us back to fish cribs and the other man-made habitat structures. Fish cribs at- tract fish, no doubt about it. When the crib locations are well known, they increase fish harvest. Great for the knowledgeable angler, as long as the harvest is sustainable over time. It‘s still being debated by fisheries biologists whether cribs can actually increase overall fish numbers.
Yet many biologists believe that if installed properly, fish cribs can provide some benefit to lakes. First, consider the real need for cribs in your lake — they are best placed in lakes that don‘t have much natural woody habitat or vegetation. On the other end of the spectrum, lakes with an overabundance of vegetation often have a stunted panfish population — in this case adding cribs adds to the problem by providing even more places for overabundant panfish to hide from predators.
Some other guidelines to keep in mind if you‘re planning a crib project:
Plan to eventually install large numbers of cribs to spread out angling pressure. If you don‘t, your fish crib project may actually work against your goal of improving fishing.
Create effective habitat by weaving the maximum amount of brush into each structure.
Follow WDNR guidelines and rules for installing fish cribs found at http://dnr.wi.gov/ waterways/checklists/checklist_fishcrib.pdf. Primary among them is the requirement to use natural materials (wood). No plastic or metal here, except for fasteners.
Now, what about tree drops, brush bundles and half-logs, or even Christmas trees? They are all forms of woody habitat structures, like fish cribs. Brush bundles and Christmas trees are not often used anymore, primarily because they rot away quickly, and they‘re difficult to anchor. When they break loose they can become a boating hazard or general nuisance.
That leaves the gold standards of fish habitat structures, tree drops and half-logs. Half-logs are thick planks supported on each end by a concrete block. Easy to build and relatively easy to place in shallow water, at least compared to a fish crib. And they work. In bass lakes without much natural woody cover, they are heavily used by spawning bass, especially small- mouths. Again, you must follow WDNR regulations, found at http://dnr.wi.gov/waterways/ checklists checklist_halflogs_old.pdf.
Consider tree drops. The term itself, tree drop, is self explanatory. Trees have been dropping naturally into our lakes since the glaciers receded. And until about a hundred years ago, they stayed where they dropped, providing excellent critter habitat. A man-made‖ tree drop is just that you cut or place a tree so that its butt end is on shore, with the rest extending out into the lake. It‘s secured with a cable to keep it in place.
It quickly becomes colonized with invertebrate life, which in turn attracts all sorts of fish and water lov- ing animals. Each year after the ice leaves, you‘ll see a procession of different fish species use the same tree for spawning and cover, but at different intervals. By the time summer gets here, the results of their spawning efforts – lots of little fish – are seeking shelter in the branches. Imagine that, just like Ma Nature, and it was man-made‖. Once again, follow the rules you find at http:// dnr.wi.gov/waterways/checklists/checklist_treedrop.pdf.
One other bit of advice for the habitat minded – before you even start to plan your project, talk with your local fisheries biologist. They can help you decide what, if any, habitat projects are appropriate for your lake, and give advice along the way.