Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Trawling in the Abyss
Midwest Region, August 12, 2009
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The buzzing drone of mosquitoes greeted us as we launched into the darkness.  Some said we were crazy to trawl the Missouri River at night.  They were right.  Trawling this swift, snag laden river without the aide of sunlight is not an adventure for the faint of heart.  “All in the name of science”, I remarked as I attempted to cough up another mayfly that had taken residence in my throat.   


The science we were after this night was an answer to a long standing question, “Do young-of-year sturgeon utilize shallow water habitat at night?”  Historically the Missouri River was a wide shallow river with numerous islands, sandbars, and side channels.  Today the river is highly altered and little of the natural shallow water habitat remains.  As part of pallid sturgeon recovery on the Missouri River several projects are underway to rebuild some of this important habitat.  Understanding how sturgeon utilize this habitat is crucial for their successful recovery. 


On this night, the tools we used to sample for young-of-year sturgeon included push trawling and bow trawling.  Push trawling excels at sampling water less than a meter deep while bow trawling is capable of sampling deeper water.  The combination of these two gears allowed us to effectively sample a wide range of depths and habitat types.


Over a four night period we collected 62 young-of-year sturgeon.  These data when combined with last year’s night trawling data and compared against daytime sampling should provide us with a deeper understanding of how these tiny, yet important, fish utilize habitat.  Despite the pesky ubiquitous insects and long, sleep deprived nights, I would say that experimental night trawling was a success and may be employed in the future.  


Contact Info: Colby Wrasse, 573-234-2132 x30, colby_wrasse@fws.gov
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