Counting Fish continued...
Data Mining to Manage a Fishery
In 2001, we found that the bass population in mossy lake consisted of a good
variety of sizes from small to large with 20 percent of the bass over 15 inches in
length. Also in 2001, we collected bluegill at a rate of 250 per hour with few fish
measuring longer than 8 inches.
By 2005, few bass were over 12 inches in length, but we found several large
bluegill between 8 and 10 inches.
What happened during these five years to cause such a change in the fishery?
Large year-classes of bass produced in 2002, 2003 and 2004 caused an increase in
the number of bass in mossy lake. During this same period, the relative weight index
dropped steadily from 1.2 in 2001 to .80 in 2005. They became skinnier. Bass growth
rates also decreased from 13 inches at age 3 in 2001 to 9.5 inches at age 3 in 2005.
This bass population had become overabundant and steadily ate away at the
numbers of bluegill. Meanwhile, the decline in bluegill numbers meant less competition
for food for that species, so
that the remaining bluegill grew
fast and to a large size.
If mossy lake anglers are
content to catch many small
bass, but not many of them
over the legal length of 15
inches for harvest, or if they
don’t mind waiting through
slow action for the chance to
catch large bluegills, we might
not do anything more than
continue to monitor the lake. Angler surveys, however, tell us that there is general
discontent with the fishery and we need to take action to improve it.
In this case, a 12- to 15-inch slot limit on bass and an increase in the daily limit of
bass from two to four or six may be all that is needed. Anglers could take more bass,
but they would not be able to harvest bass between 12 and 15 inches long.
These regulations would improve bluegill production by allowing a bigger bass
harvest, reducing the number of bass and permitting more small bluegill to survive.
The new regulations would also provide a great catch-and-release fishery for
12- to 15-inch bass, many of which would find enough food to grow longer than 15
inches, making them eligible for harvest or catch-and-release trophy fishing.
The changes won’t happen overnight, but these regulations should steadily
improve the fishing in mossy lake.
Catch Rate per Hour in Mossy Lake
| Fish |
2001 |
2003 |
2005 |
| Bass |
80 |
120 |
175 |
| Bluegill |
250 |
135 |
92 |
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Outdoor Recreation
About This Article
Author
GREG STONER has been the Department’s
fisheries management biologist at Lake of the
Ozarks since 1991. He also assists landowners
with pond-related issues throughout Camden,
Miller and Morgan counties. When not at work,
Greg spends as much time as possible fishing in
the Niangua Arm of Lake of the Ozarks with his
wife, Sherri, and his kids, Alex and Katie, who
luckily all like to fish.
Photographers
CLIFF WHITE is a life-long Missouri resident. After nearly 10 years as a staff photographer for the Missouri Department of Conservation, Cliff recently took on management duties as Art Director. Now he supervises on an unruly gang of super-creative folks. In his spare time Cliff likes to play old-time folk and bluegrass music, float fish and chase the occasional turkey.
Department of Conservation photographer NOPPADOL PAOTHONG discovered his love and passion for wildlife photography in college in 1995. Born in Thailand, he came to the United States in 1993 to study graphic art before switching to journalism. He has worked as a full-time photographer at the Joplin Globe and the Springfield News-Leader, and has achieved more than 60 regional and national awards.
Gallery
Click to view gallery.
