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A Quest for Small Fish
Midwest Region, September 30, 2008
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An old Irish saying states, “May the holes in your net be no larger than the fish in it.”  This rings especially true when trying to catch larval sturgeon.  These slivers of fish, less than an inch long, floating about in the vastness of the Missouri River are very much needles in a haystack.  It takes specialized gear to catch these tiny fish.  Traditional fishery gears such as electrofishing, mini-fyke nets and trammel nets do not capture these small sturgeon.  However, stern trawling with a small mesh net has proven quite effective.

 

Over the past six years Columbia National Fish and Wildlife Conservation Office (NFWCO) has been continually improving net design and trawling techniques in order to more effectively sample the unique fish community of the Missouri River.  The end result has been greater efficiency in collecting fish, especially small sturgeon.  The years of trial and error, experimentation, and financial investment have paid off in big ways.  These achievements were highlighted during a four-day period in September in which we collected a remarkable 183 small, likely young-of-year (YOY), sturgeon (Scaphirhynchus species).  To put these numbers in perspective, our four-day total exceeded the annual totals for some entire years. 

 

Closer examination of our big September catch yielded some interesting insights.  The range of sizes of YOY sturgeon collected once again suggested a protracted spawn, with some sturgeon likely spawning well into late August and early September.  The abundance of YOY sturgeon suggested that environmental conditions during 2008 were conducive for successful sturgeon spawning.  Over the course of the four days it became apparent that certain habitat types consistently produced small sturgeon, where other habitats seemed devoid of these fish.    

 

Our ability to consistently catch larval and YOY sturgeon represents a positive step forward in sturgeon research on the Missouri River.  Even though Scaphirhynchus sturgeon are widely researched, the early life histories and spawning characteristics of these fish still remain mysterious to some degree.  This lack of knowledge is in large part due to small sample sizes.  Our greater efficiency in collecting larval and YOY sturgeon will likely lead to better understanding of sturgeon in the Missouri River which will hopefully further the wise management of these unique fish. 

 

Colby Wrasse

Adam McDaniel

Brett Witte 

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



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