DNR News > Recent Releases

Improved Water Clarity and Aquatic Plant Growth at Clear Lake Boost Fingerling Survival
by Lowell Washburn
Posted: September 29, 2009

CLEAR LAKE - The forage is back. Fingerling nurseries are full. Clear Lake fish populations are returning to a healthy balance. That's the assessment of DNR District Fisheries Biologist, Scott Grummer as fisheries crews put a wrap on this year's annual Young of the Year Fish Surveys.

The fish production survey has been conducted at Clear Lake every year since 1972 and is designed to document annual spawning success and young fish survival, says Grummer. Nighttime net crews visit seven standard locations during August and return again in September to collect and inventory fish from a dozen species. Results are used to monitor reproductive success of all species, evaluate the annual success of walleye stockings, and aid in predicting future growth and abundance of sportfish.

"Water temperatures fluctuated wildly during the 2008 spawning season and fish production was poor," said Grummer. "This spring we had more consistent water temps, increased clarity, and excellent growth of aquatic plant life. The result was a phenomenal spawn which resulted in more than a hundred fold increase in fish production over last year.

"Clear Lake's yellow bass population provides a very important forage base for larger predators, like walleyes, and yellow bass are also very popular with anglers," noted Grummer. "Yellow bass enjoyed an extremely successful production effort this spring and those young fish will play an important role in supplying recruitment as aging adults begin to leave the population."

Other survey highlights include banner spawning success for yellow perch, bluegill, spot-tail shiner, and crappie. Production levels for each of those species reached or exceeded the long term [1972 -- 2009] average. Walleye survival increased by 300 percent during 2009 and now hovers slightly below the long term average. No [zero] young of the year black bullheads were observed at any of the survey stations.

"The 2009 survey results are extremely encouraging," says Grummer. "In addition to being observed in large numbers, fingerlings from all fish species are also in excellent body condition --- very robust. Walleyes are currently measuring up to 6 ½ inches in length, which is as good a growth rate as anyone can expect. Perch are measuring three inches, and yellow bass are at 2 ½ inches.

"We also saw a real surge in underwater, aquatic plant life this summer which is very important for providing food [aquatic insects] and cover for fry and fingerlings," said Grummer. "Survey sites harboring substantial plant beds are the locations where we surveyed the greatest numbers of young of the year yellow perch, bluegills, and largemouth bass. At areas containing no plant life, we encountered no perch, bluegill, or largemouth bass fingerlings.

"There's no question that it was a very successful production year at Clear Lake," says Grummer. "Future year classes of sportfish will receive a huge benefit from this year's hatch."