Lewis and Clark Lake Walleye, Sauger, and Hybrids

Did you know that the spawning seasons of walleye and sauger naturally overlap and they sometimes spawn together, forming hybrids?  Walleye/sauger hybrids can also spawn.  Of all four Missouri River reservoirs in South Dakota, Lewis and Clark Lake has the highest percentage of walleye/sauger hybrids.  This means many of the fish caught by anglers in Lewis and Clark Lake that look like pure walleye or sauger are in fact hybrids.

Lewis and Clark Lake Walleye/Sauger/Hybrid Regulations (For more information on Missouri River Regulations, see 2009 Fishing Handbook, pages 20-23)

*These regulations apply to waters of the Missouri River from Gavins Point Dam upstream to the SD-Nebraska border to the point where the river becomes entirely in SD.

• 4 fish daily/8 possession: Walleye/Sauger/Hybrid (in any combination)
• Minimum length 15 inches year-round

 

*Note: There is NO one fish over 20 inch regulation on the previously mentioned portion of the Missouri River due to its status as a border water with Nebraska.

Walleye

Walleye abundance is monitored through an annual September gill net survey.  The average number of walleyes per gill nets is compared with the data from previous years to detect changes in abundance.  The overall trend in Lewis and Clark Lake has been a slow increase in abundance over the last 20 years, with the highest abundance occurring in 2008.
     Walleye Relative Abundance 1984 - 2008

 
The young walleye produced during each year are referred to as that year’s year class of fish.  The majority of the population is from the 2003 - 2007 year classes with a few fish from older year classes.  The 2007 and 2005 year classes were especially strong, however, the 2007 year class won’t be large enough to harvest until later in the summer of 2009.

Almost half of the walleyes sampled in 2008
were longer than the 15 inch minimum size limit!

Relative weight is an index used to describe if fish are in good condition.  High values indicate that the fish are plump and healthy, while low numbers can indicate an imbalance between walleye and its prey.  Walleye relative weight values in 2008 were at the high end of the normal range for Lewis and Clark Lake indicating the walleye population was in good condition at the time of sampling. 

 Walleye condition in 2008 was similar to 2007

 

Sauger

Lewis and Clark Lake contains the most abundant sauger population in the state.  The number of sauger caught per gill net in 2008 was above average and the sample had a balanced age distribution, indicating the relative stability of the population.  Sizes of sauger available to anglers for 2009 are excellent, with 40% above the 15 inch minimum.  As with walleye, sauger relative weights are within the standard range of 80 to 90.

 

 

        Sauger Length Frequency in 2008

Points to Ponder

Gizzard shad are a seasonally available prey species.  With South Dakota located on the northern edge of the gizzard shad range, a high number of the juveniles present after the spawn will not survive through the winter.  However, enough adults do survive to produce a year class of gizzard shad the following spring.  This can lead to large quantities of gizzard shad available to predators, such as walleye and sauger, through out the summer and fall months.  Anglers can experience decreased success due to the amount of prey fish available, dependent upon the size of the year class of gizzard shad present.  Late summer and early fall sampling in 2008 revealed abundant gizzard shad throughout much of Lewis and Clark Lake.  Even with good numbers of harvestable sized predator species such as walleye, sauger and channel catfish present, angling success may have been affected by the abundant numbers of gizzard shad.