Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Ask Not What Your Trammel Nets Can Do For You... Ask What You Can Do For Your Trammel Nets!
Midwest Region, January 18, 2008
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Trammel nets are one facet of our suite of sampling gears at the Columbia, Missouri, National Fish and Wildlife Conservation Office.  We have nets in 50’, 125’ and 200’ lengths, each serving a unique purpose. 


The 125’ nets have the most hazardous job of the trio.  They are used to sample bottom-dwelling fish in the Missouri River.  One end of a trammel is tied to the boat and the other to a buoy.  It is then stretched out perpendicular to the flow of water.  The net is carried downstream by the current, dragging on the bottom.  Many of our species of interest are captured in this manner including the endangered pallid sturgeon.


So why is this hazardous?  The Missouri River is one of the world’s largest and carries a lot of debris.  This includes everything from leaves to large household appliances.  High water events routinely uproot and otherwise pick up large trees to be carried downstream.  Saturated with water, these trees can become lodged on the river bottom. 


When a trammel net, drifting along, encounters one of these, it oftentimes ends badly.  A big, gnarly root wad can ensnare a trammel net better than anything else.  Various strategies are employed to try and untangle the net but it ultimately leads to one thing.  One of our large, powerful john boats will have to pull on the net.  Maybe it comes unstuck easily, maybe not.  In as few as one or two drifts, the 125’ net can become a 67’ net.  Or maybe it turns into a 125’ net sporting a 50’ hole.  Any way it happens, it becomes unsuitable for benthic fish sampling.


Mending trammel nets is one of the more popular winter boat barn activities.  These nets feature three layers of mesh instead of just one like our gill nets.  An eight foot tall wall of one inch mesh is sandwiched between two six foot walls of eight inch mesh.  This combination entangles fish (especially bony species) in any number of ‘bags’ along the net.  The smaller mesh is pushed through one of the larger squares, surrounding the fish.  Though trammel nets are a very useful gear for catching fish, the design of the net demands more tedious mending.  Trammel net repair requires more man hours per net than gill nets by far.


This winter, many trammel nets are being sacrificed for the greater good.  Where two or three damaged trammels may have once lain in their bags, one good net now resides.  Instead of replacing all three layers of mesh along a 10 to 75’ hole, we cut out the bad and tie in the new.  The float (top) and lead (bottom) lines are joined with their counterparts and the layers of mesh seamed to form three viable layers.  We add nets together until our 125’ length is achieved.  Each net in our to-be-repaired pile will become one part of a new net.  From two up to four or more nets can be incorporated into one.


As long as trammels are being drifted on the Big Muddy there will be mending taking place.  Especially when it’s bitterly cold, Columbia NFWCO staff and volunteers can be found in the boat barn, doing the behind-the-scenes portion of trammel netting. 

Contact Info: Brett Witte, 573-234-2132 ex.103, brett_witte@fws.gov
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